RF
TERMS
A
"A"
Carrier
The
non-wire cellular company, that operates in radio frequencies from
824 to 849 MHz.
Acquisition
Time
Amount
of time required for a GPS unit to lock onto 3 satellites to
provide a "2D View" of present position.
Adapter/Adaptor
A
waveguide or coaxial device used to mate two dissimilar
transmission lines or connectors.
ADC
Analog-to-Digital
Converter.
AGC
Automatic
Gain Control - A feedback control circuit which maintains the gain
or output power level of an amplifier constant over a wide range
of input signal levels.
Airtime
Time
spent on a cellular or Digital PCS phone, billed to the subscriber
on a per second or per minute basis.
Alumina
(Aluminum Oxide, Al2O3)
Alumina-ceramic
is used as the substrate material on which is a deposited thin
conductive and resistive layer for thin film microwave integrated
circuits.
AM
Amplitude
modulation; a method of broadcasting in which the desired audio or
video signal modulates the amplitude of a 'carrier' signal.
Analog
Information
that is reproduced using a continuously varying electronic
signal.
Analog-to-Digital
Converter
A
device that converts an analog input voltage to a digital output
word. These are also known as ADCs, and have varying degrees of
input range and output resolution.
Antenna
An
array of metal rods or wires used to intercept radio waves and
convert them into electrical currents. In microwave applications,
often a parabolic reflector with associated feed mechanism.
AM
Noise
The
random and/or systematic variations in output power amplitude.
Usually expressed in terms of dBc in a specified video bandwidth
at a specified frequency removed from the carrier.
AM-PM
Conversion
AM-PM
conversion represents a shift in the phase delay of a signal when
a transistor changes from small-signal to large-signal operating
conditions. This parameter is specified for communications
amplifiers, since AM-PM conversion results in distortion of a
signal waveform.
AMPS
Advanced
Mobile Phone Service, the standard for analog cellular telephones.
ANA
Automatic
Network Analyzer - A computer-controlled test system that measures
microwave devices in terms of their small signal S-parameters. The
use of this instrument by both engineering and production permits
quick and accurate characterization of the input and output
impedance, gain, reverse isolation of individual units and the
degree of match between units.
Analog
The
traditional method of transmitting voice signals where the radio
wave is based on electrical impulses, which occur when speaking
into the phone.
Analog
Driver
An
accessory circuit for an oscillator of filter that permits its
frequency to be changed by a continuously varying signal.
Aspect
Ratio
The
proportions of a TV or film picture, generally given as the ratio
of the width to height. The standard TV picture has an aspect
ratio of 4x3, or 4:3. High-definition video systems may have
aspect ratios of 6x8 or greater.
ATE
Automatic
(or Automated) Test Equipment
ATP
Acceptance
Test Procedure
Attenuator
A
device or network that absorbs part of a signal and transmits the
remainder with a minimum of distortion.
B
"B"
carrier
The
wireline cellular carrier, usually the local telephone company
that operates on the frequencies 869 to 894 MHz.
Back
metallization
Metal
applied to the side of the transistor wafer opposite the active
areas. Provides the collector contact in bipolar transistors and
permits the transistor chips to be bonded to the package or
thin-film circuit substrate.
Balanced
Amplifier
A
transistor amplifier stage in which two identical transistors are
used and the input signal and output power is equally divided
between them. This technique produces approximately twice the
output power of a single transistor stage with generally improved
dynamic range and reduced VSWR.
Balanced
Module
A
gain module of an amplifier that utilizes a 3 dB input splitter
and a 3 dB output coupler to combine the power of two or more
paralleled FET’s. Balanced modules have the characteristics of
good input and output VSWR, and the benefit of indirect stability
under adverse source and load conditions.
Ball
Bond (MIC)
A
bond formed when a ball-shaped end interconnecting wire is
deformed by thermo-compression against a metallized pad. The bond
is also designated a nail head bond from the appearance of the
flattened ball.
Base
Station
The
fixed transmitter/receiver with which a mobile radio transceiver
establishes a communication link to gain access to the
public-switched telephone network.
Bearing
(BRG)
The
precise compass direction (in degrees) from your present position
to the next waypoint. (Readings are selectable in either degrees
magnetic or true north).
