Dual-Band Four-Antenna Module Covering N78/N79 Based on PIFA for 5G Terminals

To satisfy the requirement of the sub-6 GHz bands coverage and the 4 × 4 multiple-input-multiple-output (MIMO) specification for fifth-generation (5G) era, a dual-band four-antenna module covering partial 5G bands N78 (3.4-3.6 GHz) and N79 (4.8-4.9 GHz) is proposed for 5G terminal applications. Based on a quarter-circle-shaped dual-mode slotted planar inverted-F antenna (PIFA), the two target bands are covered by the fundamental TM11 mode and a hybrid higher-order mode combined by quasi-TM11 and quasi-TM0,1/2 modes. The four-antenna module is composed of four such PIFA elements that are arranged in a sequentially rotated layout. It presents a circular shape with a diameter of 39.4 mm and is with a low profile of 1.2 mm. The measured results show that the reflection coefficients of the four elements basically cover the target bands; across N78 and N79, the isolations are better than 8.5 and 17.6 dB for the neighboring elements, and 19.4 and 18.5 dB for the diagonal elements; the average total efficiencies of the four elements are between 38.3% and 39.5% for N78 and 39.3% and 42.6% for N79; all the envelope correlation coefficients are lower than 0.42.