Folded Half Mode Substrate Integrated Waveguide 3 dB Coupler

In this letter, novel compact 3 dB double-slot and single-slot couplers are proposed and implemented based on folded half mode substrate integrated waveguide (FHMSIW). The size of the FHMSIW coupler is reduced by nearly 50% and 75% compared with half-mode substrate integrated waveguide coupler and substrate integrated waveguide coupler, respectively. Prototype couplers at X-band are fabricated and measured and good performance in bandwidth, insertion loss, and balance are achieved.