Analysis and design of a novel waveguide-to-microstrip transition structure at X-Band on HFS S platform

Abstract

An interestingly new structure of waveguide-to- microstrip line transition unit is proposed. Unlike previous works, for the sake of simplicity in fabrication and analysis as well as for less weight, the metal strip of the microstrip line is fed into the waveguide in a four stepped staircase like structure. X-band (8–12GHz) frequency is considered for analysis. The most desirable condition to be achieved is to maximize the transmission coefficient and minimize the reflection coefficient. Using HFSS software, analysis has been done by varying the length and height of the steps. It reveals an encouraging result. Other parameters like number of steps, metallization thickness and width of microstrip, waveguide corss-section etc. have been kept constant. The optimized result considering the steps with height 2.6 mm and length 2.5 mm, shows that the transmission coefficient comes out to be −1dB and return loss as low as -43 dB at 10.62 GHz. Further, the cross-over points, between which the desired condition is achieved for the same specification, ranges from 9.96 GHz to 11.95 GHz. For single carrier frequency based microwave propagation, this model gives inspiring result. Apart from this, multiple carrier frequency based microwave propagation is also possible by selecting a threshold VSWR. In that case also, appreciable frequency band can be obtained using this four stepped staircase-like transition unit.