AC Power
AC Power refers to electrical energy that reverses direction in a repeating cycle allowing efficient long distance transmission
AC Voltage
AC Voltage changes polarity in a sinusoidal pattern enabling efficient power distribution
Accuracy
Accuracy describes how near a measurement or reading is to the actual value ensuring reliable operation
Acoustic Noise
Acoustic Noise refers to audible disturbances produced by equipment or environments that may affect communication clarity
Active Component
An Active Component uses external energy to control or amplify signals such as transistors and integrated circuits
Active Filter
An Active Filter shapes frequency response using amplifiers and powered elements for precise signal control
Active Mode
Active Mode describes when a device is fully powered and performing its intended function
Adapter
An Adapter converts physical or electrical interfaces allowing different devices to connect and operate together
Address Bus
The Address Bus transports location information from processor to memory enabling data access
Adhesion
Adhesion describes how strongly two surfaces stick together affecting material durability and assembly quality
Admittance
Admittance is the inverse of impedance showing how readily a circuit allows alternating current
Aerial
An Aerial is a structure designed to transmit or receive electromagnetic waves for communication
AF Signal
An AF Signal carries sound information within the human hearing range for communication and processing
Afterglow
Afterglow is the continued emission of light after excitation stops often seen in phosphor materials
AGC
AGC adjusts signal levels automatically to maintain consistent output preventing overload or distortion
Aging Drift
Aging Drift refers to gradual variation in component characteristics due to long term use and environmental exposure
Air Core Coil
An Air Core Coil uses only air as its core providing stable inductance at high frequencies
Air Gap
An Air Gap controls magnetic flux and inductance in transformers and motors
Alias Frequency
Alias Frequency occurs when signals are sampled too slowly causing incorrect frequency representation
Alignment
Alignment ensures components or systems are positioned correctly for maximum efficiency and accuracy
Alkaline Battery
An Alkaline Battery uses alkaline electrolyte to deliver stable voltage for portable devices
All Pass Filter
An All Pass Filter maintains amplitude while altering phase for signal correction and timing control
Alpha Particle
An Alpha Particle is a positively charged particle emitted during radioactive decay with limited penetration
Alternator
An Alternator converts mechanical energy into alternating electrical energy for power systems
Altitude
Altitude measures vertical distance from sea level affecting radio propagation and atmospheric behavior
Ambient Noise
Ambient Noise refers to environmental sound that may interfere with communication clarity
Amplification
Amplification boosts the magnitude of electrical signals for processing and transmission
Amplifier
An Amplifier raises signal amplitude without altering its basic form enabling stronger output
Amplitude
Amplitude represents the maximum value of a signal indicating its strength or intensity
Amplitude Modulation
Amplitude Modulation varies carrier amplitude to encode information for radio transmission
Analog Signal
An Analog Signal changes smoothly over time representing real world information such as sound or temperature
Analyzer
An Analyzer measures and displays characteristics of electrical or radio signals for diagnostics
Antenna
An Antenna converts electrical signals into electromagnetic waves and vice versa for communication
Antenna Gain
Antenna Gain describes how well an antenna focuses energy in a specific direction improving performance
Antenna Pattern
An Antenna Pattern shows how an antenna radiates energy in space affecting coverage and range
Anti Static
Anti Static methods reduce buildup of electrical charge preventing damage to sensitive components
Aperture
An Aperture defines the effective area through which electromagnetic energy enters or exits a system
API
An API defines rules for software components to communicate enabling integration and automation
Apparent Power
Apparent Power represents total power in an AC system including usable and stored energy
Arc Flash
Arc Flash is a dangerous release of energy from a fault causing heat and light hazards
Array
An Array stores multiple values in a structured sequence for efficient access and processing
Artifact
An Artifact is an unintended alteration in audio video or data caused by processing limitations
Asynchronous
Asynchronous events operate independently without shared timing signals enabling flexible communication
Attenuation
Attenuation describes loss of power as a signal travels through a medium or system
Attenuator
An Attenuator lowers signal amplitude without distorting waveform for testing and protection
Audio Frequency
Audio Frequency spans from low to high tones used in communication and sound reproduction
Auto Transformer
An Auto Transformer uses one winding to step voltage up or down with high efficiency
Auxiliary Power
Auxiliary Power provides backup or supplemental energy for systems requiring reliability
Backscatter
Enables long‑distance HF propagation
Backstay Antenna
Uses sailboat rigging as radiating element
Balanced Line
Low‑loss feedline resistant to noise
Band Edge
Operators must avoid transmitting beyond it
Band Plan
Defines mode segments within amateur bands
Band Scope
Shows signals across a frequency span
Bandpass Filter
Removes unwanted frequencies above and below a target band
Bandwidth
Determines data rate and signal capacity
Base Loading
Electrically lengthens short antennas
Baseband
Lowest frequency form before modulation
Battery Eliminator
powered DC supply
Battery Pack
Provides DC power for handheld radios
Beacon
Sends identification or propagation data
Beacon Mode
Used for testing propagation paths
Beam Antenna
Focuses RF energy in a specific direction
Beamwidth
Defines directional coverage of antennas
Beat Note
Used in CW reception and tuning
Bench Supply
Used for testing and powering equipment
BFO
Creates audible tones for CW/SSB reception
Bias Tee
Combines RF and DC on one feedline
Biconical Antenna
like antenna
Binary Counter
Used in timing and frequency division
Bird Watt Dummy Load
Allows safe RF testing with power measurement
Bird Wattmeter
Industry
Bit Error Rate
Measures digital signal quality
Bitrate
Determines speed of digital modes
Bleed
Adjacent channel interference
Bleeder Resistor
Ensures safety by draining stored energy
Blocking
Strong signals reduce sensitivity to weak ones
Blocking Filter
Protects receivers from strong out‑of‑band signals
BNC Connector
Quick‑lock connector for test gear and radios
Bonded Ground
Reduces RF noise and improves safety
Bonding
Reduces noise and improves grounding
Boot Time
Time required for firmware and DSP to initialize
Bootloader
Allows updating radio firmware safely
BPSK
Digital mode shifting phase between two states
Braid Shield
Reduces RF leakage and interference pickup
Break
Automatic CW keying
Breakout Box
Allows probing of individual wires in a harness
Bridge Circuit
Used for impedance and SWR testing
Bridge Rectifier
Uses four diodes to produce full‑wave DC
Broadband Antenna
Operates across large frequency ranges
Broadcast Interference
Strong broadcast signals overload receivers
Broadside Array
Produces strong perpendicular radiation
Buffer Amplifier
Prevents loading and stabilizes oscillators
Bus Bar
Provides low‑impedance ground distribution
Bypass Capacitor
Removes RF noise from power lines
Byte
Standard data block in computing and digital modes
Capacitance
Measured in farads and used in filters and tuning
Capacitor
Used in filtering
Capture Effect
Stronger FM signal suppresses weaker one
Carbon Microphone
Uses carbon granules to vary resistance with sound
Cardioid Pattern
Rejects sound from rear and sides
Carrier Squelch
Opens audio when RF exceeds threshold
Cathode
Emits electrons in vacuum tubes
Cathode Follower