Beryllium
Oxide (BeO)
A
ceramic material having very high heat conductivity, good thermal
shock resistance and high strength. Used in metal/ceramic packages
for higher power microwave transistors and as substrates in some
MIC power amplifiers.
BIT/BITE
Built-in
Test/Built-in Test Equipment - Some products have provisions for
connection to customer-supplied test or test equipment that is a
part of the system in which the products are used. Generally, a
military/aerospace term for equipment that contains an automatic
self-testing function.
BPSK
Bi
Phase Shift Keying - A method of modulating a microwave carrier so
that data is translated into 90° phase shifts of the
carrier.
Bonding
Pad (MIC)
A
metallized area at the end of a thin metallic strip to which a
connection is to be made.
Bonding
Wire (MIC)
Fine
gold or aluminum wire for making electrical connections in hybrid
circuits.
C
CAD/CAM
Computer
Aided Design/ Computer Aided Manufacturing
Cascadable
A
device is cascadable if the output port of one such device can be
connected to the input port of another such device without
additional impedance matching being required.
Cascade
A
series of microwave amplifier stages connected in sequence
(sometimes including limiters, attenuators or other elements) to
produce the desired gain, power output and other performance
characteristics.
Cavity
A
metallic enclosure which can be made to resonate at a desired
frequency. Primarily used to describe a cavity filter, which is a
highly-selective tuning element at microwave frequencies that may
be used as the frequency-determining element of an oscillator, or
as a lowpass, bandpass or highpass filter. Generally of fixed
frequency or mechanically tunable over a very limited frequency
range.
C-band
The
portion of the microwave spectrum (4,000-8,000 MHz) used most
widely for distribution of video programs by satellite to cable
systems.
CCIS7
Common
Channel Interoffice Signaling System #7, a CCITT standard
CCITT
Consultative
Committee for International Telephony and Telegraphy
CDPD
Cellular
Digital Packet Data
Cell
The
geographic area served by a single low-power transmitter/receiver.
A cellular system's service area is divided into multiple
"cells".
Ceramic
See:
Beryllium Oxide, Alumina
Certificate
of Compliance
A
document shipped with a customer-ordered product when required by
contract that indicates that the product meets or exceeds all
customer-specified performance characteristics.
Channel
The
width of the spectrum band taken up by a radio signal, usually
measured in kilohertz (kHz). Most analog cellular phones use
30-kHz channels.
Chip
The
uncased and normally leadless form of an electronic component
part, either passive or active, discrete or integrated.
Circuit
The
interconnection of the number of electrical elements and/or
devices, performing desired electrical function.
Circulator
A
passive microwave device consisting of 3-ports that allows the
signal entering each port to pass to the port adjacent to it
(either clockwise or counter-clockwise) but not to the port in the
other direction.
CNR
Carrier-to-Noise
Ratio
Coaxial
Cable
A
cable consisting of one center conductor to carry a signal,
surrounded concentrically (coaxial) by an insulating dielectric
and a separate outer conductor (braid or metal jacket) which acts
as a shield.
Code-Division
Multiple-Access (CDMA)
A
digital technology that uses a low-power signal "spread"
across a wide band-width. A call is assigned a code instead of a
certain frequency. Using the identifying code and a low power
signal, a large number of callers can use the same group of
channels.
Cold
Start
The
process of powering up a new GPS receiver for the first time and
having it search out and lock onto the satellites by itself,
without the benefit of initialization data. This procedure is
slower and may require up to 15 minutes for initial satellite
acquisition only.
Combined
Ripple and Spurious
The
worst case transmission loss (in dB) within the YIG filter 3 dB
passband due to the presence of passband spurious and or passband
ripple responses.
COMSAT
Communication
Satellite Corporation, providing satellite communication services
and chartered by the federal government.
Control
Devices
A
component used to switch, limit, modulate or attenuate microwave
signals.
Conversion
Compression Point (1 dB)
The
specification which states the RF input power (in dBm) at which
the IF output power will increase only 9 dB for a 10 dB increase
in RF input power at stated LO power level. This specification
provides an indication of the mixer two-tone intermodulation
performance and usually is of most concern in high level mixing
applications.
