A small size planar MIMO LTE antenna system for USB dongle application

A small size planar MIMO LTE antenna for USB dongle application is presented in this paper. The LTE MIMO antenna system consists of two folded inverted-F antennas with an edge to edge separation of 1mm. The dual antenna has a small size with dimensions of 12 × 17 × 1 mm³ and printed on a FR4 substrate (dielectric permittivity of 4.4 and loss tangent of 0.02) of size 41 × 17 × 1 mm³ like a PCB board of USB dongle. The proposed antenna is fed by 50 Ω coaxial cable with IPEX connector. We attach the proposed MIMO antenna system into a 14 inch laptop computer and measure its passive performance which can operate antenna frequency covering LTE band 7, 38 and 40 bandwidth requirements and antenna efficiency all can reach above 45%. By tuning with suitable matching circuit and design, the isolation can keep under −10 dB and the envelope correction coefficient (ECC) performance less than 0.5 between two antennas at frequency from 2300 MHz to 2700 MHz. All simulation data had been simulated by SEMCAD software tool [1], the simulated and measured results are shown to illustrate the high isolation capabilities of the proposed antenna structure.