Provides low output impedance
Cavity Filter
Used in repeaters for isolation and selectivity
Center Conductor
Carries RF signal inside coaxial cable
Center Loading
Electrically lengthens short antennas
Ceramic Filter
Provides selectivity in receivers
Chassis Ground
Connects metal chassis to earth ground
Chirp
Caused by poor oscillator regulation
Choke
Prevents RF from flowing on unwanted paths
Coax Switch
Routes radios to different antennas
Coaxial Cable
Transmits RF with low loss and shielding
Codec
Converts analog audio to digital and back
Collinear Antenna
Provides high gain in vertical pattern
Combiner
Merges signals from multiple transmitters
Common Mode
Often unwanted RF on coax shield
Common Mode Choke
Removes RF from coax shield
Communications Receiver
Designed for HF/VHF monitoring
Compander
Improves audio dynamic range
Compression
Reduces loud peaks for consistent audio
Condenser Microphone
Sensitive mic requiring power
Conductor
Copper or aluminum used in wiring and antennas
Connector
Joins cables and equipment
Control Operator
Ensures legal and proper operation
Counterpoise
Provides RF return path for vertical antennas
Coupling Capacitor
Blocks DC while passing signals
Crest Factor
Important in digital and SSB signals
Crystal
Provides stable oscillation in radios
Crystal Filter
Provides sharp selectivity in IF stages
CTCSS
Used for repeater access and squelch control
Current
Measured in amperes
Current Limiter
Prevents excessive current draw
Cutoff Frequency
Frequency where attenuation begins
CW
Morse code transmission using on/off keying
Cycle
Basis of frequency measurement
Cycling
Turning equipment on/off to reset or test
Cylindrical Antenna
Used in VHF/UHF omnidirectional systems
D
Digital amateur radio mode
Damping
Controls overshoot in circuits and antennas
Damping Resistor
Stabilizes circuits and prevents ringing
Data Burst
Used for IDs
Data Mode
Includes FT8
dBd
Measures antenna gain vs a half‑wave dipole
dBi
Measures antenna gain vs theoretical point source
dBm
Standard RF power measurement unit
dBµV
Used in cable and broadcast measurements
DC Ground
Provides safety and reference potential
DC Offset
Causes distortion in audio and digital signals
De
High‑frequency reduction
De
Receiver sensitivity loss
Decibel
Used for gain
Decoder
Converts encoded or digital signals to usable form
Delta Loop
Triangular loop with low noise and good gain
Demodulator
Converts modulated signals back to baseband
Detector
Converts RF to audio or DC
Deviation
Determines loudness and bandwidth of FM signals
Diaphragm
Converts sound waves into electrical signals
Dielectric
Used in capacitors and coax cable
Dielectric Loss
Causes heating and reduced efficiency
Differential Mode
Desired mode for balanced lines
Digital Filter
Provides precise shaping of signals
Digital Noise
Caused by switching supplies and processors
Diplexer
Allows two antennas or radios on one feedline
Dipole
Most common and fundamental antenna type
Directional Antenna
Improves signal strength and reduces noise
Directional Coupler
Measures forward and reflected power
Discone
Covers large frequency ranges with low SWR
Distortion
Caused by overload or nonlinearity
Diversity Reception
Reduces fading by combining signals
Doppler Shift
Affects satellites and moving sources
Double Conversion
Improves selectivity and image rejection
Doublet Antenna
Used with tuners for wide HF coverage
Downconverter
Converts microwave signals to HF/VHF
Drain
Controls current flow in field‑effect transistors
Driver Stage
Boosts signal before final amplifier
Dropout
Common in digital modes and weak FM reception
Dummy Load
Allows full‑power testing without radiating
Duplex
Used in repeaters and full‑duplex systems
Duplexer
Separates TX and RX paths on one antenna
Duty Cycle
Important for amplifier and mode safety
Dwell Time
Used in scanning and hopping systems
Dynamic Microphone
Rugged mic using magnetic induction
Dynamic Range
Key receiver performance metric
E Field
Electric field component
E Layer
Ionospheric layer
Earth Loop
Causes hum and noise due to multiple ground paths
Echolink
linked repeater system
Eddy Currents
Cause heating and losses in conductors and metal structures
Effective Radiated Power
Power radiated considering antenna gain and losses
Efficiency
Indicates how effectively an antenna or amplifier performs
EIRP
Power radiated relative to isotropic radiator
Electret Microphone
Common in radios for clear audio with low power use
Electrolytic Capacitor
Used in power supplies and audio circuits
Electromagnetic Field
Fundamental to radio wave propagation
Electromagnetic Interference
Unwanted RF energy disrupting circuits and receivers
Electromotive Force
Drives current through a circuit
Electron Tube
Used in amplifiers
Electroplating
Used for connectors and conductive surfaces
Electrostatic Discharge
Can damage sensitive components and radios
Element
Conductive structure that emits or receives RF energy
Elevation Angle
Determines long‑distance HF propagation effectiveness
Elliptical Filter
Provides steep skirts with low ripple
EME
Uses moon as passive reflector for VHF/UHF signals
EMF Exposure
Limits operator exposure to electromagnetic fields
Emitter
Controls current flow in bipolar transistors
End
Single‑wire antenna
End
Wave
End
Directional antenna array
Engine Generator
Provides emergency power for radio stations
Envelope Detector
Extracts audio from amplitude‑modulated signals
Envelope Power
Power measured at modulation peaks
Environmental Noise
Caused by power lines
EPC Mode
Popular contesting mode in PSK clubs
EPROM
Stores firmware in older radios
Equalization
Adjusts tone for clarity and intelligibility
Equinox Propagation
HF conditions improve around equinoxes
ERP
Power radiated after antenna gain and losses
Error Correction
Adds redundancy to recover corrupted bits
Error Vector Magnitude
Indicates modulation accuracy in digital modes
Escape Radiation
Unintended RF leaving equipment or shielding
Ethernet
RF Bridge
Eutectic Solder
Produces strong joints with minimal cracking
Exciter
Drives the final amplifier in transmitters
Exhaustive Scan
Receiver scans entire frequency range for activity
External Speaker
Improves clarity and volume of radio audio
External Tuner
Matches antenna impedance to transmitter
Eye Pattern
Shows signal quality and timing in digital modes
Eyelet Terminal
Used in grounding and power connections
EZNEC
Simulates antenna patterns and performance
F-Connector
Threaded RF connector
Fading
Caused by multipath or ionospheric changes affecting received signal strength
Faraday Cage
Blocks external electromagnetic fields using conductive material
Faraday Rotation
Occurs when HF signals pass through the ionosphere
Feedline
Includes coax
Feedpoint
Determines impedance and radiation characteristics
Ferrite Bead
Reduces high‑frequency noise on cables and circuits
Ferrite Choke
Prevents common‑mode RF on coax and power lines
Ferrite Rod Antenna
Used in AM broadcast receivers
FET
Voltage‑controlled semiconductor used in RF stages
Field Day
Annual amateur radio operating exercise simulating emergency conditions
Field Strength Meter
Measures strength of nearby RF fields
Filter
Passes desired frequencies while rejecting others
Filter Capacitor
Smooths rectified DC to reduce ripple
Final Amplifier
Boosts signal to full transmit power
Firmware
Controls radio functions and digital processing
First IF
Used in superheterodyne receivers for selectivity
Fishbone Antenna
Provides directional gain using staggered elements
Fixed Station
Operates from a fixed location with stable power and antennas
Flameproof Resistor
Designed not to ignite under overload
Flash Memory
Stores settings and firmware in radios
Flat Audio
No emphasis or compression applied
Flex Radio
High‑performance software‑defined radios
Floating Ground
Can cause noise or instability in circuits
Flutter
Caused by multipath or auroral propagation
FM Deviation
Determines loudness and bandwidth of FM signals
FM Squelch
Opens audio when FM signal exceeds threshold
Folded Dipole
Provides broader bandwidth and higher impedance
Footswitch
Allows operators to transmit without using hands