Conversion
Loss
The
ratio (in dB) of the IF output power of a mixer to the RF input
power. All conversion loss measurements and specifications are
normally based on the mixer being installed in a system with
wideband 50 ohm resistive terminations on all ports and a stated
LO signal power level being applied.
Coupler
A
Waveguide device used to sample the microwave transmissions by
means of coupling (combining) signals asymmetrically. May be
of the crossguide or directional variety. Available at
various coupling levels (typically 10 to 50 dB below the signal of
interest).
Course
Over Ground (COG)
The
current direction (in degrees) that a GPS user is actually
traveling, selectable in degrees magnetic or true north.
Crossguide
Coupler
Or
Cross Guide Coupler. See "Coupler"
Cross
Modulation Distortion
The
amount of modulation impressed on an unmodulated carrier when a
signal is simultaneously applied to the RF port of a mixer under
specified operating conditions. The tendency of a mixer to produce
cross modulation is decreased with an increase in conversion
compression point and intercept point.
Cross
Track Error (XTE)
Digital
reading on GPS steering screens that indicates precisely how far
off the user is, to the right or left of the center of the course.
CT-1
Cordless
telephone-first generation; any variety of North American,
European, and Japanese analog cordless telephone.
CT-2
Cordless
telephone-second generation; a digital cordless telephone standard
generally used in residential cordless phone, a telepoint
application, or a small-office WPBX system.
CT-3
Cordless
Telephone 3rd Generation (standards still formative)
CTIA
Cellular
Telecommunications Industry Association
CW
Continuous
Wave - Signal of constant amplitude. Used to differentiate between
the performance of a microwave component for continuous power
levels vs. pulsed signals. For example, "This amplifier will
accept up to +30 dBm CW (or continuous) or up to +50 dBm peak (up
to 5 microsecond duration with low duty cycle) input power without
performance degradation." Also used to describe an
unmodulated carrier.
D
DAC
Digital-to-Analog
Converter.
dB
Decibel
- A logarithmic expression of ratios. Can be found by taking ten
times the common logarithm of the ratio of two power levels, or 20
times the common logarithm of the ratio of two voltage
levels.
dBc
Decibel
related to the signal carrier level
dBm
Decibels
related to 1mW - the standard unit of power level used in
microwave work. For example, 0dBm= 1mW, +10 dBm = 10mW, +20dBm=100
mW, etc.
dBi
Decibels
related to isotropic. Relates the gain of an antenna relative to
an isotropic (perfectly spherical pattern) antenna.
DBS
Direct
Broadcast Satellite; a system that sends TV broadcasts directly
from a communications satellite to home antennas, or dishes.
DCC
Digital
Cross Connect.
Decibel
See
"dB"
Digital
Cross Connect
This
is basically a passive box containing a bunch of chokes that
provides patching and recabling capability. Its primary reason for
existence is that it keeps radio frequency signals from feeding
into digital circuitry.
Digital-to-Analog
Converter
A
device that converts a digital input word to an analog voltage
output. These are also known as DACs, and have varying degrees of
input resolution and range.
Directional
Coupler
See
"Coupler"
DCS
1800
Digital
communication service at 1800 MHz. An extension of the Global
System for Mobile communications (GSM).
DCT
Dynamic
Digital Cordless Telephone
DDS
Digital
Data System
DECT
Digital
European Cordless Telephony (standard)
Desensitization
The
compression in the IF output power from a desired RF input signal
caused by a second high level signal being simultaneously applied
to the RF port of a mixer. As a rule of thumb, in low level
mixers, a desired RF input 3 dB below the mixer conversion
compression point will begin to cause desensitization.
Die
An
uncased discrete or integrated device obtained from a
semiconductor wafer.
Die
Attach
Attachment
of a die or chip to the hybrid substrate.
Dielectric
Resonator
A
high Q, temperature stable ceramic microwave resonator that is
used in microwave oscillator circuits. It can exist in any regular
geometrical form of resonates in various modes at frequencies
determined by its dimensions and shielding conditions.
Dielectric
Resonator Material
Low
loss, high permittivity (Er = 30 to 40) temperature stable ceramic
material. Some of the commonly used materials are barium titanate,
titanium niobiate, etc. The composition of these materials can be
controlled to achieve any frequency variation with temperature
between +10 and -10ppm.
