Novel Waveguide 3 dB Hybrid With Improved Amplitude Imbalance

We present a new design concept for a 90° waveguide hybrid and its implementation. This novel hybrid design is based on a multiple branch waveguide hybrid. The primary feature of this quadrature waveguide hybrid is the introduction of a controllable ripple in the operational band for achieving a better overall amplitude imbalance. This design concept is verified by implementation of a 90° waveguide hybrid for the 166-208 GHz band and can be used for waveguide hybrids up to several THz. Our simulations indicate that the amplitude imbalance of the designed hybrid is better than 0.11 dB over the most of the 166-208 GHz band with a phase imbalance better than ± 2.3°. Experimental verification of the hybrid shows excellent agreement with simulations with an amplitude imbalance better than 0.15 dB and phase imbalance of ± 2.5° over most of the band being achieved.