Reconfigurable CTS Antenna Fully Integrated in PCB Technology for 5G Backhaul Applications

We present the design and fabrication of a fully integrated continuous transverse stub (CTS)/pillbox antenna for 5G backhaul applications in the E-band. The antenna contains 16 radiating slots excited by a corporate feed network in the parallel-plate waveguide (PPW) technology. These slots are divided into two subarrays of eight slots, each one generating either a sum or a difference pattern along the E-plane. Two pillbox systems are used to feed the two subarrays, and therefore, the radiation patterns can be steered in the H-plane. Such a reconfigurability, both in the E- and H-planes, has not been reported with CTS antennas. Moreover, the recently introduced the substrate-integrated PPW (SI-PPW) technology is used in the printed circuit board technology for complete integration of the antenna module. The structure is thinner than 3 mm, and only low-cost standard fabrication processes are employed for the prototype. The measurement results are in good agreement with simulations. In the E-plane, the sum and difference patterns can cover an angular window of ±10°, and they can be steered in H-plane until ±14° in the complete E-band (71-86 GHz). Over this frequency band, the measured difference pattern exhibits a null depth below -23 dB. The gain remains stable over the band with a maximum of 17.5 dBi and a variation lower than 2.6 dB.