Differential
GPS (DGPS)
A
system devised initially by the U.S. Coast Guard to improve GPS
accuracy levels to within 5 meters. It employs a land-based, fixed
position, DGPS reference receiver to first calculate the Selective
Availability errors, and then transmit the necessary correction
factors to mobile GPS receivers in the area. DGPS systems require
an added beacon receiver to communicate with the standard GPS
unit.
Diffusion
The
phenomenon of movement of matter at the atomic level from regions
of high concentration to regions of low concentration.
Digital
Driver
An
accessory circuit for an oscillator or filter which permits its
frequency to be varied by varying a digital "word." A
digital driver is also an accessory circuit interfacing a switch
or attenuator to a digital command circuit.
Digital
European Cordless Telecommunications
A
digital cordless telecommunications system intended initially for
WPBX applications, later to be used in the home market. DECT
supports both voice and data communications.
Digital
Modulation
A
method of transmitting an analog (continuously variable) signal
using the computer's binary code, 0s and 1s. Digital transmission
offers a cleaner signal than analog technology. Cellular systems
providing digital transmission are currently in operation in
several locations.
Dish
The
parabolic antenna used for transmitting and receiving signals from
communication satellites.
Distortion
Changes
in a signal that involve the addition of spurious tones at
frequencies not present in the original signal. In harmonic
'distortion' the spurious tones are at integral multiples of the
original frequency. In 'intermodulation' distortion, discordant
tones appear at the sums and differences of two original
frequencies.
Distance
To Go (DTG)
Digital
readout (selectable in miles, nautical miles or kilometers)
displayed only when navigating to a waypoint. It simply indicates
the remaining distance from present position to the next waypoint.
DOMSAT
Domestic
communication satellite (as opposed to one confined to military
uses).
Downconverter
Integrated
assembly of components required to convert microwave signals to an
intermediate frequency range for further processing. Generally
consists of an input filter, local oscillator filter, IF filter,
mixer and frequently an LO frequency multiplier, plus one or more
stages of IF amplification. May also incorporate the local
oscillator, AGC/gain compensation components and RF
preamplifier.
Downlink
The
satellite-to-earth microwave channel and related components such
as the earth station receiving equipment. The satellite contains a
downlink transmitter. Downlink components in the earth station are
involved with the reception and processing of
satellite-transmitted signals.
Drive
Level
The
power level of the local oscillator signal applied to the LO port
of a mixer. Operating a mixer with the maximum recommended LO
drive level will result in the best two tone performance, lowest
conversion loss and flattest conversion loss vs. frequency
characteristics, reduced mixer-generated intermodulation products
and will minimize 1/f noise in the output signal. A higher-than
recommended LO power level will result in an increased noise
figure and higher LO feed-through at both the RF and IF ports of
the mixer.
Dry
Nitrogen Filled
A
special process in which a unit is sealed and filled with dry
nitrogen to help prevent fogging and internal corrosion.
DSP
Digital
Signal Processing (or Processors)
DSS
Digital
Sequence Spread Spectrum
Dual-Mode
Phone
A
phone that operates on both analog and digital networks.
dV/dT
Device
voltage temperature coefficient.
Dynamic
Range
The
range from the minimum, which is at a level at or below the
amplifiers' internally-generated noise, to a maximum input signal
level that a component can accept and amplify without distortion.
In regard to mixers, the range of RF input power levels over which
a mixer can operate within a specified range of performance. The
upper limit of the mixer dynamic range is controlled by the
conversion compression point (also a function of LO drive), and
the lower limit is set by the mixer noise figure.
E
EAMPS
Expanded
Advanced Mobile Phone Service
Earth
station
The
ground station that receives (downlink) and sends (uplink) signals
to and from communication satellites.
ECCM
(Military)
Electronic
Counter-Countermeasures - Equipment and techniques to allow
electronic systems such as radar and communications to operate
effectively while attempts are being made to disrupt or jam their
operation.
