Continuously tunable crossover based on HMSIW

A frequency-tuning crossover based on half-mode substrate-integrated waveguide (HMSIW) is presented for the first time. Two HMSIW transmission lines are parallelly arranged to form the four-port crossover. Three tunable capacitors placed between the HMSIW transmission lines are used to obtain the tunable passband. For verification, both simulated and measured results are given and good agreement between the simulation and measurement is observed. The measured passband can be tuned in a frequency range from 2.2 to 5.0 GHz (tuning range of 78%) with better than 19 dB return loss and 15 dB isolation, while the insertion loss varies from 0.93 to 1.97 dB.