Forward Power
Power flowing toward the antenna
Fox Hunt
Direction‑finding activity for training and fun
Fractional
Frequency synthesizer type
Frame Error
Occurs when packet framing is corrupted
Free Space Loss
Predictable loss in unobstructed line‑of‑sight paths
Frequency
Measured in hertz and defines radio channels
Frequency Counter
Measures oscillator and signal frequencies
Frequency Drift
Caused by temperature or component instability
Frequency Hopping
Used in spread‑spectrum and secure communications
Frequency Modulation
Encodes information by varying frequency
Frequency Multiplier
Produces higher frequencies from a lower one
Frequency Response
Determines clarity and tonal balance
Frequency Stability
Important for digital modes and narrowband signals
Front End
Determines sensitivity and overload resistance
Front Panel Lock
Prevents accidental button presses
Frost Line Grounding
Places rods below frost line for stability
Fused Power Cable
Includes inline fuse to prevent overload damage
Fusible Resistor
Opens under overload to protect circuits
FWD/REF Meter
Measures SWR and antenna match quality
Gain
Expresses how much an antenna or amplifier boosts a signal
Gain Compression
Output stops increasing linearly at high input levels
Galvanic Isolation
Prevents direct current flow between circuits for safety and noise reduction
Gamma Match
Matches impedance of Yagi and other antennas to feedline
Gate
Controls current flow in field‑effect transistors
Gate Leakage
Indicates breakdown or aging in semiconductors
Gaussian Noise
Common in RF systems and thermal environments
Geometric Attenuation
RF power decreases with square of distance
Geometric Mean
Used in RF calculations involving impedance and filters
Geostationary Satellite
Appears stationary relative to Earth for continuous coverage
Geosynchronous Orbit
Satellite remains above same longitude for stable communication
GFI Outlet
Protects against shock by detecting leakage currents
Ghosting
Caused by delayed reflections in analog TV signals
GHz
Represents billions of cycles per second
Gigabit Ethernet
Used for SDRs and remote radio control
Gimbal
Keeps antennas or cameras level during movement
Glide Slope Interference
Caused by nearby transmitters affecting landing systems
Global Noise Floor
Influenced by storms
Glow Discharge
Used in voltage regulators and neon indicators
GMDSS
Global distress and safety communication system for ships
GMRS
UHF personal radio service requiring FCC license
GND
Common return path for electrical circuits
GOTA Station
Field Day station for new operators
GPIB
Used to control test equipment in labs
GPSDO
Provides extremely stable frequency reference using GPS timing
Gradient Antenna
Designed for specific directional coverage
Gradient Noise
Caused by environmental or atmospheric changes
Grain Boundary
Affects conductivity and RF performance in metals
Grid Current
Indicates operating condition of vacuum tubes
Grid Dip Meter
Detects resonant frequency of circuits and antennas
Grid Leak Resistor
Provides bias and stability in vacuum tube circuits
Grid Modulation
Applies audio to control grid for AM transmission
Ground Bonding
Ensures equal potential and reduces RF noise
Ground Bus
Provides unified low‑impedance grounding point
Ground Fault
Causes current leakage and safety hazards
Ground Lift
Reduces hum in audio systems when used safely
Ground Loop Isolator
Eliminates hum caused by multiple ground paths
Ground Plane
Required for vertical antennas to radiate efficiently
Ground Radials
Improve efficiency of vertical antennas
Ground Rod
Provides low‑resistance path to earth
Ground Wave
Used by AM broadcast and low‑frequency systems
Group Delay
Important in filters and digital systems
Group Delay Distortion
Affects digital modes and wideband signals
Guard Band
Prevents interference between adjacent channels
GUI
Visual interface for controlling radios and software
Gunn Diode
Used in radar
Gunnplexer
Simple microwave transceiver for amateur microwave bands
Guy Wire
Stabilizes towers and masts
Gyro Stabilizer
Keeps antennas aligned on moving platforms
Half
Basic resonant antenna
Half Duplex
at
Hand Capacity Effect
Affects tuning of portable radios
Harmonic
Unwanted multiples of a fundamental signal
Harmonic Distortion
Caused by nonlinear amplification
Harmonic Filter
Removes harmonic energy from transmitters
Harmonic Trap
Removes specific unwanted harmonic frequencies
Hartley Oscillator
Uses tapped inductor for stable RF generation
Hash Noise
Caused by switching supplies and digital electronics
Headset
Provides hands‑free operation for radio use
Hearing Assist Loop
Provides audio to hearing aids via magnetic coupling
Heat Dissipation
Critical for amplifiers and power supplies
Heat Sink
Removes heat from transistors and amplifiers
Helical Antenna
Provides circular polarization for satellites
Helical Coil
Used in filters and matching networks
Helical Resonator
Used in VHF/UHF receivers for selectivity
Heliograph Interference
Caused by reflective surfaces producing RF noise
Heterodyne
Produces sum and difference frequencies
Heterodyne Oscillator
Generates frequency for superheterodyne conversion
HF
3–30 MHz band used for long‑distance communication
HF Noise Floor
Influenced by storms
HF Propagation
Influenced by solar activity and ionosphere
HF Vertical
Uses ground radials for efficient low‑angle radiation
High
Filter passing high frequencies
High
AM modulation method
High
Narrowband resonant circuit
High Impedance
Used in audio and RF circuits
High Side Injection
Used in superheterodyne receivers
High SWR
Indicates reflected power and inefficiency
High Voltage
Requires safety precautions in power supplies
Hilbert Transform
Used in SSB generation and demodulation
Hiss
Common in FM receivers with weak signals
Holding Tone
Used for testing audio paths
Hollow
Vacuum tube device
Homebrew
Radios or antennas built by amateurs
Homing Beacon
Used for search
Horizon Distance
Maximum VHF/UHF distance before Earth curvature blocks signal
Horizontal Antenna
Used for HF and weak‑signal VHF work
Horn Antenna
Used for microwave links and measurements
Hot Carrier Diode
Used in mixers and RF detectors
Hot Spot
Provides wireless network connectivity
HT
Portable VHF/UHF radio
Hum
Caused by grounding issues or AC leakage
Hybrid Coupler
Provides phase‑shifted outputs for antennas
Hybrid Ring
Provides phase‑shifted outputs for microwave circuits
Hydrogen Line
Used in radio astronomy for galactic mapping
Hyperbolic Navigation
Uses timing differences between stations
Hz
Cycles per second
Iambic Keying
Allows alternating dits and dahs using squeeze technique
Iambic Paddle
Enables efficient Morse code sending
IC
Miniaturized electronic circuit in a single package
Ice Loading
Affects antennas and towers during winter
IF
Fixed frequency used in superheterodyne receivers for filtering
IF Filter
Determines bandwidth and adjacent‑channel rejection
IF Shift
Moves IF filter passband to reduce interference
IF Tap
Allows connection to panadapters and SDRs
Image Frequency
Produces interference if not filtered properly
Image Rejection
Prevents unwanted image frequencies
Impedance
Measured in ohms and critical for matching systems
Impedance Analyzer
Measures complex impedance across frequencies
Impedance Bridge
Determines unknown impedance values
Impedance Matching
Maximizes power transfer and reduces SWR
Impulse Noise
Caused by motors
Inband Signaling
Sends tones or data inside the main RF channel
Incoherent Scatter
Used in scientific radar studies
Incremental Tuning
Allows precise tuning in small steps
Inductance
Property of coils resisting changes in current
Inductive Coupling
Transfers energy between coils without contact
Inductive Reactance
Increases with frequency
Inductor
Used in filters
Infrared Link
Used for remote controls and some data systems
Ingress Noise
Noise entering coax from poor shielding
Input Impedance
Determines matching requirements for sources
Inrush Current
Occurs when powering equipment with large capacitors
Insulator
Prevents current flow and supports antennas
Interdigital Filter
Uses parallel resonators for sharp selectivity