ECM
(Military)
Electronic
Countermeasures - Equipment and techniques to reduce the
effectiveness of opposing electronic systems such as radar and
communications. Includes techniques such as chaff and barrage
jamming as well as sophisticated methods to deceive the systems
without indication to the opposing operators that their systems
are being affected.
EDI
Electronic
Data Interchange
Electronic
Tuning
The
maximum output frequency deviation that can be achieved without
significantly affecting oscillator performance characteristics.
This is achieved by adjusting the varactor diode coupled to the
dielectric resonator. Typical DSO electronic tuning ranges are
+0.1 of the center frequency.
ELINT
(Military)
Electronic
Intelligence - The intelligence information product of activities
engaged in the collection and processing, for subsequent
intelligence purposes of foreign, non-communications (radar, for
example) electromagnetic radiation. Does not include
communications intelligence (COMINT) or radiation from radioactive
sources such as nuclear detonation.
ESM
(Military)
Electronic
Support Measures - Electronic warfare activities involving the
search for, and interception, location, recording and analysis of,
radiated electromagnetic energy for the purposes of exploitation
in the support of military operations (includes ELINT, SIGINT).
EMI
Electromagnetic
Interference - Unintentional interfering signals generated within
or external to electronic equipment. Typical sources could be
power-line transients, noise from switching-type power supplies
and/or spurious radiation from oscillators. EMI is suppressed with
power-line filtering, shielding, etc.
ENG
Electronic
news gathering; the use of video cameras and tape recorders in
place of film systems for news coverage by TV stations.
E-TDMA
Enhanced
TDMA Access
ETSI
European
Telecommunications Standards Institute. One of the European
organizations responsible for establishing common industry wide
standards for telecommunications.
Eutectic
The
specific proportions of the constituents of an alloy having the
lowest melting point. The system goes from totally molten to
totally solid without going through a slushy range at the eutectic
composition.
EW
(Military)
Electronic
Warfare - Electronic warfare is military action involving the use
of electromagnetic spectrum and actions to retain friendly use of
the electromagnetic spectrum.
F
FCC
Federal
Communications Commission. The U.S. government agency responsible
for allocation of radio spectrum for communication services.
FDMA
Frequency
Division Multiple Access
Ferrite
The
term "ferrite" refers to various iron-containing
compounds. Most commonly, in the field of electronics, the term
refers to cores of various shapes, which are made of these
materials. One of the properties of inductors that have ferrite
cores is that their inductance varies with the current through
them.
Ferrite
Tuner
A
ferrite tuner is a ferrite core inductor that can be used to tune
a resonant circuit.
FET
Field
Effect Transistor - See GaAs FET.
Feedback
Amplifier
Microwave
amplifiers (GaAs FET or bipolar transistor) using negative
feedback in the amplification stages. Used to control input and
output impedance, increase operating bandwidth and help minimize
performance variations caused by inherent variations in transistor
parameters.
FHSS
Frequency
Hopping Spread Spectrum
Field
A
set of scanning lines that, when interlaced with another set,
makes up the 'frame,' or complete TV picture.
Fillet
A
concave junction formed where two surfaces meet.
Flatpack
In
general microwave usage, a miniature hermetic package for MIC
components, designed for a minimum height, with pins for RF and DC
connections existing through the sides (narrowest dimensions), and
designed to be surface mounted or "dropped in" to a
cutout in a micro-strip printed circuit board. The leads and the
largest surface of the package are in parallel planes.
FLOPS
Floating-Point
Operations Per Second
FM
Frequency
modulation
Fmax
Maximum
Frequency of Oscillation - The frequency at which unilateral gain
equals unity.
FM
Noise/Phase Noise
The
short term frequency variations in the output frequency that
appear as energy at frequencies other than the carrier. It is
usually expressed in terms of dBc or as an RMS frequency deviation
in a specified frequency removed from the carrier.
FPLANTS
Future
Public Land Mobile Telecommunications System
Footprint
The
particular patch of the Earth's surface reached by the signal from
a communications satellite.
Frame
A
complete TV picture, comprising two fields. The North American
transmission standard calls for 30 frames transmitted per
second.
Frequency
The
number of cycles per second of an electromagnetic transmission. 1
hertz (Hz) = 1 cycle per second; 1 kilohertz (kHz) = 1,000; 1
megahertz (MHz) = 1,000,000; 1 Gigahertz (GHz) 1 billion.
