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Ideal Coaxial-Rectangular Waveguide Transition (TE10): COAXRWG_TE10

Symbol

Summary

COAXRWG_TE10 is a behavioral model that represents an ideal matched transition between transmission lines featuring different characteristic impedances of coaxial and TE10 rectangular waveguide.

Parameters

Name Description Unit Type Default
Wa Rectangular waveguide width Length 22.86 mm
Wb Rectangular waveguide height Length 10.16 mm
Er Relative dielectric constant filling the waveguide   1
Tand Loss tangent of dielectric filling the waveguide   0
*Mur Relative permeability filling the waveguide   1
*Tanm Magnetic loss tangent filling the waveguide   0
*Sigma Dielectric conductivity filling the waveguide Siemens/m 0
ZCoax Coaxial characteristic impedance Resistance 50 ohm
*ZCalc Switch - selector of TE10 characteristic impedance definition ("Power-Voltage"/"Voltage-Current"/"Normalized")   Power-Voltage

* indicates a secondary parameter

Parameter Details

Er, Tand, Mur, Tanm, Sigma. The material properties of the media filling the waveguide.

Zcalc. Allows you to select a definition of characteristic impedance of the TE10 mode propagating in a rectangular waveguide with dimensions Wa*Wb. Options include "Power-Voltage" ,"Voltage-Current", and "Normalized." The default option is "Power-Voltage." This model uses the value of characteristic impedance to denormalize the computed normalized y-matrix of modeled discontinuity. Note that this selection must match the selection of the same parameter in theRWGIRIS_TE10, RWG_TEmn, and RWGT_TEmn elements used around the same schematic.

The characteristic impedance definitions used [1] are:

fc is the cutoff frequency for TEmn and f is the operational frequency; and η is the wave impedance of open space filled with waveguide dielectric.

ZNormalized=1

Implementation Details

COAXRWG_TE10 is implemented as an impedance transformer between two physical transmission lines. The transmission line at port 1 has the frequency-independent user-supplied characteristic impedance of a coaxial line; and the transmission line at port 2 has the frequency-dependent characteristic impedance of a rectangular waveguide with a propagating mode TE10.

Layout

This element does not have an assigned layout cell. You can assign artwork cells to any element. See “Assigning Artwork Cells to Layout of Schematic Elements” for details.

Recommendations for Use

COAXRWG_TE10 provides an ideal match at port 1 if port 2 is terminated to an infinite waveguide. To provide this termination, use RWGT_TEmn (m=1, n=0) model. Alternatively, use PORT_TN port model that refer to a subcircuit containing a single RWGT_TEmn.

Caution: This model is developed to work in a frequency range when only dominant TE10 propagates. It provides reasonable results out of this range, but in this case user discretion is advised.

Normalized characteristic impedance implies that waveguide mode is propagating. This means: Never set ZCalc to "Normalized" if your operational frequency gets into below-cutoff region.

Keep in mind that the results depend on the selected definition of waveguide characteristic impedance.

References

[1] K. C. Gupta, Ramesh Garg, Rakesh Chadha, Computer Aided Design of Microwave Circuits, Artech House, Mass., 1981.

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