Create equal-split rat-race coupler or 180-degree-ring hybrid
couplerRatrace object to create an equal-split rat-race
coupler or a 180-degree-ring hybrid.
The rat-race coupler is used as a splitter with a phase shift. When given two inputs, the coupler can create sum and difference ports for added and subtracted power. It also acts as an interface between transmitters and receivers for integrating with an antenna and in building circuits with complex functionality like a comparator with sum and difference ports.
There are four ports and the circumference is 1.5
λ. The phase shift
between the output ports is 180 degrees. When you apply an input at port 1, port 2 and port 4
are coupled ports, where the output has a phase difference of 180 degrees, and port 3 is the
isolated port. When you apply an input at port 3, the output is split equally with same phase
at port 2 and port 4.
To analyze the behavioral model for the rat-race coupler, set the
Behavioral property in the
true or 1.
coupler = couplerRatrace creates a rat-race coupler with
default property values for a frequency of 3 GHz.
coupler = couplerRatrace( sets
Properties using one or more
name-value arguments. For example,
couplerRatrace(PortLineLength=0.0286) creates a rat-race coupler
with a port line length of 0.0286 meters. Properties not specified retain their default
PortLineLength — Length of input and output line
0.0186 (default) | positive scalar
Length of the input and the output line in meters, specified as a positive scalar.
coupler = couplerRatrace(PortLineLength=0.0286)
PortLineWidth — Width of input and output line
0.0050 (default) | positive scalar
Width of the input and the output line in meters, specified as a positive scalar.
coupler = couplerRatrace(PortLineWidth=0.0070)
CouplerLineWidth — Width of coupler line
0.0030 (default) | positive scalar
Width of the coupler line in meters, specified as a positive scalar. The default
value is for a
λ/4 line with an impedance of
coupler = couplerRatrace(CouplerLineWidth=0.0070)
Circumference — Length of coupler line
0.1110 (default) | positive scalar
Length of the coupler line in meters, specified as a positive scalar. The default
value is for a 1.5
λ line with an impedance of
coupler = couplerRatrace(Circumference=0.2303)
Height — Height of rat-race coupler from ground plane
0.0016 (default) | positive scalar
Height of the rat-race coupler from the ground plane in meters, specified as a positive scalar.
In the case of a multilayer substrate, you can use the
property to create a rat-race coupler where the two dielectrics interface.
coupler = couplerRatrace(Height=0.0015)
Substrate — Type of dielectric material
Type of dielectric material used as a substrate, specified as a
object. The dielectric material in a
couplerRatrace object with
default properties is Teflon. The thickness of the default dielectric material Teflon is
0.0016 m or the same as the
d = dielectric("FR4");
coupler = couplerRatrace(Substrate=d)
Conductor — Type of metal used in conducting layers
Type of metal used in the conducting layers, specified as a
object. The type of metal in a
couplerRatrace object with default
properties is Copper.
m = metal("PEC");
coupler = couplerRatrace(Conductor=m)
|Calculate and plot charge distribution|
|Calculate coupling factor of coupler|
|Calculate and plot current distribution|
|Design rat-race coupler around specified frequency|
|Calculate directivity of coupler|
|Calculate current at feed port|
|Calculate characteristic impedance of transmission line|
|Calculate isolation of coupler|
|Plot all metal layers and board shape|
|Change and view mesh properties of metal or dielectric in PCB component|
|Extract all metal layer shapes of PCB component|
|Display PCB component structure or PCB shape|
|Calculate S-parameters for RF PCB objects|
Create Default Rat-Race Coupler
Create and view a default rat-race coupler.
ratrace = couplerRatrace
ratrace = couplerRatrace with properties: PortLineLength: 0.0186 PortLineWidth: 0.0050 CouplerLineWidth: 0.0030 Circumference: 0.1110 Height: 0.0016 Substrate: [1x1 dielectric] Conductor: [1x1 metal]
Calculate Current Distribution on Rat-Race Coupler
Create a rat-race coupler with default properties.
coupler = couplerRatrace;
Set the excitation voltage and the phase angle at the ports of the coupler.
v = voltagePort(4)
v = voltagePort with properties: NumPorts: 4 FeedVoltage: [1 0 0 0] FeedPhase: [0 0 0 0] PortImpedance: 50
v.FeedVoltage = [1 0 1 0]
v = voltagePort with properties: NumPorts: 4 FeedVoltage: [1 0 1 0] FeedPhase: [0 0 0 0] PortImpedance: 50
v.FeedPhase = [90 0 270 0]
v = voltagePort with properties: NumPorts: 4 FeedVoltage: [1 0 1 0] FeedPhase: [90 0 270 0] PortImpedance: 50
Calculate and plot the current on the coupler at 3 GHz.
 Pozar, David M. Microwave Engineering. 4th ed. Hoboken, NJ: Wiley, 2012.
Version HistoryIntroduced in R2021b
R2022b: Behavioral Analysis for Rat-Race Coupler
function and the
to perform the behavioral analysis of a rat-race coupler.