Interference
Caused by noise
Intermediate Power Amplifier
Boosts signal before final amplifier
Intermodulation
Produces unwanted spurious frequencies
Internal Speaker
Provides basic audio output in radios
Interstage Coupling
Uses capacitors or transformers to pass signals
Inversion Layer
Enhances VHF/UHF propagation over long distances
Inverted
Bent wire antenna
Inverted
Sloped dipole antenna
Ionization
Creates charged particles essential for HF propagation
Ionosonde
Measures ionospheric layers and propagation conditions
Ionospheric Absorption
Caused by solar events and D‑layer activity
Ionospheric Delay
Affects GPS and HF timing accuracy
Ionospheric Disturbance
Causes blackouts and degraded HF conditions
Ionospheric Reflection
Enables long‑distance communication via skywave
IP Rating
Indicates dust and water resistance of equipment
IP3
Key measure of receiver linearity and overload resistance
Isolation Transformer
Provides galvanic isolation for AC lines
Isotropic Radiator
Radiates equally in all directions
ITU
Governs global radio regulations and allocations
IV Curve
Used to analyze semiconductor behavior
J-Pole Antenna
End
J-Pole Match
Matching section of J
Jack
Provides interface for audio
Jamming
Deliberate RF disruption to block communication
Jansky
Measures radio source strength in scientific observations
Java Radio Control
based radio control
Jitter
Causes distortion in digital signals and clocks
Joule
Represents work done by one watt for one second
Joule Heating
Occurs when current flows through resistive materials
Joule Thief
Uses a coil and transistor to raise voltage from low sources
JTAG
Used for programming and testing digital circuits
Jumper Adapter
Converts one connector type to another
Jumper Assembly
made jumper set
Jumper Block
Used to set hardware options on circuit boards
Jumper Bus
connection bus
Jumper Cable
Used to link components or test points
Jumper Clip
on test connector
Jumper Control
Sets hardware modes or options
Jumper Fuse
Provides protection while acting as a link
Jumper Harness
wire jumper assembly
Jumper Header
pin connector
Jumper Interface
Allows manual configuration of circuits
Jumper Kit
Contains various lengths and types for prototyping
Jumper Lead
Used for temporary electrical connections
Jumper Link
Used to connect two points permanently
Jumper Lug
Used for grounding or power distribution
Jumper Mapping
Shows configuration options and effects
Jumper Matrix
Allows multiple configuration combinations
Jumper Module
Provides configurable circuit options
Jumper Pad
Used to bridge or cut for configuration changes
Jumper Pin
Used on PCBs for configuration
Jumper Plug
Used to open or close circuits on equipment
Jumper Post
Used on PCBs for configuration
Jumper Rail
Provides distribution point on breadboards
Jumper Routing
Determines layout and signal integrity
Jumper Selector
Provides easy switching between modes
Jumper Settings
Set by placing jumpers on pins
Jumper Socket
Used for modular wiring and testing
Jumper Switch
Allows configuration without removing hardware
Jumper Terminal
Provides removable wiring connection
Jumper Trace
Cuttable trace for hardware configuration
Jumper Wire
Used on breadboards and prototyping boards
Junction Box
Protects wiring connections and splices
Junction Diode
Allows current in one direction and blocks the other
Junction Temperature
Critical for reliability and performance
Junction Transistor
Uses emitter
Junk Box
Storage of miscellaneous components for projects
Jupiter Noise
Strong radio noise from Jupiter detectable on HF
K
Temperature sensor type
K
Microwave frequency band
K
Geomagnetic storm warning
K Factor
Used to adjust antenna measurements for accurate field strength readings
K Index
Measures short‑term geomagnetic activity affecting HF propagation
Key Bounce
Causes multiple unintended keying events
Key Clicks
Caused by abrupt keying transitions in CW transmitters
Key Down
Used for tuning and testing transmitters
Keyer
Automates Morse code timing and sending
Keyer Paddle
Used with electronic keyers for Morse code
Keying Envelope
Determines smoothness and click suppression
Keying Line
Activates transmitter during CW or digital operation
Keypad Entry
Allows direct frequency input on radios
Keystone Jack
Used for Ethernet and structured cabling
KiloCycle
Legacy unit for thousands of cycles per second
KiloHertz
Represents thousands of cycles per second
Kilometric Waves
Used for submarine and long‑range communication
Kilovolt
Equal to 1000 volts
Kilovolt‑Ampere
Used in AC power systems and generators
Kilowatt
Equal to 1000 watts and used for high‑power transmitters
Kilowatt Hour
Measures energy usage over time
Kinetic Energy Loss
Occurs in resistive and mechanical systems
Kinetic Inductance
Occurs in superconductors and high‑frequency circuits
Kinetic Noise
Caused by mechanical vibration affecting components
Klystron
Used in radar and high‑power microwave systems
Klystron Oscillator
Generates stable microwave frequencies
Knee Current
Current at which diode begins significant conduction
Knee Frequency
Frequency where attenuation begins
Knee Point
Voltage where core begins to saturate
Knee Point Analysis
Determines saturation characteristics
Knee Point Current
Current where magnetic core begins to saturate
Knee Point Curve
Shows relationship between voltage and flux density
Knee Point Detection
Used in transformer and inductor testing
Knee Point Limit
Ensures components avoid saturation
Knee Point Region
Area where device behavior changes rapidly
Knee Point Shift
Caused by temperature or aging
Knee Point Stability
Important for precision magnetic components
Knee Point Voltage
Used in current transformer specifications
Knee Resistance
Occurs in semiconductors near conduction threshold
Knee Saturation
Occurs when inductors or transformers reach magnetic limits
Knee Voltage
Voltage at which a diode begins to conduct significantly
Knee Voltage Drop
Voltage where diode transitions from off to on
Knife Switch
Used in high‑current or visible switching applications
Knot
Used in marine communications and navigation
Kohm
Represents 1000 ohms of resistance
Kovar
Used in vacuum tubes and hermetic components
Kurtosis
Used in analyzing digital modulation quality
Kurtosis Noise
Affects digital signal quality and decoding
L Band
Covers roughly 1–2 GHz used for GPS and satellite links
L Network
Uses one inductor and one capacitor for simple matching
L/C Meter
Measures values of coils and capacitors
Ladder Line
conductor feedline
Lag
Time difference between input and output in systems
LAN
Connects computers and SDRs within a local environment
Latching Relay
Maintains position without continuous power
Latching Switch
Used for power and mode selection
Lattice Filter
Provides sharp selectivity in RF circuits
Launch Angle
Determines HF skip distance and propagation
LC Circuit
capacitor circuit
Lead Acid Battery
Common in backup power and mobile stations
Leakage Current
Flows through insulation or components
LED Indicator
emitting diode indicator
Leeds Line
Used in early radio experiments
Legacy Mode
Supported for compatibility with older systems
Legal Limit
Defined by FCC for amateur radio transmissions
Lenz’s Law
Opposing currents form when magnetic fields change
LF
30–300 kHz used for navigation and long
LID
Refers to operators with bad operating habits
Limiter
Prevents signals from exceeding a set level
Line Loss
Caused by resistance and dielectric heating
Line of Sight
Required for VHF/UHF and microwave communication
Linear Amplifier
Boosts signal without distortion
Linear Mode
Required for SSB and AM to avoid distortion
Linearity
Determines distortion and IMD performance
Link Coupling
Transfers RF energy between circuits
Link Margin
Ensures reliable communication under fading
Lithium Battery
Used in handheld radios and portable gear
Load
Represents power consumption or impedance
Load Coil
Electrically lengthens short antennas for resonance
Load Impedance
Determines matching and power transfer
Loading
Adjusts antenna electrical length
Local Oscillator
Mixes with incoming signals for conversion
Local QRM
made noise
Log
