The paper studies deterministic beamforming for advanced base station antenna technologies including vertical sectorization and array pattern compensation. First, an optimized vertical sectorization beamforming design in terms of low inter-vertical sector interference is proposed. The performance gains in terms of the users' sum rate of the proposed technique against unoptimized vertical sectorization in a simple multi-user system scenario are shown. The work also investigates certain novel beampattern recovery approaches studying the capabilities of advanced base station antenna systems to partially compensate for the distortion caused to the array diagram upon transmit branch failure. The schemes are applied to a speci¿c active antenna product architecture suitable for base stations with advanced beamforming capabilities yet with low hardware complexity and cost footprint.

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.

This paper presents simulation results of a dualpolarized 2x2 element sub-array antenna element at 15 GHz center frequency. The basic idea is to use two waveguides one on the other to excite the orthogonal polarizations by using radiating slots. Above the slots, 4 parasitic patches are set to a form of 2x2 element sub-array. Antenna presents-10 dB impedance bandwidth from 14.3 to 15.6 GHz with better than 68 dB isolation between the excitation ports. At the aforementioned bandwidth, the total efficiency is better than-0.7 dB (> 85%). Antenna shows very good polarization properties and difference between ϕ, θ components is greater than 45 dB. Also the radiation patterns and surface current distributions at 15 GHz center frequency are presented and compared.