Advantages of RF Switch Matrix | Disadvantages of RF Switch Matrix

This page covers advantages and disadvantages of RF Switch Matrices. It mentions benefits or advantages of RF Switch Matrix and drawbacks or disadvantages of RF Switch Matrix.

What is RF Switch Matrices ?

Introduction:
RF switch matrix contains RF switches (Electro-Mechanical or Solid State) in a mechanical box with multiple inputs and outputs used to route the RF signals. In addition to RF switches, it contains signal conditioning components such as attenuators, amplifiers, filters, couplers, dividers/combiners etc.

RF switch matrix can be mainly categorized into following two types.
Blocking type : It is developed using all RF switches. In this type, input signal can only be connected to single output port. This input port is blocked from use by all other output ports. Moreover unused ports block connectivity to all other RF switches. RF switches in different configurations are used such as SPST, 1P2T (i.e. SPDT), 1P3T, 1P4T, 1P6T etc.
Non-blocking type : It is constructed using RF switches, RF power combiners/dividers. Here each input port is available to all output ports inspite of it being connected with to an output port. JFW Industries, Inc. is the leader in manufacturing of RF switch matrices for various applications.

Image Courtesy : JFW Industries, Inc., Indianapolis, IN 46237, Visit : www.jfwindustries.com

Following are some of the applications of RF switch matrices.
• 16:1 Switch matrix used to route multiple satellite TV feeds to RF spectrum analyzer for signal integrity testing. The design houses five nos. of SP4T coaxial Electro-mechanical switches.
• Switch matrix used to measure jitter of multiple high speed serial data links simultaneously
• TV reception and re-broadcasting
• Test and Measurement of Transmit/Receive functionalities of DUT (Device Under Test) using RFSG (RF Signal Generator) and RFSA (RF Signal Analyzer/ Spectrum Analyzer/ Frequency counter/ Power meter).
• Satellite Ground Station Systems at Hub station e.g. Modem SWO (Switch Over Unit), Frequency Converter SWOs for Up converter and down converter etc.

The figure-1 depicts block diagram of RF switch matrix modules.
• RF Signal routing and conditioning : It uses RF switches and RF flexible or rigid cables for RF signal routing. RF switches can be chosen either Electro-mechanical type or Solid State type based on desired specifications. Electro-Mechanical RF switches depend on mechanical contacts for switching operation. Solid State RF switches use devices such as PIN diodes, GaAs FET or combination of both for switching. RF signal conditioning components include RF amplifiers, attenuators, filters, power splitters, directional couplers, mixers etc. Based on impedance, input and output connectors can be of various types viz. SMA, BNC, N-type etc.
• Microcontroller hardware and software : Microcontroller IC such as STM32L4 series or LPC2148 can be used as per custom RF switch matrix design. Based on size of the source code and data in the program external EPROM and/or flash RAM are used.
• Matrix switch or Keypad : Usually 4x4 keypad is used for providing user input for monitor and control of the RF switch matrix.
• LCD/LED display : Appropriate LCD/LED display is used for providing menu to the user for various operations.
• DC power supply : It provides supply voltages to RF switches, microcontroller driver, keypad, LCD/LED display etc.
• Interfaces : Based on the design various serial interfaces such as RS232, RS485 are used. Ethernet port is provided for remote monitor and control using TCP/IP protocols.

Benefits or advantages of RF Switch Matrix

Following are the benefits or advantages of RF Switch Matrix:
➨It brings connections of all the test equipments to one central place. This allows DUT testing easier and quick.
➨Measurement is done automatically and results are stored in files with minimal manual connections. Hence measurements can be carried out in less time and does not require presence of man power all the time.
➨Calibration is easy to characterize due to short signal path between DUT and test equipment (VSA-Vector Signal Analyzer or VSG-Vector Signal Generator).
➨As DUT and test equipments are closer, it reduces path loss and signal degradation. Hence receiver sensitivity requirements of the test equipments (spectrum analyzer, network analyzer, VSA) can be met.
➨It can be remotely monitored and controlled using LAN Ethernet port. Testing can also be done from remote end once DUT is connected with the set up and power is ON. Hence test lab in one country can easily be accessed by multiple test engineers from across the globe.

Drawbacks or disadvantages of RF Switch Matrix

Following are the drawbacks or disadvantages of RF Switch Matrix:
➨Port to port isolation should be higher otherwise results are not accurate.
➨Insertion loss is higher in non-blocking type of RF switch matrix compare to blocking type.
➨Readily available RF switch matrices may not meet your testing requirements, In such situation, Switch matrix should be custom designed at the cost of labour and money.
➨To operate the RF switch matrix for different applications, training should be given to the test technicians.

Also refer following RF switch related articles, terminologies and more.
• What is RF Switch
• RF Switch application notes
• RF Switch manufacturers
• Absorptive RF Switch vs Reflective RF Switch
• Electro Mechanical RF Switch versus Solid State RF Switch
• FET versus PIN diode RF Switch
• RF Switch selection guide
• RF Switch types
• RF Switch working with equivalent circuit

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