Abstract
The paper presents a novel dual polarized dual fed Vivaldi antenna structure for 1.7–2.7 GHz cellular bands. The radiating element is designed for a base station antenna array with high antenna performance criteria. One radiating element contains two parallel dual fed Vivaldi antennas for one polarization with 65 mm separation. Both Vivaldi antennas for one polarization are excited symmetrically. This means that the amplitudes for both antennas are equal, and the phase difference is zero. The orthogonal polarization is implemented in the same way. The dual polarized dual fed Vivaldi is positioned 15 mm ahead from the reflector to improve directivity. The antenna is designed for -14 dB impedance bandwidth (1.7–2.7 GHz) with better than 25 dB isolation between the antenna ports. The measured total efficiency is better than -0.625 dB (87%) and the antenna presents a flat, approximately 8.5 dB, gain in the direction of boresight over the operating bandwidth whose characteristics promote it among the best antennas in the field. Additionally, the measured cross polarization discrimination (XPD) is between 15 and 30 dB and the 3 dB beamwidth varies between 68° and 75° depending on the studied frequency.
Highlights
An active antenna system (AAS) has been proposed as a technology concept for cellular base stations [1] and it has received much attention from the industrial perspective [2,3,4]
In base station antenna arrays, the radiating elements are linearly oriented along a vertical line, and the array is fed with the fixed power ratio and relative phase with a limited number of beams in the elevation angle
The AAS is interesting from the mobile communications point of view as it offers capacity enhancement, improved network availability, and especially higher energy efficiency for the future wireless communications demands with 3D beam forming capability [5]
Summary
An active antenna system (AAS) has been proposed as a technology concept for cellular base stations [1] and it has received much attention from the industrial perspective [2,3,4]. In base station antenna arrays, the radiating elements are linearly oriented along a vertical line, and the array is fed with the fixed power ratio and relative phase with a limited number of beams in the elevation angle. Active antennas can create and adjust beams inside the mobile base station cell by changing the relative signal phase and amplitude of every radiating element. This letter presents a dual polarized dual fed Vivaldi antenna for 1.7–2.7 GHz frequency band keeping in mind the AAS concept for mobile base stations. The antenna is designed with two parallel dual fed radiating elements for both polarizations to increase the overall aperture of the antenna, and, to increase the directivity.
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