Microwave & RF Switch Glossary

Contents:

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A

AIRBORNE:
As an operating environment for RF switching equipment, airborn installations typically prioritize compact design and minimal weight and require air-tight construction to withstand high altitudes.

B

BANDWIDTH:
The width of the pass band or operating band of a component. Usually expressed as either the frequency or percentage difference between the lower and upper relative 3 dB points of the frequency response curve.

C

COAXIAL:
An electromagnetic transmission line composed of two concentric conductors seperated by an insulating material. If the outer conductor is truly seamless, such a transmission line is characterized by having no external fields and by having no susceptability to external fields from other sources.
COIL:
An assembly consisting of one or more windings of copper "magnet" wire, usually wound around a form or bobbin, that provides the actuating force to an electromechanical switch or relay's contact assembly.
CONTACT RESISTANCE:
The electrical resistance across closed contacts as measured at their associated external terminals.

D

DPDT:
Double-Pole-Double-Throw switch. A switching with two inputs and two outputs, providing a ON-OFF switching function. Can be thought of as two SPST switches mechanically linked together.
DUTY CYCLE:
The ratio representing the length of time RF power will pass through the switch and the length of time between RF on and off cycles. Usually represented as the percentage of time at full RF power.

E

ENERGIZATION:
The application of power to an actuator coil winding of an electromechanical switch or relay. Use of this word assumes enough power to operate the relay, unless otherwise stated.

F

FAILSAFE:
A switch with an actuator that contains a spring return mechanism to provide RF connection to one selected output when no voltage is supplied to the actuating terminals. Failsafe switches require continuously applied actuator voltage to maintain RF connection at any other position.

G

GROUND STATION:
As an operating environment for RF switching equipment, a ground station is an indoor, stationary installation where reliability and bandwidth are higher priorities than size and weight.

I

IMPEDANCE:
Technically described, the impedance of an electronic device or transmission line is the ratio of the complex (vector) voltage between the conductors (or their equivalent) to the complex (vector) current on the conductors (or their equivalent). Impedance is the AC (vector) equivalent of DC resistance.
INDOORS:
As an operating environment for RF switching equipment, indoors indicates that the equipment will be in an environment with a stable temperature near 60°C and relatively low moisture.
ISOLATION:
RF energy may leak from one conductor to another by radiation, ionization, capacitive coupling, or inductive coupling. In the case of switching devices, isolation is the measurement of the power level of at the unconnected RF output(s) as referred to the power traveling between the input and the connected output. Isolation is normally specified in dB below the input power level.

L

LATCHING:
A switch with a self-cut off actuator that contains a mechanism, either electrical, mechanical or magnetic, that will stop the chosen RF contact path once voltage is maintained on the control terminals after switching is accomplished.

M

MILLIMETER WAVE FREQUENCY RANGE:
The frequency range where the electromagnetic wavelength is between approximately one centimeter and one millimeter in length. Traditionally from approximately 30 GHz to 300 GHz.
MOBILE:
As an operating environment for RF switching equipment, mobile installations tend to prioritize minimal size and weight above other factors.
MULTI-THROW / MULTI-POSITION SWITCH:
A switch with one input and more than two outputs. Standard Logus multi-throw switches provide up to twelve selectable outputs from a single input.

O

OUTDOORS/SHELTERED:
As an operating environment for RF switching equipment, outdoors and sheltered indicate that the equipment will be in an environment with a widely varying temperature and humidity, but protected from rain and direct sunlight.
OUTDOORS/UNSHELTERED:
As an operating environment for RF switching equipment, outdoors and unsheltered indicate that the equipment will be in an environment with a widely varying temperatur and humidity, and exposed to rain and direct sunlight.

P

PULSE LATCHING:
A switch that does not have self-cut off actuator mechanism. The users drive circuit must provide a Pulsed DC Voltage (Non-TTL Compatible switch) or a TTL Level Voltage in order to switch from one position to another. After the unit has switched , the users switch driver then cuts off the voltage.

Pulse Width requirement is 75ms +/- 25ms for a W/G Switch and 50ms nominal for a Coaxial Switch.

R

RETURN LOSS:
The ration, normally expressed in dB, between the power incident upon a load or discontinuity and the power reflected from the load or discontinuity. Also equal to 20 times the log of the reciprocal of the reflection coefficient.

S

SHIPBOARD:
As an operating environment for RF switching equipment, shipboard installation typically prioritize compact design and require weatherproofing even in sheltered installations.
SOURCE IMPEDANCE:
The output impedance of the circuit that drives the component. The impedance of the circuit that the component must work from or be tested in.
SP3T:
Single-Pole-Three-Throw switch. A switch with one input and three outputs. Connects the input to one of the outputs with actuation.
SP4T:
Single-Pole-Four-Throw switch. A switch with one input and four outputs. Connects the input to one of the outputs with actuation.
SP5T:
Single-Pole-Five-Throw switch. A switch with one input and five outputs. Connects the input to one of the outputs with actuation.
SP6T:
Single-Pole-Six-Throw switch. A switch with one input and six outputs. Connects the input to one of the outputs with actuation.
SP7T:
Single-Pole-Seven-Throw switch. A switch with one input and seven outputs. Connects the input to one of the outputs with actuation.
SP8T:
Single-Pole-Eight-Throw switch. A switch with one input and eight outputs. Connects the input to one of the outputs with actuation.
SP9T:
Single-Pole-Nine-Throw switch. A switch with one input and nine outputs. Connects the input to one of the outputs with actuation.
SP10T:
Single-Pole-Ten-Throw switch. A switch with one input and ten outputs. Connects the input to one of the outputs with actuation.
SP11T:
Single-Pole-Eleven-Throw switch. A switch with one input and eleven outputs. Connects the input to one of the outputs with actuation.
SP12T:
Single-Pole-Twelve-Throw switch. A switch with one input and twelve outputs. Connects the input to one of the outputs with actuation.
SPACE:
As an operating environment for RF switching equipment, space is the final frontier of design requirement. Space switches must be able to function at extremely high and low temperatures and in a complete vacuum, with maximum electrical efficiency and minimum size and mass.
SPDT:
Single-Pole-Double-Throw switch. A switch with one input and two outputs. Connects the input to one of the outputs with actuation.
SPST:
Single-Pole-Single-Throw switch. A switch with one input and one output. Provides and ON-OFF switching function with actuation.

V

VSWR:
Volatage Standing Wave Ratio. The measured ratio of the electric field strength at the voltage maximum on a transmission line to the electrical field strength of an adjacent voltage medium.