The radiation properties of antenna arrays usually employed in radio base stations for mobile communications, as well as the main features of a recently proposed shaped reflector design for that application, are reviewed. Numerical results highlight the comparison of corresponding main coverage performances.

http://ieeexplore.ieee.org/iel5/6965/18753/00866227.pdf

A comparison between coverage performances of usual antenna arrays for radio base stations and a proposed shaped reflector design

A framework for the design and optimization of large dual-linear polarized, shaped-beam reflectarrays for advanced wireless communications is presented. The methodology is based on the generalized intersection approach (IA) algorithm for both phase-only synthesis (POS) and direct optimization of the reflectarray layout, as well as on the use of a method of moments in the spectral domain assuming local periodicity. A thorough description of the design and optimization procedures is provided. To demonstrate the capabilities of the proposed framework, two examples are considered. The first example is a shaped-beam reflectarray for future 5G base stations working in the millimeter waveband, radiating a sectored-beam pattern in azimuth and squared-cosecant pattern in elevation to provide constant power in the coverage area. The second example is a very large contoured-beam reflectarray for direct-to-home (DTH) broadcasting based on real mission requirements with Southern Asia coverage.

/pdf/reflectarray-pattern-optimization-for-advanced-wireless-4b9p9r8fck.pdf

Reflectarray Pattern Optimization for Advanced Wireless Communications

An optimization procedure to design passive metallic reflectors for the fifth-generation (5G) mobile network applications, as well as fabrication and measurement of the designed reflectors, are presented. These reflecting surfaces can be used as passive repeaters in both indoor and outdoor applications to change field coverage by redirecting incident beams into desired directions with relatively controllable power distributions. The design procedure involves an efficient combination of a heuristic optimization method [based on genetic algorithms (GAs)] and a full-wave electromagnetic solver [based on the multilevel fast multipole algorithm (MLFMA)]. The optimized geometries are realized using a 3-D printing method that enables low-cost and adaptive fabrication. During optimizations, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10\lambda $ </tex-math></inline-formula> by <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10\lambda $ </tex-math></inline-formula> compact and efficient reflectors are implemented as reference designs, and they are fabricated to have 18 GHz center frequency of operation. Measurements in a free-space setup are in good agreement with simulations, demonstrating the success of both the design procedure and the designed reflectors as potential 5G components. 

Design, Fabrication, and Measurement of Efficient Beam-Shaping Reflectors for 5G Applications

This paper presents the shaping optimization of an S-band cylindrical offset reflector antenna with cosecant-squared radiation pattern in elevation plane. The cross section of the antenna is mathematically modeled by a polynomial function and optimized by the genetic algorithm to obtain the desired pattern for both TE and TM polarizations. The physical optics method together with the uniform theory of diffraction is used to efficiently calculate the radiation pattern during the optimization. Numerical results show that the cosecant-squared radiation pattern can be achieved with good accuracy for angular span of 50◦. The computed radiation pattern agrees well with method of moments as well as CST software and deviates less than about 0.7 dB, on average, from the ideal cosecant-squared pattern.

http://jce.shahed.ac.ir/article_640_15e91392c7c043f6e216dcaf750db864.pdf

Dual Polarization Synthesis and Optimization of Cylindrical Offset Reflector Antenna for Cosecant-squared Radiation Pattern

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2018RS006623

Design of Shaped Reflector Antennas for the Applications of Outdoor Base Station Antennas in LTE Mobile Communications

New microwave communication services have raised interest in base station antennas capable of radiating an omnidirectional pattern in the azimuthal plane, as is the case for cellular communications. Those antennas usually comprise linear dipole or slot arrays and, at higher frequencies, printed antenna arrays. Although such arrays may produce adequate radiation patterns, the main disadvantages of their use rest on reduced bandwidths and increasing losses with frequency due to phase and power control circuits. Alternatively, at microwave or millimetric ranges, one may employ reflector antenna configurations for base stations, comprising reflector surfaces shaped in order to radiate uniformly in the horizontal plane while taking into account free-space attenuation via cosecant squared-like power patterns in vertical planes, with radiated energy concentrated below the horizon line for reduced interference. The main characteristics of two such configurations are reviewed.

Reflector antenna configurations for radio base stations in cellular communications

A numerical method for the determination of modal fields and propagation constants of metallic waveguides with arbitrary cross-section is developed, based on dyadic Green's functions and the moment method. It results in a representation of the modal fields as a series over orthogonal functions (the eigenfunctions of a rectangular waveguide, circumscribing the waveguide with arbitrary cross-section). Application to ridge, triangular and circular waveguides shows the accuracy of the method.

M.G. Castello Branco

Papers

Reflector antenna configurations for radio base stations in cellular communications

A comparison between coverage performances of usual antenna arrays for radio base stations and a proposed shaped reflector design

A method for the determination of modal fields in waveguides with arbitrary cross-section