Multi
Logbook
Tracks QSOs
Long Path
Signal travels opposite direction around Earth
Long Wire Antenna
Works across multiple HF bands with tuner
Loop Antenna
loop antenna
Loss Tangent
Indicates RF heating and inefficiency in materials
Low Band
Includes 160m
Low Noise Amplifier
Boosts weak signals with minimal added noise
Low Pass Filter
Blocks higher frequencies and harmonics
Low SWR
Indicates efficient power transfer to antenna
Low Voltage Dropout
Provides stable voltage with minimal input overhead
LPF
pass filter
LRS
range system
Lumped Element
Represents idealized inductors
Mag Loop
Small
Magnetic Field
One half of electromagnetic radiation
Magnetic Mount
Uses magnet to secure antenna to vehicle roof
Magnetron
Used in radar and microwave ovens
Main Lobe
Strongest part of an antenna’s radiation pattern
Mains Filter
Removes RF noise from power lines
Male Connector
type connector
Manpack Radio
Used for field operations and emergency comms
Manual Gain Control
Allows operator to set receiver sensitivity
Marker Beacon
Provides landing guidance for aircraft
Master Oscillator
Generates stable reference frequency for radios
Matched Load
Ensures minimal reflection and maximum power transfer
Matching Network
Uses L
Matrix Switch
Routes multiple radios to multiple antennas
Maximum Usable Frequency
Highest frequency usable for ionospheric propagation
Mean Power
Represents average transmit power over time
Mechanical Filter
Provides sharp selectivity using vibrating elements
Medium Wave
Covers 530–1700 kHz
Megahertz
Millions of cycles per second
Memory Channel
Saves frequency
Mesh Network
Provides resilient communication paths
Meter Bridge
Measures audio levels in recording and radio systems
Mic Gain
Adjusts audio input level for transmit audio
Mic Preamp
Boosts mic
Microcontroller
Controls radio functions and digital systems
Microphone
Converts sound into electrical signals
Microwave
Frequencies above 1 GHz used for links and radar
Millihenry
One‑thousandth of a henry
Millivolt
One‑thousandth of a volt
Mini
RF component manufacturer
Minimum Discernible Signal
Weakest signal a receiver can detect
Mismatch Loss
Reduces power transfer efficiency
Mixer
Combines signals to produce sum and difference frequencies
Mobile Antenna
mounted antenna
Mode J
Uses 2m uplink and 70cm downlink
Mode L
Uses 23cm uplink and 70cm downlink
Mode S
Provides aircraft ID and altitude data
Modem
demodulator
Modulation
Includes AM
Modulation Index
Determines loudness and bandwidth of AM/FM signals
Modulator
Applies audio or data to RF carrier
Monitor Receiver
Used to monitor transmissions or control channels
Monoband Antenna
Optimized for one frequency band
Monopole
Requires ground plane or radials
MOSFET
Used in RF amplifiers and switching circuits
Mounting Bracket
Secures radios
Multiband Antenna
Operates on several HF/VHF bands
Multimeter
Measures voltage
N Type Semiconductor
Electron
N-Connector
Threaded RF connector
N-FET
Type of field
Narrow FM
Used in commercial and amateur VHF/UHF channels
Narrowband
Used for FM
Narrowband Filter
selectivity filter
National Traffic System
Handles formal traffic across amateur radio operators
Natural Noise
Includes lightning
Near Vertical Incidence Skywave
Provides short
Negative Feedback
Reduces distortion and improves linearity
Negative Peak Limiter
Prevents overmodulation on negative peaks
Negative Resistance
Seen in tunnel diodes and oscillators
Neon Lamp
discharge indicator
Network Analyzer
Measures impedance
Network Keyer
Shares keying between multiple radios
Network Node
Used in mesh networks and VoIP systems
Network Repeater
Connects repeaters via internet or RF links
Neutralization
Cancels unwanted feedback in amplifiers
Noise
Interferes with reception and reduces intelligibility
Noise Blanker
Removes sharp noise pulses in receivers
Noise Bridge
Determines unknown impedance using noise source
Noise Figure
Lower values indicate better sensitivity
Noise Floor
Determines minimum detectable signal
Noise Gate
Mutes audio below a set level
Noise Limiter
Reduces impulse noise in AM receivers
Noise Reduction
Improves clarity by removing background noise
Noise Source
Used for testing filters and amplifiers
Noise Suppressor
Reduces interference from power lines and electronics
Nominal Impedance
Common values include 50Ω and 75Ω
Non
Capacitor without polarity
Non Coherent Detection
Detection without phase reference
Non Directional Beacon
NDB aviation beacon
Non Inverting Amplifier
Amplifier configuration
Non Linear Device
Device with nonlinear response
Notch Antenna
rejecting antenna
Notch Filter
Removes a narrow unwanted frequency
Notch Tuner
Cancels specific resonances or interference
Notching
Used to eliminate interference or carriers
NRSC
Defines AM/FM broadcast technical standards
Null
Used for direction finding and noise rejection
Null Fill
Adds signal strength in antenna null regions
Null Modem
Connects two devices directly without modem
Number Station
Transmits coded messages for intelligence operations
Numerical Aperture
Determines light acceptance angle
Numerical Control
controlled machining
Nyquist Frequency
Maximum frequency that can be sampled without aliasing
Nyquist Rate
Twice the highest signal frequency for accurate reproduction
O-Scope
Oscilloscope
OAT
Environmental factor affecting RF propagation and equipment
Oblong Loop
Provides directional gain and low noise
Obstruction Loss
Caused by buildings
Octave
Represents a 2:1 frequency ratio
Offset
Used in repeaters for separate transmit and receive frequencies
Offset Dipole
Provides multiband performance with tuner
Ohm
Measures opposition to current flow
Ohmic Loss
Converts RF energy into heat
Ohmmeter
Measures resistance in circuits and components
Omnidirectional Antenna
degree coverage antenna
On Air
Actively transmitting or receiving
Open Circuit
Prevents current flow in a circuit
Open Feedline
Includes ladder line and open
Open Stub
Used for impedance matching and filtering
Operating Position
Includes radio
Operating System
Runs radio control and digital mode applications
Operational Amplifier
amp device
Operational Mode
Includes AM
Optical Fiber
based transmission medium
Optimum Working Frequency
Best frequency for reliable HF communication
Opto
Isolated push
Optocoupler
isolated switch
Orthogonal Frequency Division Multiplexing
Uses multiple subcarriers for robust data transmission
Orthogonal Polarization
Used to reduce interference between signals
Oscillation
Fundamental to RF generation and timing circuits
Oscillator
generating circuit
Oscillator Drift
Caused by temperature or component aging
Oscillator Pulling
Occurs when oscillator interacts with circuits
Oscillator Startup Time
Important for digital and RF systems
Oscilloscope Probe
Connects circuits to oscilloscopes safely
Output Coupler
Couples RF energy to feedline or test equipment
Output Filter
Removes unwanted frequencies from transmitter output
Output Impedance
Important for matching and power transfer
Output Power
Measured in watts and determines signal strength
Overcurrent
Can damage components or wiring
Overload
Causes distortion or receiver desensitization
Overmodulation
Causes distortion and splatter in AM/FM
Overvoltage
Can damage circuits and components
Owen’s Bridge
Measures inductance and resistance
Oxidation
Increases resistance and degrades connectors
Oxygen
High
Ozone Layer Absorption
Affects some microwave frequencies
Ozone Noise
Caused by electrical storms and ozone activity
P-Channel FET
P
P-Mode
Propagation mode classification
Packet Radio
Sends data in structured packets over RF links
Pad Attenuator
value attenuator
Parabolic Antenna
shaped antenna
Parallel Circuit
voltage circuit
Parametric Amplifier
noise RF amplifier
Passband
Frequencies passed by a filter or communication channel
Passive Component
powered component
Patch Antenna
Used in GPS
Patch Panel
Routes and organizes network or RF cables
Peak
Peak Voltage
Peak Envelope Power
Maximum power during SSB modulation peaks
Peak Hold
Displays highest measured signal level
PEP
Standard measurement for SSB transmitters
Perigee
Satellite’s closest approach to Earth
Periodic Signal
