Analysis and design of dielectric loaded parallel coupled microstrip quadrature coupler

This paper presents, a wideband 90° hybrid coupler with dielectric loaded microstrip coupled line. The performance of two different hybrid couplers´ design is analyzed by loading the coupled line sections with different dielectric substrates. The dielectric loading is found to improve the wideband performance of hybrid couplers in terms of minimum phase and amplitude imbalances. The simulated results exhibit a coupling of 3 ± 0.7 dB across the band 3.3-10.2 GHz. The return loss and isolation are found to be less than 15 dB with 1.8° phase imbalance. The designed coupler has compact size with dimensions of 30 mm × 20 mm.