Computational Tools for Millimeter Wave Waveguides
by Paul Chorney
Click on the links
of interest to download the documents described below.
Theoretical Attenuation Calculations
This Excel spreadsheet is designed primarily to provide theoretical attenuation for standard millimeter waveguides. In the upper section of the spreadsheet, the input entries are the WR designation of the waveguide, the operating frequency of interest and the waveguide wall material. The principal output calculation is the attenuation in dB/ft. As side calculations, various other output parameters are calculated that may be of interest, such as guide wavelength and skin depth. Oversized waveguides can also be handled.
In the lower section of the spreadsheet, millimeter waveguides having non-standard dimensions can be handled. The cross-sectional dimensions are entered in place of the WR designation. This lower section can also provide calculations for standard non-millimeter waveguides upon entering the cross-sectional dimensions.
The attenuation formulas are found in many texts. One of these is the old standby, Theodore
Moreno, “Microwave Transmission Design
Data”, Dover Publications, Inc.,
This Excel spreadsheet is useful when the dispersion properties of rectangular waveguides are of interest in communications applications. In the upper section of the spreadsheet, the input entries are the WR designation of the waveguide, the center operating frequency of interest the signal bandwidth and the waveguide length. The principal output is the parabolic phase shift in degrees. As side calculations, various other parameters are calculated, such as group velocity and unit group delay.
In the lower section of the spreadsheet, millimeter waveguides having non-standard dimensions can be handled. The cross-sectional dimensions are entered in place of the WR designation. This lower section can also provide calculations for standard non-millimeter waveguides upon entering the cross-sectional dimensions.
The formulas for group velocity, group delay, and parabolic phase shift are undoubtedly available in many texts. The writer in this case chose to derive the formulas for the academic exercise. This derivation is included in this website as GroupDelayinWaveguides.pdf.
This Excel document is useful when an application is under consideration where thermal isolation is of interest, such as in systems having cryogenic sections. The spreadsheet is designed primarily to calculate the thermal resistance of lengths of millimeter-wave waveguide. The input parameters are the WR designation of the waveguide and the length. Thermal resistance values are given for both standard copper and stainless steel waveguides so that they can be compared. As side calculations, this spreadsheet also compares the insertion loss presented by both materials as the increased loss accompanying the increased thermal resistance could be a design consideration.
The writer also chose to derive the formulas for thermal resistance for the academic exercise. This derivation is included in this website as ThermalResistance.pdf.
This Excel spreadsheet performs the elementary calculation of converting VSWR to return loss, or, conversely, return loss to VSWR. As side calculations, reflection coefficient and reflected power are obtained.
The formulas relating VSWR are so commonplace that the writer has not bothered to include them in this web site. Their relationship is frequently available in table form. The writer prefers using this spreadsheet instead.