Triple-Band Microstrip Patch Antenna and its Four-Antenna Module Based on Half-Mode Patch for 5G 4 × 4 MIMO Operation

To meet the demands of the new frequency bands and the
$4\times 4$
multiple-input multiple-output (MIMO) specification brought by fifth generation (5G), a triple-band microstrip patch antenna and its four-antenna module are proposed. Based on the half-mode microstrip patch, the first three modes of TM
_1/2,0
, TM
_1/2,1
, and TM
_3/2,0
that can be independently tuned are engineered to cover the three Chinese 5G bands (N41/N78/N79). The proposed triple-band microstrip patch antenna with the volume of
$33.5\times 32.5\times 4$
mm
³
shows the −6 dB frequency bands of 2.47–2.75 GHz, 3.39–3.60 GHz, and 4.69–5.10 GHz, which makes a nice compromise between antenna volume and impedance bandwidths. Four such patches are arranged in a sequentially rotated style to constitute the triple-band four-antenna module, which is with the volume of
$71\times 71\times 4$
mm
³
. Measured results of the module show high performance. The reflection coefficients of the four elements are almost identical: the bandwidths are 2.50–2.75 GHz, 3.41–3.62 GHz, and 4.68–5.01 GHz; all the isolations are better than −13.3 dB; the average total efficiencies of the four elements are between −1.41 and −1.11 dB, −2.45 and −2.10 dB, and −1.81 and −1.53 dB for N41, N78, and N79, respectively; and all the envelope correlation coefficients (ECCs) are lower than 0.07.