Frequency
Modulation
A
method of transmission in which the desired signal modulates
(varies) the frequency of a "carrier" signal.
Frequency
Accuracy:
The
maximum output frequency deviation from a specified tuning
function under specified conditions. May be expressed in MHz, PPM,
or PPM/°C.
Frequency
Drift Over Operating Temperature, Max.
The
maximum change in output frequency as a result of a specified
change in operating temperature. In regard to the oscillators, a
measure of the change in frequency over the specified operating
temperature range. It is commonly expressed as parts-per-million
per degree Celsius (PPM/°C) or as a percentage figure. From a
system applications view, the frequency set at room temperature in
+/- total parts per million.
Frequency
Pulling
The
difference between the maximum values of the oscillator frequency
when the phase angle of the load impedance reflection coefficient
varies through 360 degrees. Typically, this load impedance has a
VSWR of 1.67:1.
Frequency
Pushing
The
incremental output frequency change produced by an incremental
change in supply voltage (MHz/V). If supply voltage ripple,
frequency range and amplitude are not specified, measurements will
be conducted at a DC rate.
Frequency
Range
Usually
presented as the minimum and maximum frequencies between which a
particular component will meet all guaranteed specifications.
Frequency
response
The
principal measures of the fidelity of any sound reproducing
device.
Frequency
Reuse
The
use of the same frequency in different geographic areas by
managing the propagation of the frequency. In cellular systems,
their low power allows frequencies assigned to one channel to be
limited to the boundaries of a signal cell. Therefore, the carrier
is free to reuse the frequencies again in other cells in the
system without causing interference. In satellite systems, the use
of directional spot beams similarly allows non-overlapping
geographic areas to reuse the same frequency, and the use of
linear polarized signals allows the use of the same frequency
within the same geographic area.
Fuzzy
logic
A
form of artificial intelligence, stored on a computer chip, that
enables a camcorder or television to make complex adjustments in
focus or picture quality based on ideal models.
Ft
Gain-Bandwidth
Product - (also called transition frequency). It is the frequency
at which the magnitude of the small-signal common-emitter current
gain equals unity.
f3dB
Frequency
at 3 dB Gain Point - The frequency at which gain has reduced 3 dB
from the gain at a specified reference frequency.
G
Gain
flatness
The
variation of gain over a specified frequency range.
GA
Associated
Gain - The tuned gain of a device when it is biased for optimum
noise figure.
GaAs
FET
Gallium
Arsenide Field Effect Transistor - (also called GaAs MESFET for
metal Epitaxial Semiconductor Field Effect Transistor). A field
effect transistor with a reverse-biased Schottky-barrier gate
fabricated on a gallium arsenide substrate. Roughly equivalent to
a silicon MOSFET, GaAs FETs are depletion mode devices. Because
charge carriers reach approximately twice the velocity as in
silicon, for a given geometry a given gain can be reached at about
twice the frequency.
Gain
Block
A
single stage of gain or a cascaded series of gain stages.
Gap
RF
gap in RF cavities.
Geostationary
orbit
The
orbit of a communications satellite that allows it to move at the
precise speed at which the Earth is rotating, thus remaining at
the same spot in the sky relative to the Earth. The orbit is
35,900 km (22,300 mi.) above the Earth and directly over the
equator.
GHz
Gigahertz
(billions of hertz).
Gmax
Maximum
Available Gain - The gain achieved when a transistor is
unconditionally stable and the input and output ports are
simultaneously conjugately matched. Also designated MAG.
GPS
Global
Positioning Satellite
GSM
Global
System for Mobile Communications, or Group Special Mobile - the
Pan-European digital cellular standard
G1dB
1
dB Gain Compression Point - The level of gain from a device which
is 1 dB less than the gain measured under small-signal conditions
for a given input level. See also P1dB.
H
Handoff
Cellular
systems are designed so that a phone call can be initiated while
driving in one cell and continued no matter how many cells are
driven through. The transfer to a new cell, known as a handoff, is
designed to be transparent to the cellular phone user. During a
cellular conversation, when the user reaches the edge of the
service area of a cell, computers in the network assign another
tower in the next cell to provide the phone with continuing
service.