Used in oscillators and modulation systems
Permittivity
Determines how materials store electric fields
Phase
Describes position within a waveform cycle
Phase
PLL frequency system
Phase Angle
Used in AC power and RF calculations
Phase Distortion
Causes audio and RF signal degradation
Phase Noise
Causes jitter and weak
Phase Shift Keying
Encodes data by shifting signal phase
Phasing Method
Uses phase cancellation to create single sideband
Phone Patch
to
Phonetic Alphabet
Ensures clarity of letters during voice communication
Photodiode
sensitive diode
Phototransistor
controlled transistor
Pi Network
Uses two capacitors and one inductor
Pilot Tone
Used for synchronization or squelch systems
PIN Diode
Used in attenuators
Pioneer Band
Historical term for early HF allocations
Pip Tone
Used for timing or identification signals
Pitch Control
Alters oscillator frequency in radios
Pixel Noise
Appears in digital displays or SDR waterfalls
PL Tone
Subaudible tone for repeater access (CTCSS)
PLL Synthesizer
Generates stable frequencies using PLL circuits
Plug
Replaceable circuit module
Polar Diagram
Shows directional gain and nulls
Polarization
Can be vertical
Pole
Determines roll
Polyphase Filter
Used in SDRs for channelization
PON
Fiber system using passive splitters
Preamplifier
level signal amplifier
Preselector
Improves receiver selectivity and reduces overload
Preset
Saves radio settings for quick recall
Propagation
Describes how radio waves move through space
Pulse Modulation
Includes PWM
Pulse Repetition Frequency
Determines radar and digital timing intervals
Q Circuit
Tuned resonant circuit
Q Code
Three‑letter codes used to simplify communication
Q Factor
Indicates sharpness of resonance in filters and tuned circuits
Q Signal
Used to convey common questions and statements quickly
QAM
Digital mode combining amplitude and phase changes for high data rates
QAR
Mechanism for rapidly detaching antennas in field operations
QAV
Describes low‑noise audio output in receivers
QBE
Fast method for switching bands on modern radios
QDC
Allows fast attachment and removal of cables
QEC
DSP technique for improving digital modulation accuracy
QFN Package
Compact IC package used in RF components
QFP Package
Surface‑mount IC package with leads on all sides
QPSK
Digital mode using four phase states for efficient data transfer
QR Code
readable code
QRH
Indicates slow frequency variation during operation
QRL
CW code asking if frequency is in use
QRM
made interference
QRN
Caused by lightning and atmospheric conditions
QRO
Indicates use of high transmitter power
QRP
Indicates use of low transmitter power (typically 5W or less)
QRQ
speed CW
QRS
speed CW
QRT
CW code meaning “shut down” or “stop operation”
QRU
CW code for traffic exchange
QRV
Indicates readiness to operate
QRX
Used to request a pause in communication
QRZ
Used to identify calling stations
QSB
Caused by propagation changes or multipath
QSD
Indicates poor CW waveform quality
QSK
in CW
QSL
Used for confirming QSOs and exchanging cards
QSL Bureau
Handles bulk QSL card distribution
QSO
Exchange of information between two stations
QSP
Indicates forwarding traffic to another station
QSY
Used to request or announce frequency changes
QTC
Indicates formal message content
QTH
Indicates operator’s geographic location
QTR
Used to request or provide the current time
Quad Antenna
Provides gain and directivity similar to a Yagi
Quadrature
Used in modulation and DSP systems
Quadruple Conversion
Provides exceptional image rejection and selectivity
Quagi Antenna
Combines quad loops and Yagi elements for gain and bandwidth
Quality Audio
undistorted audio
Quarter
λ/4 resonant antenna
Quarter
Transmission line stub
Quench Oscillator
Controls oscillation bursts for detection
Quiescent Current
Baseline current in amplifiers and circuits
Quiet Zone
restricted area
R Signal
Received signal report
R Value
Sunspot activity rating
Rack Mount
Holds radios
Radial
Provides RF return path and improves efficiency
Radiation Pattern
Shows how an antenna radiates energy in space
Radiation Resistance
Represents power converted into RF radiation
Radio Frequency
Frequencies used for communication and broadcasting
Radio Horizon
of
Radio Noise
Caused by natural or man
Radio Spectrum
Allocated for communication and services
Radio Teletype
Uses frequency
Radiogram
Used in NTS traffic handling
Rag Chew
Informal extended radio chat between operators
Rake Receiver
combining receiver
Random Wire
resonant wire antenna
Range
Determined by power
Raspberry Pi Radio
based radio controller
Rate of Rise
Important in keying and pulse circuits
Reactance
dependent impedance
Receiver
Converts RF into audio or data
Receiver Desense
Caused by strong nearby transmitters
Receiver Front End
Determines sensitivity and overload performance
Receiver Incremental Tuning
Adjusts receive frequency without changing transmit
Recombination
Affects ionospheric density and HF propagation
Rectifier
to
Redundancy
Ensures reliability in communication systems
Reflected Power
Indicates mismatch and SWR issues
Reflection
Occurs from obstacles or mismatched feedlines
Reflow Soldering
Uses controlled heating to melt solder paste
Regenerative Receiver
Uses positive feedback for gain
Regulated Power Supply
Maintains constant voltage under load
Relay
Used for PTT
Remote Head
Allows flexible mounting in vehicles
Remote Station
controlled station
Repeater
Receives and retransmits signals to extend range
Repeater Offset
Standard spacing for VHF/UHF repeaters
Repeater Tail
of
Resistor
limiting component
Resonance
Occurs when inductive and capacitive reactance cancel
Resonant Antenna
Provides efficient radiation at resonant frequency
Return Loss
Higher values indicate better matching
RF Choke
Prevents RF from entering unwanted paths
RF Gain
Adjusts front
RF Ground
Reduces noise and improves antenna performance
RF Interference
Caused by electronics
RF Power Amplifier
power RF stage
RF Sampler
Extracts small RF portion for measurement
RFI Filter
Reduces RF interference on power or signal lines
RIT
Fine
S Meter
Signal strength meter
S Unit
Standard signal increment
Sallen
Active filter topology
Saltwater Ground
Uses seawater for excellent RF grounding
Sample Rate
Determines maximum representable signal frequency
Sampling Theorem
Defines minimum sampling rate for accurate reproduction
SAQ
Alexanderson alternator transmitter on 17.2 kHz
Satellite Mode
Defines uplink and downlink frequency pairs
Satellite Pass
Time when satellite is visible for communication
Scan Rate
Determines how fast a receiver scans channels
Scanner
channel receiver
Scatter Propagation
Occurs when signals bounce off irregularities
Schottky Diode
switching diode
Scrambler
Alters audio to prevent casual monitoring
Scribble Pad
Used for quick notes during operation
SDR
defined radio
Secondary Emission
Occurs in tubes and CRTs under high energy
Selectivity
Determines how well adjacent signals are rejected
Sensitivity
Key receiver performance metric
Separator Tone
Used in repeater systems for signaling
Series Circuit
path circuit
Series Resonance
Occurs when inductive and capacitive reactance cancel
Service Monitor
Measures modulation
Shadowing
Caused by terrain or buildings blocking signals
Shield
Blocks RF interference and protects circuits
Shielded Cable
protected cable
Short Circuit
Causes excessive current and potential damage
Short Skip
range HF propagation
Shot Noise
Caused by random electron movement
Sideband
Contains audio or data information in AM/SSB
Signal
Noise Ratio
Signal Generator
Produces test signals for alignment and calibration
Signal Path
Describes flow through circuits or systems
Silent Key
Respectful term for operators who have passed
Simplex
frequency operation
Simulcast
transmitter system
Single Conversion
Uses one IF stage for frequency conversion
Single Sideband
Efficient voice mode removing carrier and one sideband
Single Tone
Used for testing and calibration
Sink Current
Important in digital logic and IC design
Skyhook
Informal term for high or improvised antennas
Skywave
Enables long
SWR
Indicates feedline and antenna match quality
SWR Bridge
