Rf (or microwave) signals have different switching considerations than DC or low-frequency AC signals, including insertion loss, crosstalk, transmission delay, and unterminated stub lines. Therefore, the switching configuration of the RF signal is designed to minimize signal loss and maintain the characteristic impedance through the system. SPnT, cascade, tree, or matrix switches can be used for microwave signal routing.

Expansion switch configuration

Multiplex (two-layer tree switch)

Single channel blocking matrix

Some key electrical specifications to consider when selecting an RF switching system include crosstalk (path isolation), insertion loss, voltage standing wave ratio (VSWR), and bandwidth. When designing an RF switching system, other factors that may affect the performance of the switching system include impedance matching, terminating, power transmission, signal filters, phase distortion, and wiring. The use of switches inevitably degrades the performance of the measurement system, so it is important to consider several key parameters that can significantly affect the performance of the system. In the design phase, costs and benefits are often weighed against each other to get the best solution.

1. Isolation is the direct attenuation of the input and output of the circuit, which is an indicator to measure the effectiveness of the switch cutoff.
2. Insertion loss (also known as transmission loss) is the total power lost when the switch is on. Insertion loss is the most critical parameter because insertion loss can directly lead to the increase of the system noise factor.
3. Switching time refers to the time required for the switch to change from the on-state to the off state and from the off state to the on-state. The time can be up to the number of microseconds of the high-power switch and down to the number of nanoseconds of the low-power high-speed switch. Switching time is most commonly defined as the time required from the time the input control power reaches 50% of its output to the time the final RF output power reaches 90% of its output.
4. Power handling capacity is defined as the maximum RF input power that a switch can withstand without any permanent electrical degradation.

Rf and microwave switch modules can be divided into two categories: electromechanical relay switches and solid-state switches. These switches come in many different forms, from single pole single throw, single pole multiple throw and double pole double throw.

1. Waveguide switch: is a device that can block or distribute electromagnetic waves as needed, applied to microwave signals.
2. Coaxial switch: To achieve the change of permeability, change the transmission constant of the signal, in order to achieve the purpose of switching.
3. High-power coaxial switch: used in airborne electronic interference, space communication, automatic test and communication systems, working in the system to the main and standby transmitter high power output end of the disconnect or on the two states, plays a key role in the safety of the entire system.
4. Matrix switch: applied to data cables, antennas and other automated testing has been wireless receiving terminal, matrix switch stability, durability, small plug loss, simple structure, convenient structure and easy maintenance.