60GHz wideband directional coupler with non-radiative dielectric guide

A 60GHz wideband multi-hole directional coupler with hyper non-radiative dielectric guide (HNRD) is proposed and measured results are given. The multi-hole structure between the two HNRD guides is employed to obtain wideband coupling and various and accurate coupling value. Measured results for fabricated couplers showed significantly greater bandwidth and directivity with a much lower coupling loss when compared with directional couplers based on commonly used directional couplers with an NRD guide. Measured results showed that return loss is greater than 16dB, isolation is better than 26dB, and the average coupler loss is 1.1dB, over a percentage bandwidth of 17% at 60GHz.