Measures forward and reflected power to determine SWR
SWR Meter
Shows antenna match and reflected power
Synchronous Detection
Improves audio quality and reduces distortion
Synchronous Oscillator
locked oscillator
Synchronous Receiver
Uses reference oscillator for improved detection
Synchronous Transmitter
aligned transmitter
Synchronous Tuning
Tunes RF and oscillator stages together
T Match
Antenna matching method
T/R Switch
Automatically switches antenna between transmitter and receiver
T2FD Antenna
Broadband HF antenna with low noise characteristics
Tactical Call
Used during events or emergency operations for clarity
Tail
Last station in a net
Tank Circuit
Used in oscillators and amplifiers for frequency control
Tap Point
Used for impedance matching or tuning adjustments
Tapered Line
Used for impedance transformation
Telegraphy
Uses on/off keying for long
Telemetry
Sends sensor data over RF links
Teleprinter
Used historically for RTTY communication
TEM Mode
RF mode with electric and magnetic fields perpendicular to direction
Temperature Coefficient
Indicates how values change with temperature
Terminal Node Controller
Converts data to packet radio signals
Termination
of
Tesla Coil
voltage resonant transformer
Thermal Noise
Present in all electronic components
Thermistor
sensitive resistor
Thermocouple
Generates voltage based on heat difference
Third
IP3 linearity measure
Threshold Squelch
based squelch
Through Loss
Indicates insertion loss of filters or switches
Throw
Defines number of selectable outputs
Thunderstorm Static
Caused by lightning and electrical storms
Tilt Angle
Affects polarization and radiation pattern
Time Constant
Determines charging and discharging speed
Time Division Multiplexing
Shares channel by dividing time slots
Time of Flight
Used in radar and ranging systems
Timebase
Controls sweep rate in oscilloscopes
TNC
Interface for packet radio and APRS
Tone Burst
Used to access certain repeaters
Tone Squelch
Includes CTCSS and DCS systems
Toroid
shaped magnetic core
TOS Meter
Measures SWR and line performance
Touch Keyer
Uses touch
Tower
Provides height for improved coverage
Tracking Generator
Works with spectrum analyzers for filter testing
Transceiver
Performs both transmitting and receiving functions
Transconductance
Ratio of output current to input voltage
Transducer
Converts one form of energy to another
Transfer Switch
Switches between mains and backup power
Transformer
Uses magnetic coupling to change AC levels
Transient
Caused by switching or lightning
Transistor
Fundamental component in modern electronics
Transmatch
Matches transmitter to antenna impedance
Transmission Line
Carries RF from transmitter to antenna
Transponder
Used in satellites and aviation systems
Trap
selective circuit
Tuner
Adjusts antenna system for best SWR
UHF
Covers 300–3000 MHz used for repeaters
UHF Connector
259/SO
UHF Duplexer
Separates TX/RX paths for repeaters
UHF Link
Used for control
UHF Noise Floor
Typically lower than HF but affected by urban noise
UHF Oscillator
frequency oscillator
UHF Preamp
noise UHF amplifier
UHF Propagation
Primarily line
UHF Repeater
Common on 440 MHz amateur band
UHF Spectrum
Used for TV
UHF TV Interference
Occurs when strong UHF signals overload TV receivers
UHF Whip
Common on handheld radios
UHF Yagi
Provides high gain for weak
Ultra
UWB RF technology
Ultralight Receiver
Used for DXing and portable monitoring
Ultrasonic Noise
frequency acoustic noise
Umbrella Antenna
wire vertical antenna
Unattended Beacon
Transmits ID or telemetry without operator present
Unattended Operation
Requires compliance with FCC rules for control
Unbalanced Antenna
Includes verticals and end
Unbalanced Line
ended feedline
Under
Insufficient modulation depth
Underground Feed
Protects coax from weather and damage
Underhung Tower
Used for specific structural designs
Underload
Can cause instability in power supplies
Unidirectional Antenna
direction antenna
Unidirectional Coupler
way RF coupler
Uniform Field
Used in EMC testing and calibration
Uninterruptible Power Supply
Provides temporary power during outages
Unit Step
Used in DSP and control theory
Unity Coupling
Maximum energy transfer between windings
Unity Gain
Output equals input level
Universal Antenna Mount
Fits multiple antenna types and masts
Universal Counter
Measures frequency
Unlicensed Band
use RF band
Unmodulated Carrier
Used for tuning and testing transmitters
Unwanted Emissions
Includes harmonics and intermodulation products
Upconverter
raising device
Uplink
RF path from ground to satellite
Upper Sideband
Used on HF above 10 MHz for voice communication
Upward Refraction
Occurs in certain atmospheric conditions
USB Port
Used for radio control
USB Sound Card
Provides clean audio for digital modes
User Access Tone
Includes CTCSS or DCS for repeater entry
Utility Knife Ground
Simple field
Utility Station
amateur HF station
UV Resistance
Important for outdoor cables and antennas
Variable Attenuator
Controls RF level without distortion
Variable Capacitor
Used in tuning circuits and resonant networks
Variable Inductor
Used for tuning and matching circuits
Variable Resistor
Used for volume
Vector Network Analyzer
Measures impedance
Velocity Factor
Determines electrical length of transmission lines
Ventilation Slot
Prevents overheating in radios and amplifiers
Vertical Antenna
Provides omnidirectional horizontal coverage
Vertical Dipole
Provides low
Vertical Polarization
Common for FM
Vertical Stack
Increases gain by stacking vertical antennas
VFO
Allows continuous tuning of transmit and receive frequency
VFO Drift
Caused by temperature or component aging
VHF
Covers 30–300 MHz used for FM
VHF High Band
Includes 144–148 MHz amateur 2m band
VHF Low Band
Includes 30–50 MHz used for public service and amateur 6m
VHF Propagation
Primarily line
VHF Repeater
Extends communication range on 2m band
Vibrating Reeds
Used in early frequency meters
Vibrating Relay
Used in early radio power supplies
Video Carrier
Main RF component of analog TV transmission
Video Filter
Shapes video signal for clarity and bandwidth control
Video IF
Used in analog TV receivers
Video Noise
Appears as snow or distortion in video signals
Virtual Ground
amps
Viscosity
Relevant for cooling fluids in high
VLF
Covers 3–30 kHz used for navigation and submarine comms
VLF Antenna
Extremely large antennas for long
Voice Coil
Converts electrical signals into sound
Voice Keyer
Sends prerecorded messages during contests
Voice Operated Transmit
Automatically keys transmitter when audio is detected
Voltage
Drives current through circuits
Voltage Divider
resistor network
Voltage Drop
Caused by resistance in wiring or components
Voltage Gain
Ratio of output voltage to input voltage
Voltage Limiter
Prevents excessive voltage from damaging circuits
Voltage Node
Occurs in standing wave patterns
Voltage Regulator
Provides constant voltage despite load changes
Voltage Standing Wave
Indicates mismatch in transmission lines
Voltmeter
Measures AC or DC voltage
Volume Control
Sets loudness in receivers and audio systems
VOR
Aviation navigation system using VHF signals
Vox Delay
Prevents rapid switching between TX and RX
Vox Trip Level
Determines audio level required to trigger transmit
VSWR
Measures feedline mismatch and reflected power
VTVM
High
Water Hammer
Can affect cooling systems in high
Water Ingress
Causes corrosion and detuning in antennas and coax
Waterproofing
Protects outdoor antennas and connectors
Watt
Measures rate of energy transfer in RF and electrical systems
Watt
Energy measurement unit
Watt
Energy unit
Watt Balance
Measures mass using electromagnetic force
Watt Converter
Converts RF power to heat in dummy loads
Watt Density
Used in heating and RF exposure calculations
Watt Efficiency
Ratio of useful output to input power
Wattmeter
Measures forward and reflected power in transmission lines
Wave Absorber
Used in anechoic chambers and shielding
Wave Analyzer
Measures harmonic and spectral content
Wave Attenuator
Reduces amplitude without distortion
Wave Interference
Causes reinforcement or cancellation
Wave Meter
Used historically to measure RF frequency
