Hybrid Coupler Utilizing Substrate Integrated Waveguide (SIW) Technology for Ka-Band Applications

Abstract

This paper introduces a hybrid coupler based on SIW technology at 26 GHz and 28 GHz. High losses from the components due to the low wavelength are expected at Ka-band, primarily when planar technology is implemented. Hence, SIW structures are introduced to overcome these losses. A designed coupler based on the direct coupling vias method is proposed in this work. Two rows of vias are implemented with a coupling aperture between them, with cutting in the SIW narrow wall of the SIW. Using this technique benefits in controlling the coupling and the phase differences of the coupler outputs. The designed Coupler is simulated using CST software and metal printed to validate the Coupler's performance. The measured reflection and isolation coefficients are less than -20 dB at 26 GHz and 28 GHz, with transmission coefficients ranging between -2.9 dB and -3.6 dB. The phase differences of -87.2° are observed at the outputs. Overall, the printed SIW coupler has excellent potential for Ka-band applications.

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