A Low-Profile Wideband Antenna With Monopolelike Radiation Characteristics for 4G/5G Indoor Micro Base Station Application
Sichao Wen, Yuandan Dong
Abstract
A wideband, low-profile, vertically polarized antenna with monopole like radiation characteristics is proposed for 4G/5G indoor base station applications. The design of this antenna is based on the traditional monocone antenna with internal matching and reactive load. The structure of monocone is realized by crossed substrate, which reduces the antenna weight and improves the design flexibility simultaneously. Then, reactive loading of capacitively coupled triangle patches and shorting pins are used to reduce the height of antenna profile to 0.08λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">min</sub> , where λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">min</sub> is the free-space wavelength at the lowest operation frequency. An interdigital capacitor is etched near the antenna's input to adjust the impedance matching. The proposed antenna demonstrates consistent monopolelike, omnidirectional radiation patterns within the operating band. A measured impedance bandwidth for voltage standing-wave ratio (VSWR) <; 2.2 of about 81% ranging from 1.66 to 3.95 GHz is achieved, which covers 1.7-2.7 GHz 4G Long-Term Evolution band and 3.3-3.8 GHz 5G N78 band simultaneously. The proposed antenna is tailored for the ceiling micro base station in indoor distributed system.