A broadband modified rat-race hybrid with around
35% bandwidth is presented in this paper. This hybrid was
developed from 26 to 36 GHz bandwidth (centre frequency 31
GHz) using microstrip technology on Alumina substrate. The
design uses CPWG-Microstrip transitions to measure the
response of the circuit in a coplanar probes station.
Measurements across the frequency bandwidth show a
maximum amplitude imbalance of 0.5 dB, the phase variation is
± 5º, the isolation is better than 25 dB and the return loss is
greater than 10 dB. Moreover, the circuit is planar, easy to
design and consists of a single layer, without requirements of
metallic holes and bonding wires, so it is also a low-cost circuit
