A Bandwidth-Enlarged and Isolation-Enhanced ZOR MIMO Antenna, Shorter than 0.11λ_g

摘要

A compact bandwidth-broadened and isolation-improved MIMO antenna appropriate for LTE communication employs a small 0.034λ_g long radiator designed to have an in-phase and dense electric field flux at the zeroth order resonance (ZOR) of 2.5 GHz for circumventing the problem of degraded antenna gain and four thin FR4 layers to create closely located resonances for expanding the bandwidth. The radiator is used in the design of two antennas on the top-edge of a MIMO handset with a total length equal to 0.108λ_g (much less than a quarter-wavelength). The two radiating elements are separated by just 10 mm and a folded line between them is optimized to obtain isolation above 10 dB over the 250 MHz bandwidth. The design is validated with a full-wave simulation that is in good agreement with measurements of the fabricated prototype, which uses a low cost FR4 process versus ceramic-based chips or LTCC.