Harmonic
Intermodulation Distortion
The
ratio (in dB) of distortion to the IF output waveform caused by
mixer-generated harmonics of the RF and LO input signals. This
characteristic is extremely dependent on input frequency, RF and
LO signal levels, and the precise impedance characteristics of all
terminations at the operating frequency.
Harmonic
Signals
Signals
which are coherently related to the output frequency. In general,
these signals are integer multiples of the output frequency.
HBT
Haterojunction
Bipolar Transistor Technology
HDTV
High-definition
TV, a technology aimed at producing a video picture containing as
much detail as a 35-mm motion picture, with a wide-screen aspect
ratio and stereophonic sound.
Hertz
The
unit of measuring frequency signals (one cycle per second).
Hybrid
(Junction)
A
transformer or waveguide circuit having four terminals (or four
ports) so arranged that a signal entering at one terminal will
divide and emerge from the two adjacent terminals but will be
unable to reach the opposite terminal. Hybrid Junctions (quadrature
hybrids) are widely used in microwave circuits as power dividers
and combiners (e.g., in balanced amplifiers, double-balanced
mixers).
Hybrid
Integrated Circuits
The
combination of thin-film or thick-film circuitry deposited on
substrates with chip transistors, capacitors and other components.
Thin-film construction is used for microwave integrated circuits (MICs).
Hysteresis
(Electrical)
In
regard to threshold detectors, an upward change in the threshold
voltage to ensure positive switching activity.
Hysteresis
(Magnetic)
The
phenomenon causing the values of the magnetic flux density to lag
behind the values of the magnetizing force so that the increasing
and decreasing fields differ in magnitude. In regard to YIG-Tuned
oscillators, a magnetic lag effect of the magnetic components of a
YIG device that occurs when the tuning coil current is changed.
Hysteresis is measured in terms of the maximum resulting frequency
difference at a particular magnet current when the device is
turned from high to low frequency range.
I
I
dB Gain Compression
(1
dB GCP, Gain Compression Point, P1dB) - The maximum output power
of an amplifier at which amplification is nearly linear (high
power levels result in compression). As input power applied to an
amplifier is increased, some point will be reached where a 10 dB
increase in input signal results in only 9 dB of output signal
increase - this is the 1 dB gain compression point. Other
compression points such as 0.1 dB or 2 dB are sometimes specified.
IDLC
Integrated
Digital Loop Carrier
IF
(Intermediate Frequency)
In
superheterodyne receiving systems, the frequency to which all
selected signals are converted for additional amplification,
filtering and eventual direction.
Image-Reject
Mixer
(or
Image-Rejection Mixer) - A form of branched mixer in which the two
output frequencies (LO + Fin LO - Fin) are separated, isolated and
brought out to separate ports. Thus, as its name implies, this
mixer configuration rejects the undesired mixer image.
Impedance
Opposition
or resistance to the flow of electrical current. Impedance is the
term used in non-direct current (DC) applications, while
resistance is used for DC.
Incidental
FM
The
peak-to-peak variations of the carrier frequency due to external
variations with the unit operating at a fixed frequency at any
point in the tunable frequency range.
Initialization
Refers
to the simple procedure of telling a new GPS receiver "where
it is", when it is turned on for the first time. Information
required includes: approximate present position in
latitude/longitude coordinates; and the current local time and
date.
Insertion
Loss
The
transmission loss measured in dB at that point in the passband
that exhibits the minimum value.
Integrated
Spurious Output Power
The
total power of all spurious outputs in and out of the specified
frequency range.
INTELSAT
International
Telecommunications Satellite Organization; 112-member consortium
of countries formed (1964) to launch and operate communications
satellites.
Intercept
Point
A
figure (expressed in dBm) that indicates the linearity and
distortion characteristics of a microwave component. It represents
the point where the fundamental output and spurious responses
(usually third-order) intersect, when plotted on a log-log scale
with output power ordinate and input power as abscissa.
Intercept
Point 3rd Order
Third
Order Intercept Point (IP3) - The intersection point of the
fundamental Pout vs. Pin extrapolated line and the third-order
intermodulation products extrapolated line. IP3 is highly
dependent on the LO and RF frequency, the LO drive level, and the
impedance characteristics of all terminations at the operating
frequency.
