A Semicircular Substrate Integrated Waveguide- Based Self-Diplexing Slot Antenna With Polarization Flexibility

The substrate integrated waveguide (SIW) based self-diplexing antenna having polarization flexibility is presented in this letter for satellite communications. The presented self-diplexing antenna can provide the linear polarization, right-hand circular polarization, and left-hand circular polarization at the two closely spaced frequencies with the respective port. The antenna is realized on a semicircular SIW cavity, which is further modified to form the two dominant mode quadrant cavities by incorporating a via wall at the center of the semicircular cavity. The different polarizations are achieved by changing the orientation of the radiating slots. The linear polarization is achieved by loading the curved slots in a back-to-back manner and circular polarization in a crossed manner. The resonant frequencies can be tuned with the help of the length of the slots. The equivalent circuit model of the proposed antenna is developed and the equivalent parameters are extracted. The testing of two fabricated antenna prototypes with different polarizations is presented here.