Design of a Low-Profile Antenna for Use with 698-2,700 MHz Femtocell Base Stations [Antenna Applications Corner]

A low-profile multiple-input, multiple-output (MIMO) antenna for long-term evolution (LTE) fem-to-cell base stations (BSs) is presented in this article. The antenna element consists of a modified bowtie loaded by three arcs with different lengths that extend the lowest frequency to 698 MHz, a microstrip feeding line, and a planar reflector. It has dimensions of 260 mm × 150 mm × 50 mm and a bandwidth of 698-2,700 MHz. Four of the antenna elements are used to form a four-port MIMO antenna in a novel cross shape. The resulting MIMO antenna has a compact size (480 mm × 480 mm × 50 mm), reasonably low mutual couplings, and extremely low antenna correlations. The MIMO capacity of the proposed antenna is evaluated via numerical simulations, and good MIMO performance is observed.