Low-Loss SISL Patch-Based Phase Shifters and the Mixer Application

This paper proposes a new class of phase shifters using right-angled triangular patches based on the substrate integrated suspended line (SISL) platform. The reference line and the main line of the phase shifter are both designed in the patch form, which is different from previous works. With the common reference patch fixed, multiway and polyphase SISL phase shifters can be achieved by adjusting the main patch. As demonstration, three SISL patch-based phase shifters with phase shifts of 45°, 60°, and 90°, respectively, have been designed at 24-GHz band and fabricated by the printed circuit board (PCB) process. The radiation loss, conductor loss, and dielectric loss of the proposed patch-based phase shifters have been reduced based on the self-packaged SISL platform, and the measured insertion loss of the SISL phase shifter has a typical value of 0.3 dB at 24-GHz band, which is much smaller as compared with the state of the art. Moreover, the 90° case has been applied to an SISL single-balanced mixer design. Besides the low-loss phase shifter, other components of the mixer are all implemented on the common SISL platform with low loss, and the overall loss of the SISL mixer is very small as compared with the other works. The SISL mixer has a compact size and low conversion loss with a minimum of 5.8 dB at the 24-GHz band.