Ridge waveguide used in microstrip transition
Abstract
It is shown that a ridge waveguide can be used as microstriptowaveguide transition that is easy to fabricate and offers excellent loss characteristics. A quartz substrate is used since it is less lossy than the commonly used alumina substrate. The design of the transition is essentially that of an impedance transformer. A fourstep Chebyshev quarterwave transformer is used. After the desired impedance for each step is determined, a computer program is used to determine the ridgewaveguide dimensions. The impedance of the last section is 50 ohms, and the gap in the ridge is 15 mils, the thickness of the substrate. These two parameters dictate the width of the ridge, which is the same (65 mils) for all four sections. Whereas in theory the first three sections should each be a quarter of a wavelength long, the discontinuities in the ridge at each step give rise to junction capacitances that introduce phase angles to the reflection coefficients.
 Publication:

Microwaves
 Pub Date:
 March 1984
 Bibcode:
 1984MicWa..23..149M
 Keywords:

 Computer Aided Design;
 Impedance Matching;
 Insertion Loss;
 Microstrip Devices;
 Microwave Coupling;
 Rectangular Waveguides;
 Capacitance;
 Frequency Response;
 Joints (Junctions);
 Microwave Transmission;
 Ridges;
 Transmission Loss;
 Electronics and Electrical Engineering