An Economic Low-profile Elliptical Microstrip Antenna-to-RWG Transition for Microwave Laboratory and X-Band Applications

Abstract

The work presents a low-cost compact microstrip line (MSL)-to-rectangular waveguide (RWG) transition for space communication, satellite communication, RADAR, amateur radio; microwave laboratory X-band applications. A 90˚ MSL-to-RWG transition comprises a MSL and a RWG (WR-90). An elliptical microstrip antenna is used as an RF energy launcher in RWG which is fabricated on a low-cost lossy FR4 epoxy substrate with a loss tangent of 0.02 and a permittivity of 4.4. An impedance mismatch between the 50 Ω MSL and 500 Ω RWG is a challenging task and it has been achieved by changes in the probe geometry, microstrip line (width and length) and by adjusting the dimensions (height, width, and length) of the waveguide slot cut at the bottom end. The impedance matching results in an improved -10dB return loss (RL) with insertion loss (IL) of 2.1 dB at 10.12 GHz and a relative bandwidth of approximately 27% (9.84 GHz-10.38 GHz). An extremely unidirectional with directivity (9.97 dBi) and high gain microstrip antenna (8.24 dBi) has been utilized for electromagnetic energy launch into the WR-90. Therefore the designed MSL-to-RWG transition is a suitable candidate for X-band applications such as microwave laboratory experiment purposes, front end in transmitter/receiver of Space and Satellite applications, RADAR, amateur radio, as a connector for MMIC/MIC circuits and devices. The transition-measured results are also presented.