A Wideband Base Station Antenna Element with Stable Radiation Pattern and Reduced Beam Squint

© 2017 IEEE. This paper presents the design procedure, optimization strategy, theoretical analysis, and experimental results of a wideband dual-polarized base station antenna element with superior performance. The proposed antenna element consists of four electric folded dipoles arranged in an octagon shape that are excited simultaneously for each polarization. It provides ±45° slant-polarized radiation that meets all the requirements for base station antenna elements, including stable radiation patterns, low cross polarization level, high port-to-port isolation, and excellent matching across the wide band. The problem of beam squint for beam-tilted arrays is discussed and it is found that the geometry of this element serves to reduce beam squint. Experimental results show that this element has a wide bandwidth of 46.4% from 1.69 to 2.71 GHz with ≥15-dB return loss and 9.8 ± 0.9-dBi gain. Across this wide band, the variations of the half-power-beamwidths of the two polarizations are all within 66.5° ± 5.5°, the port-to-port isolation is >28 dB, the cross-polarization discrimination is >25 dB, and most importantly, the beam squint is <4° with a maximum 10° down-tilt

A Novel Dual-Polarized Planar Antenna

© 2018 IEEE. A wideband dual-polarized antenna with a novel planar configuration is presented for base station applications. Two groups of simple dipoles are fed by two microstrip feed networks to achieve ±45° polarizations. A novel feeding technique that leads to a planar configuration is described. Measured results show that excellent matching and stable radiation performances are achieved over a wide band

Wideband Planarized Dual-Linearly-Polarized Dipole Antenna and Its Integration for Dual-Circularly-Polarized Radiation

© 2002-2011 IEEE. A planarized dual-linearly-polarized (dual-LP) antenna and an integrated dual-circularly-polarized (dual-CP) antenna are proposed in this letter. For the dual-LP antenna, two groups of dipoles are fed by two balun-included feed networks to achieve ±45° polarizations. The feed networks and the radiators are printed on two sides of a substrate, forming a fully planar structure. Taking advantage of its planar configuration, the dual-LP antenna is further integrated with a wideband coupler to realize dual-CP radiation. The coupler is bent and squeezed into the space between the radiators and the reflector, leading to a compact structure. Both the dual-LP antenna and the dual-CP antenna have very stable radiation performances across a wide operating band >66%

Suppression of Cross-Band Scattering in Multiband Antenna Arrays

© 1963-2012 IEEE. This paper presents a novel method of suppressing cross-band scattering in dual-band dual-polarized antenna arrays. The method involves introducing chokes into low-band (LB) elements to suppress high-band (HB) scattering currents. The experimental results show that by inserting LB-pass HB-stop chokes into LB radiators, suppression of induced HB currents on the LB elements is achieved. This greatly reduces the pattern distortion of the HB array caused by the presence of LB elements. The array considered is configured as two columns of HB antennas operating from 1.71 to 2.28 GHz interleaved with a single column of LB antennas operating from 0.82 to 1.0 GHz. The realized array with choked LB element has stable and symmetrical radiation in both HB and LB

A Low-Cost Differentially Driven Dual-Polarized Patch Antenna by Using Open Loop Resonators

A novel differentially driven dual-polarized patch antenna is presented in this communication. The proposed antenna is a low-cost design with a simple configuration, which avoids using the conventional high cost multi-layer PCB technology. The antenna is composed of two intersected open loop resonators, which are connected to each other at the center. By using the electric coupling from the intersected resonators, two orthogonal radiating modes are excited from the top radiating patch. With the even and odd mode current distributions on the intersected resonators, high port isolation and low cross-polarization level are obtained. The external quality factor of the resonator is illustrated by using the analytical model of a double loaded resonator. To demonstrate the design method, the proposed antenna and array are designed, fabricated, and measured. Compared to the traditionally designed capacitively coupled antenna, two times wider impedance bandwidth is obtained for the proposed antenna with high isolation (>38.5 dB) and low cross-polarization level (<-33 dB). The antenna array is designed for 5G base stations, which features the compact size and low reflection coefficient (<-15 dB). In addition, beam scanning performance of the antenna array is also investigated for base station applications

Wideband Dual-Polarized Multiple Beam-Forming Antenna Arrays

© 1963-2012 IEEE. Wideband multibeam antenna arrays based on three-beam Butler matrices are presented in this paper. The proposed beam-forming arrays are particularly suited to increasing the capacity of 4G long-term evolution (LTE) base stations. Although dual-polarized arrays are widely used in LTE base stations, analog beam-forming arrays have not been realized before, due to the huge challenge of achieving wide operating bandwidth and stable array patterns. To tackle these problems, for the first time, we present a novel wideband multiple beam-forming antenna array based on Butler matrices. The described beam-forming networks produce three beams but the methods are applicable to larger networks. The essential part of the beam-forming array is a wideband three-beam Butler matrix, which comprises quadrature couplers and fixed wideband phase shifters. Wideband quadrature and phase shifters are developed using striplines, which provide the required power levels and phase differences at the outputs. To achieve the correct beamwidth and to obtain the required level of crossover between adjacent beams, beam-forming networks consisting of augmented three-beam Butler matrices using power dividers are presented to expand the number of output ports from three to five or six. Dual-polarized, three-beam antenna arrays with five and six elements covering LTE band are developed. Prototypes comprising beam-forming networks and arrays are tested according to LTE base station specification. The test results show close agreement with the simulation ones and compliance with LTE requirements. The designs presented are applicable to a wide range of wideband multibeam arrays

Compact-Size Wideband Antennas and Arrays for Wireless Communications

Polarization is an important parameter for characterizing antenna systems. Dual-polarized and circularly-polarized wideband antennas with compact size are very useful for mobile communications and satellite communications. Due to the multipath propagation and shadowing in urban environment, radio signals received by mobile terminals can become very weak. Dual-polarized antennas can achieve better signal quality in mobile communications by using polarization diversity. Wideband circularly polarized antennas are very important for mobile satellite communications as circularly polarized signals are immune to Faraday rotation effects. Circular polarization also enables mobile satellite communications without strict alignment between transmit and receive antennas. Therefore, dual-polarized antennas and circularly polarized antennas have been drawn increasing popularity in the wireless communication systems. In this thesis, several novel designs of compact, wideband, and specially functioned antennas and arrays are developed for wireless communication applications. First, wideband antennas and arrays are investigated for base station applications with different appealing features, such as compact radiator size, enhanced upper out-of-band suppression, or low pattern sidelobes. They are designed with different novel design concept, such as shared-dipole, electromagnetic dipoles, shorted dipoles, and fourth-order coupling structure. Then, to directly match to the newly emerged differential circuit systems, several wideband differentially fed dual-polarized antennas are proposed for base station applications. They are designed for high common mode suppression, high harmonic suppression, or compact radiator size by using the idea of orthogonal six-port power divider, multi-resonance structure, and crossed open loop resonators. The final designs are two circularly polarized antennas, which have the wide overlapped impedance and axial ratio bandwidth, or dual circularly polarized radiations realized by using crossed open slot-pairs, orthogonal power diver, and phase shift unit cells. The working principles of these different antennas are extensively illustrated with the relevant design theories and detailed structure studies. The performances of these antennas and arrays are evaluated first by the full-wave electromagnetics simulations, and followed by the measurements of the corresponding fabricated prototypes. Good agreements between the simulated and measured results are obtained. With these different features to accommodate different requirements, these antennas and arrays can be the good candidates for the wireless communication systems