Wave Propagation
Describes how radio waves move through different media
Wave Trap
Removes unwanted frequencies from power lines
Waveform
Describes amplitude variation over time
Waveform Distortion
Caused by overload or nonlinear circuits
Waveform Generator
Produces sine
Wavefront
Describes propagation direction and timing
Waveguide
Carries microwave signals with low loss
Waveguide Bend
Allows routing of microwave energy
Waveguide Flange
Joins waveguide sections securely
Waveguide Mode
Describes field patterns inside waveguides
Waveguide Short
Creates standing waves for tuning and measurement
Wavelength
Determines antenna size and propagation characteristics
Wavenumber
Number of waves per unit distance
Weak Signal
level RF signal
Weather Fax
Transmits weather charts over HF radio
Whip Antenna
Common on handhelds and mobile radios
White Noise
energy noise
Wideband
Supports high data rates and broad coverage
Wideband FM
deviation FM mode
Wideband Receiver
coverage receiver
Wind Loading
Critical for tower and mast design
Window Line
wire feedline
Wire Antenna
Includes dipoles
Wire Gauge
Determines current capacity and resistance
Wireless Link
Connects devices without physical cables
Work Function
Important in tubes and semiconductor physics
Working Load Limit
Rating for masts
Working Voltage
Rating for capacitors and components
Worm Gear
Used in rotators for precise antenna movement
Wouff
Amateur radio folklore tool
Wraparound Antenna
Mounted around structures for stealth or coverage
WSPR
Low
Wye Connection
phase wiring method
Wye Filter
branch filter network
X Antenna
dipole antenna
X Band
Covers roughly 8–12 GHz used for radar and satellite links
X Capacitor
rated AC capacitor
X Coupler
coupling device
X Frame
shaped antenna frame
X Mode
One of the magneto
X Phase
phase measurement
X Pollination
interference slang
X Port
port interface
X Pulse
polarized pulse
X Reflector
Enhances gain in crossed
X Section
sectional view
X Switch
Routes multiple inputs to multiple outputs digitally
X Terminal
connection terminal
X Tolerance
Indicates acceptable deviation from nominal value
Y
Splitter connector
Y Adapter
Splitter connector
Y Branch
Fiber optic splitter
Y Cable
Split cable assembly
Y Cable
Split cable assembly
Y Coordinate
Vertical axis value
Y Coordinate
Vertical axis value
Y Filter
Admittance
Y Filter
Admittance
Y Load
Split load configuration
Y Load
Split load configuration
Y Match
Antenna matching network
Y Match
Antenna matching network
Y Mode
Polarization mode
Y Mode
Polarization mode
Y Pad
Resistive attenuator pad
Y Pad
Resistive attenuator pad
Y Splitter
Signal splitter
Y Splitter
Signal splitter
Y Tee
Coaxial tee connector
Y Tee
Coaxial tee connector
Y Terminal
Three
Y Terminal
Three
Y Transformer
Three
Y Transformer
Three
Yagi
Full Yagi antenna design
Yagi
Full Yagi antenna design
Yagi
Full Yagi antenna design
Yagi Antenna
Uses multiple elements for gain and front
Yagi Antenna
Uses multiple elements for gain and front
Yagi Antenna
Uses multiple elements for gain and front
Yagi Boom
Holds Yagi elements in proper alignment
Yagi Boom
Holds Yagi elements in proper alignment
Yagi Boom
Holds Yagi elements in proper alignment
Yagi Element
Includes driven
Yagi Element
Includes driven
Yagi Element
Includes driven
Yagi Gain
Measures performance improvement over dipole
Yagi Gain
Measures performance improvement over dipole
Yagi Gain
Measures performance improvement over dipole
Yagi Stack
Increases gain by stacking multiple Yagis
Yagi Stack
Increases gain by stacking multiple Yagis
Yagi Stack
Increases gain by stacking multiple Yagis
Yardarm Antenna
Mounted on ship’s yardarm for HF/VHF operation
Yardarm Antenna
Mounted on ship’s yardarm for HF/VHF operation
Yardarm Antenna
Mounted on ship’s yardarm for HF/VHF operation
Yaw
Describes rotation around vertical axis in antenna rotators
Yaw
Describes rotation around vertical axis in antenna rotators
Yaw
Describes rotation around vertical axis in antenna rotators
Yaw Rate Sensor
Used in antenna stabilization systems
Yaw Rate Sensor
Used in antenna stabilization systems
Yaw Rate Sensor
Used in antenna stabilization systems
Yield Strength
Maximum stress before permanent deformation
Yield Strength
Maximum stress before permanent deformation
Yield Strength
Maximum stress before permanent deformation
YIG Filter
Uses magnetic tuning for precise frequency control
YIG Filter
Uses magnetic tuning for precise frequency control
YIG Filter
Uses magnetic tuning for precise frequency control
YIG Oscillator
iron
YIG Oscillator
iron
YIG Oscillator
iron
Yin
Dual
Yin
Dual
Yin
Dual
Yoke
Used in CRTs and magnetic field control
Yoke
Used in CRTs and magnetic field control
Yoke
Used in CRTs and magnetic field control
Yoke Mount
Allows rotation and tilt adjustments
Yoke Mount
Allows rotation and tilt adjustments
Yoke Mount
Allows rotation and tilt adjustments
Yottabyte
Equal to 10^24 bytes
Yottabyte
Equal to 10^24 bytes
Yottabyte
Equal to 10^24 bytes
Ytterbium Laser
Used in optical communication and measurement
Ytterbium Laser
Used in optical communication and measurement
Ytterbium Laser
Used in optical communication and measurement
Yttrium Iron Garnet
Used in microwave oscillators and filters
Yttrium Iron Garnet
Used in microwave oscillators and filters
Yttrium Iron Garnet
Used in microwave oscillators and filters
Z Antenna
Compact HF antenna using folded geometry for multiband use
Z Axis
Used in antenna modeling and 3D field plots
Z Band
Used in specialized radar and scientific systems
Z Bridge
Measures complex impedance using AC balancing
Z Energies
related energy states
Z Feed
Ensures proper matching between feedline and antenna
Z Filter
Uses complex impedance networks for shaping response
Z Height
Critical for determining takeoff angle and pattern
Z Line
General term for lines defined by characteristic impedance
Z Load
Represents resistive and reactive components
Z Match
Matches complex impedances using adjustable networks
Z Meter
Measures magnitude and phase of impedance
Z Mode
Describes circuit behavior under specific load conditions
Z Notch
Rejects specific frequencies using impedance cancellation
Z Offset
Adjusts matching by shifting reference point
Z Peak
Occurs at resonance in LC circuits
Z Plane
Used to plot resistance vs. reactance
Z Plot
Visualizes complex impedance across frequency
Z Point
Used in matching and network analysis
Z Ratio
Compares two impedances for matching or transformation
Z Reactance
Represents inductive or capacitive behavior
Z Reflector
Used in antenna arrays for pattern shaping
Z Resonance
Occurs when reactance cancels and impedance is minimum
Z Section
Used in filters and matching networks
Z Series
Combines resistive and reactive elements in series
Z Shunt
Provides bypass or filtering paths
Z Source
RF source with known output impedance
Z Sweep
Plots impedance across frequency range
Z Terminal
Used in balanced and unbalanced systems
Z Tolerance
Acceptable deviation in impedance‑critical components
Z Transformer
Matches two different impedances efficiently
Z Trap
Blocks or passes specific frequencies using tuned impedance
Z Tuner
Matches complex loads to transmitter or feedline
Z Vector
Represents magnitude and phase of impedance
Z Wave
Describes wave behavior in complex media
Z Window
Used in analyzers for Smith chart or numeric view
Z Wire
Used in RF circuits requiring precise characteristics
Zener Diode
Maintains constant voltage across load
Zener Noise
Used in noise generators and randomness sources
Zero Beat
Achieved when two signals produce no audible tone
Zero Bias
bias operating condition
Zero IF
Converts RF directly to baseband without intermediate frequency
Zero Ohm Resistor
Used as PCB link or configuration element
Zero Span
Displays amplitude vs. time at a fixed frequency
Zero Voltage Crossing
Used for low‑noise switching in power circuits
Zigzag Antenna
Provides compact multiband performance
Zinc Oxide Varistor
Protects circuits from voltage spikes
Zipper Noise
Occurs in poorly filtered digital audio systems
Zonal Propagation
Describes signal behavior across geographic zones
ZVS
Reduces switching losses in power electronics
