3 Port Circulator S-Matrix | 4 Port Circulator S-Matrix

This page describes 3 Port Circulator S-Matrix (Scattering Matrix) and 4 Port Circulator S-Matrix (Scattering Matrix). It also covers basics of 3 Port and 4-port Circulators.

What are 3-Port circulator and 4-Port Circulator?

Circulator is a multiport device in which RF signal travels from one port to the next in one direction (either clockwise or anti-clockwise) only. Based on number of ports, there are two types of circulator viz. 3-port circulator and 4-port circulator.

rf circulator application note

The figure-1 depicts 3-port RF circulator application note. The signal to be transmitted travels from port-1 to port-2 and signal received at antenna travels from port-2 to port-3 as shown.

3 Port Circulator S-Matrix | 4 Port Circulator S-Matrix

3-port circulator S-matrix, Scattering matrix

The 3 port circulator is formed by a 120 degree H-plane waveguide or by using strip line symmetrical Y junction with a central ferrite disc. 3-port circulator S-matrix can be expressed as follows.
[S] =
|0 0 S13|
|S21 0 0 |
|0 S32 0 |

The figure-2 depicts S matrix of perfectly matched, lossless, non-reciprocal 3 port circulator.

4-port circulator S-matrix, Scattering matrix

The 4 port circulator can be made using two magic-T and a non reciprocal 180 degree phase shifter. It can also be made using a combination of two 3-dB side hole directional couplers with two non reciprocal phase shifters. The figure-3 depicts S matrix of perfectly matched, lossless, non-reciprocal 4 port circulator.

RF Circulator Related Links

3 Port Circulator Vs 4 Port Circulator
RF Circulator Manufacturers
What is RF Circulator
RF Circulator Selection Guide
RF Circulator Application Notes
RF Isolator vs RF Circulator

S-Matrix of other RF devices

3-port and 4-port circulator S-matrix
RF Isolator S-matrix
Magic Tee S-matrix
Rat Race Coupler S-matrix
Branch Line Coupler S-matrix
Directional Coupler S-matrix
Fixed Attenuator S-matrix
Hybrid Ring S-matrix

What is Difference between

difference between FDM and OFDM
Difference between SC-FDMA and OFDM
Difference between SISO and MIMO
Difference between TDD and FDD
Difference between 802.11 standards viz.11-a,11-b,11-g and 11-n
Bluetooth vs zigbee
Fixed wimax vs mobile
wibro vs mobile wimax
Microcontroller vs microprocessor

RF and Wireless Terminologies