Electronically-Controlled 35-Bit Substrate Integrated Waveguide Phase Shifter

A 35-bit electronically-controlled digital substrate integrated waveguide (SIW) phase shifter with high phase resolution and large phase shift range is proposed in this paper. The main part of phase shifter contains two rows of metallic vias in each side as the sidewalls of SIW with different waveguide widths, which can be controlled by loading PIN diodes on the inner row of vias. When the diodes are ON, the inner vias are connected and serve as the sidewalls of SIW. When the diodes are OFF, the inner vias are isolated and the outer vias become the sidewalls. This switching mechanism creates two distinct waveguide widths, resulting in different propagation constants. By altering the length of the SIW with various waveguide widths through the PIN diode states, different phase shifts are generated. The working principle of the phase shifter is thoroughly analyzed, and the prototype is fabricated and measured. The results show that at 4.65GHz, the return loss is larger than 10dB, and the insertion loss varies from 1.2dB to 5dB. Within 36 sets of operating states, the phase shifter achieves a large phase shift range of 262° with a phase shift step of 7.3° which means high phase resolution.