Interconnection
The
conductive path required to achieve connection from a circuit
element to the rest of the circuit.
Interconnections
Those
connections of conductors made within a circuit on the same
substrate.
Ion
Implantation
A
method of semiconductor doping in which selected dopants are
ionized and accelerated at high velocity to penetrate the
semiconductor substrate and become deposited below the surface.
IP3
Third
Order Intercept Point or Intercept Point 3rd Order
IS-41
Interim
Standard 41 - the cellular inter-system handoff and cell delivery
IS-54
Interim
Standard Number 54, the dual-mode (analog and digital) cellular
standard in North America. In the analog mode, IS-54 conforms to
the AMPS standard.
ISDN
Integrated
Services Digital Network. A switched network providing end-to-end
digital connectivity for simultaneous transmission of voice and
data over multiplexed communications channels.
ISM
Industrial,
Scientific, and Medical. It is the unlicensed radio band in North
America and some European countries. It is also refereed to as
part 15.247, the FCC regulation that defines the parameters for
use of the ISM bands in the United States, including power output,
spread-spectrum, and noninterference.
ISO
International
Standards Organization
Isolation
The
ratio (in dB) of the power level applied at one port of a mixer to
the resulting power level at the same frequency appearing at
another port. Commonly specified isolation parameters of mixers
are:
1. LO to RF port: The degree of attenuation of the LO signal
measured at the RF port with the IF port properly terminated.
2. LO to IF port: The degree of attenuation of the LO signal
measured at the IF port with the RF port properly terminated.
3. RF to IF port: The degree of attenuation of the RF signal
measured at the IF port with the LO port properly terminated.
Normally the inverse isolation characteristics (such as RF to LO,
IF to LO, and IF to RF) are essentially equivalent in a
double-balanced mixer.
Isolator
A
device that permits microwave energy to pass in one direction
while providing high isolation to reflected energy in the reverse
direction. Used primarily at the input of communications-band
microwave amplifiers to provide good reverse isolation and
minimize VSWR. Consists of microwave circulator with one port
(port 3) terminated in the characteristic impedance.
J
Jamming
(Military)
The
deliberate radiation, re-radiation or reflection of
electromagnetic energy with the object of impairing the use of
electronic devices, equipment or systems by the enemy. Equipment
may consist of rudimentary CW or noise transmitters, broadband
transmitters or complex systems that generate deceptive signals.
K
kHz
Kilohertz
(thousands of hertz).
Ku-band
The
portion of the microwave spectrum (12,000-18,000 MHz) used in many
newer video satellite transmissions, particularly in Direct
Broadcast Satellite (DBS) systems designed for home reception.
L
LED
Light-emitting
Diode: Solid-state devices that glow when electric current is
applied.
Limiting
Amplifier
Relating
to analog signals and their processing. Also refers to the
operating range of an amplifier where little or no distortion
occurs.
Limiting
Level
The
input power level at which the input/output characteristics
exhibit compression (i.e., the transfer function becomes nonlinear
in that the output increases less than 1 dB for a 1 dB increase in
input).
Linearity
Any
deviation from a best fit straight line approximation under
specified conditions. In regard to YIG-tuned and
voltage-controlled oscillators, the maximum output frequency
deviation from a best fit straight line approximation of the
tuning curve under specified load and constant temperature
conditions. In regard to YIG-tuned filters, the maximum deviation
(in MHz) of the measured resonant frequency vs. coil current curve
from the ideal linear tuning line over the YIG filter's operating
frequency range.
LO
Local
Oscillator - An oscillator used in superheterodyne receiver which
when mixed with an incoming signal results in a sum or difference
frequency equal to the intermediate frequency of the receiver.
LPTV
Low-power
TV; TV station with limited broadcasting range, often built in
rural areas in order to pick up and amplify distant signals. Also
used for broadcast programming to specific audiences.
M
MAG
Maximum
Available Gain - Gain at a frequency where the transistor is
unconditionally stable (k>1) and the input and output ports are
simultaneously, conjugately matched. Also designated: GZ(max),
G(max).
Magnetic
Susceptibility
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