Wideband 5G beamforming printed array clutched by LTE-A 4 × 4-multiple-input–multiple-output antennas with high isolation

A palm-sized antenna is proposed for the hybridisation of fifth generation (5G) and long-term evolution-advanced (LTE-A) communication modes. The antenna has the overall volume of 70 mm ( l ) × 40 mm ( w ) × 0.254 mm ( h ) clutched by four multiple-input-multiple-output chip antennas (CAs) operating at 2.4 GHz for LTE-A on the sides of a flat substrate integrated waveguide (SIW) four-by-four Butler matrix (BM) beamforming antenna operating over the band from 27 to 29 GHz for 5G communication. Advantages are the broad bandwidth gained by a low-profile BM and this metal SIW structure of high isolation above 10 dB with neighbouring CAs, which is impossible for the microstrip BM and coplanar waveguide (CPW) version. The simulated and measured results of the impedance matching as well as the gains and radiated field patterns of all the ports reveal the antenna is proper for the multi-mode communication as a compact geometry. Besides, high isolation between the closely placed radiating elements is observed.