Compact Wideband LTE Antenna with A Quarter-Mode Cavity-Backed Monopole

A compact hybrid wideband antenna with a quarter-mode cavity and a monopole is proposed for low-cost LTE base station application. The proposed design is very simple. The monopole is featured with an L-shaped structure, which acts as a radiator at high frequency and excites the cavity at low frequency. The combination of the L-shaped monopole and quarter-mode cavity generates two resonance points, achieving a 10 dB impedance bandwidth of 58% (1.69GHz-3.15GHz). Due to the reflection of the cavity, the proposed antenna is slightly unidirectional. The measured results show a gain greater than 2.7dBi from 1.7GHz to 2.7GHz, and an average efficiency greater than -1 dB from 1.7GHz to 2.7GHz is achieved. The proposed antenna is very compact with an overall dimension of 0.26λ_l × 0.22 λ_l × 0.16 λ_l, where λ_l is the free-space wavelength at the lowest operating frequency.

I. Introduction

With the development of 4G/5G wireless communication systems, the wideband antennas covering all the mid-/high LTE band channels with a small size, high efficiency become increasingly popular, due to the extensive range of potential indoor/outdoor applications. Most of the cavity-backed antennas have a very wide impedance bandwidth, however, their size is relatively large.