Hyperwideband Microwave Crossover Using Bridged Suspended Substrate Line Configuration

A planar microwave crossover is presented. The structure uses a suspended substrate transmission line configuration to cross two independent RF channels. In the central crossed region, one channel is bridged by a conductor on the upper side of the substrate, while the second channel is bridged on the lower side. Two conductive stubs, realized as screws in the fabricated prototype, are placed on both sides of the crossed region to adjust the capacitance in this section and improve the impedance match of each channel. Measurements show that the overall bandwidth of the crossover with less than 0.5-dB insertion loss is from dc to 12 GHz (200% fractional bandwidth). Over this band, the measured return loss and isolation between the two channels are more than 15 and 17 dB, respectively.