Create coupled microstrip transmission line
coupledMicrostripLine object to create a coupled
microstrip transmission line. Coupled microstrip transmission lines are used to design
directional couplers and filters. The combination of even and odd mode impedances determines
the coupling ratio between the direct arm and the coupled arm.
To analyze the behavioral model for the coupled microstrip line, set the
Behavioral property in the
true or 1.
coupledmicrostrip = coupledMicrostripLine creates a default
coupled microstrip transmission line with a Teflon substrate and default properties for
a resonating frequency of 1.5 GHz.
Length — Length of coupled microstrip line
0.0271 (default) | positive scalar
Length of the coupled microstrip line in meters, specified as a positive scalar.
Width — Width of coupled microstrip line
0.0051 (default) | positive scalar
Width of the coupled microstrip line in meters, specified as a positive scalar.
Spacing — Distance between the direct arm and the coupled arm
0.0046 (default) | positive scalar
Distance between the direct arm and the coupled arm of the coupled microstrip transmission line, specified as a positive scalar in meters.
Height — Height of coupled microstrip line
0.0016 (default) | positive scalar
Height of the coupled microstrip line from the ground plane, specified as a positive
scalar in meters. In the case of a multilayer substrate, use the
Height property to create a coupled microstrip line at the
interface of the two dielectrics.
GroundPlaneWidth — Width of ground plane
0.0300 (default) | positive scalar
Width of the ground plane in meters, specified as a positive scalar.
Substrate — Type of dielectric material
Type of the dielectric material used as a substrate, specified as a
object. The dielectric material in a
with default properties is Teflon. The thickness of the default dielectric material
0.0016 m or the same as the
d = dielectric("FR4");
coupledmicrostrip = coupledMicrostripLine(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
coupledMicrostripLine object with
default properties is PEC.
m = metal("PEC");
IsShielded — Flag to add metal shielding
false or 0 | true or 1
Flag to add a metal shielding to the PCB component, specified as a logical 0 or logical 1.
IsShielded = true or
1 add a metal
To enable FEM solver required for the metal shield property, download the
Integro-Differential Modeling Framework for MATLAB. To download
In the Home tab Environment section, click on Add-Ons. This opens the add-on explorer. You need an active internet connection to download the add-on.
Integro-Differential Modeling Framework for MATLABand click Install.
To verify if the download is successful, runin your MATLAB® session command line.
Shielding — Metal shielding
This property is read-only.
Metal shield for the PCB component, specified as a
The length and width of the box must be equal to the length and width of the ground plane.
The center of the box is at
[0 0 Height]. You can modify the property
after creating the object.
To enable the
Shielding property, set the
IsShielded property to
Connector — Type of RF connector
Type of RF connector assembled at the feed locations of the PCB component, specified as
Example: Create connector from
RFConnector object like this:
coaxial = RFConnector adds a coaxial connector.
To enable the
Connector property, set the
IsShielded property to
|Calculate and plot charge distribution|
|Calculate and plot current distribution|
|Design coupled microstrip transmission line around particular frequency|
|Calculate current at feed port|
|Calculate characteristic impedance of transmission line|
|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 RF connector|
Default Coupled Microstrip Line
Create a default coupled microstrip line.
cml = coupledMicrostripLine
cml = coupledMicrostripLine with properties: Length: 0.0271 Width: 0.0051 Spacing: 0.0046 Height: 0.0016 GroundPlaneWidth: 0.0300 Substrate: [1x1 dielectric] Conductor: [1x1 metal] IsShielded: 0
View the coupled microstrip line.
Multilayer Coupled Microstrip Line
Design and view a coupled microstrip line at the interface of a multilayer dielectric.
cml = design(coupledMicrostripLine,4e9,Z0e=75,Z0o=36); cml.Substrate = dielectric(Name=["Teflon","Teflon"],EpsilonR=[2.1 2.1], ... LossTangent=[0 0],Thickness=[0.8e-3 0.8e-3]); cml.Height = 0.8e-3; show(cml)
Plot the current and charge distribution on the transmission line.
design function to change the even
Zoe) and the odd impedance
Zoo) of the coupled microstrip line.
Increasing the difference between the even impedance (
Zoe) and the odd impedance (
Zoo) decreases the distance between the lines.
Increasing the difference between
Zooincreases the power at the coupled ports.
The impedance of the coupled lines
Zois the geometric mean of
Zoo. If the even and odd impedance values do not satisfy this condition, then calculate the S-parameters using
Zoto get a proper match.
 Pozar, David M. Microwave Engineering. 4th ed. Hoboken, NJ: Wiley, 2012.
 “Microwaves101 | Coupled Line Couplers.” Accessed July 7, 2021. https://www.microwaves101.com/encyclopedias/coupled-line-couplers.
Version HistoryIntroduced in R2021b
R2023b: Metal shielding for coupled microstrip line
Connector properties to add a metal shield to the