An E-band Compact Frequency Division Duplex Radio Front-end Based on Gap Waveguide Technology

A compact module consisting of a novel integration of an antenna, a diplexer, and millimeter-wave active circuits for low latency wireless backhaul links working at E-band is presented in this paper. The proposed radio front-end module is built by four distinct layers which are vertically stacked with no electrical contact requirement between them based on gap waveguide technology. A 16×16 corporate-fed slot array antenna is successfully integrated× with a 5^th order diplexer, as well as a transmitter (Tx) and a receiver (Rx) monolithic microwave integrated circuits (MMICs) in one package with a novel architecture and a compact form. The integrated radio front-end is able to simultaneously send and receive data by using a frequency division duplex (FDD) transmission scheme at 71-76 GHz and 81-86 GHz bands. A wireless data transmission is successfully demonstrated showing a data rate of 6 Gbit/s using 64 quadrature amplitude modulated (QAM) signal with a spectral efficiency of 4.4 bit/s/Hz. The proposed radio front-end provides the advantages of low loss, high efficiency, compact integration, and a simple mechanical assembly, which makes it a suitable solution for small cell backhaul links.