Base-Station Antennas in Wireless Communications: A Low-Profile-Loop, Resonator-Loaded Broadband Antenna [Wireless Corner]

A new low-profile antenna is proposed for modern base stations. The low profile of 0.164λ₀ (λ₀ denotes the free wavelength corresponding to the center operating band) is obtained by solving the problems introduced by profile reduction. The concept of an L-shaped radiator-coupling feed-loop resonator is proposed. A new resonance is induced at lower frequency by the loop resonator. The measured results show a wide impedance bandwidth of 33.6% for a voltage standing-wave ratio (VSWR) of less than 1.7 (698–980 MHz) and isolation of more than 30 dB. Stable radiation patterns and gain are achieved over the desired band. In addition, a five-element, low-profile antenna array with different electrical downtilts of 0°–14° is developed for the modern base station. A prototype has been fabricated to verify the proposed design. The antenna array achieves a wide impedance bandwidth of 34.7% (690–980 MHz) for VSWRs of less than 1.7 and stable half-power beamwidth (HPBW) (3-dB beamwidth) of 66° ± 6° at the H-plane (YOZ-plane); antenna gain of 14.2 ± 0.9 dBi is achieved with electrical downtilts of 0°, 7°, and 14°. Owing to these broadband low-profile advantages, the proposed antenna is a promising choice for modern 5G wireless applications.