Design Of Feed Network Research Articles

An Eigenmode Correlation‐Based Algorithm for Approaching Antenna Optimal Currents With Multiple Feeds

AbstractA feeding algorithm has been proposed for the excitation of the optimal electric current of Rayleigh quotient form optimization problems. Modal weighting coefficients of the corresponding generalized eigenvalue problem are calculated to form the correlation information between the desired and all other unwanted modes. Based on this information, multiple feeds are arranged to approximate the desired current distributions. The eigencurrent distribution is also utilized for some shape modification to the radiator for a possible feed number reduction. Three canonical optimization problems for electrically small antennas, minimum Q, maximum G/Q, and maximum G are studied and discussed. Several numerical examples with a certain arbitrary shape and electrical size are given. With the proposed feeding algorithm, calculated and simulated current distributions and performance indices are close to the theoretical optimum solution. Finally, a practical feeding network design for a classic characteristic mode problem is shown as a validation.

Design and Analysis of Antenna Feeding Networks Based on the Rotman Lens Using Interval Analysis (IA)

A new method for the design of antenna array feeding networks has been proposed in this work. In particular, the considered feeding networks are based on the Rotman lens. By knowing the maximum errors on the fabrication tolerances, the arithmetic of intervals and interval analysis (IA) are used for determining the lower and upper bounds of the antenna feeding network parameters of interest. Representative and preliminary numerical results are reported to show the potentialities of the proposed method. An experimental X-band Rotman lens prototype has been designed, fabricated, and assessed. The obtained results are quite good.

Design of High-Gain Circularly Polarized Antennas Based on Vehicle Application Environment

In this paper, a novel circularly polarized (CP) antenna that achieves high gain by maximizing the radiation aperture utilization is proposed for vehicle applications. The realization of increasing the radiation aperture is based on the application environment, making full utilization of the vehicle roof, a large metal reflector beneath the antenna, which is indispensable in the vehicle application. Developed from the structure of typical microstrip patch antenna, the design extends the radiation patch to cover the side of the dielectric substrate, which increases the size of the radiating patch without increasing the antenna's outline size. To make CP antennas more suitable for special working environments with large reflecting surface, a sequential rotation feeding structure with 90° progressive phase difference is uniquely designed based on the active port impedance of the four-ended radiation structure. This co-design method introducing the active port impedance of a multi-port radiator into the design of feeding network as the loads can effectively guarantee the CP performance of the antenna, and can greatly simplify the optimization work in the subsequent stage. Based on this design idea, a prototype working at 1.48 GHz with a 50-MHz bandwidth is designed for vehicle satellite broadcasting application. Experimental results show that the antenna achieves a high CP gain greater than 7 dBic with a compact size of $50 \times 50 \times 10\,\,mm^{3}$ ($0.247\lambda _{0} \times 0.247\lambda _{0} \times 0.05\lambda _{0}$ , $\lambda _{0} $ is the wavelength of working frequency in free space).

Feed Network Design Using NewSpace Techniques: Meeting mass, size, cost, and schedule requirements

NewSpace is a term used to describe a new methodology for modern space ventures. This article presents traditional, modern, and NewSpace design methods. Significant reduction in size and mass of satellites can be achieved using NewSpace methodologies.

Broadband feeding networks based on directional filters for two-beam antenna arrays

ABSTRACT An alternative approach for the design of feeding networks designated for two-beam antenna arrays that ensure similar radiation patterns in a very broad frequency range has been proposed. The presented concept is based on directional filters that are utilized for smooth change of excitation signals of two broadband radiating elements and a broadband directional coupler used for ensuring quadrature excitations between two identical parts of the antenna arrays. The proposed concept has been confirmed by measurements of two-beams antenna arrays operating in frequency ratio fH /fL ≈ 2:1 and 3:1.

Array Antenna Feeding Network Design for 5G MIMO Applications

DOI : 10.26650/electrica.2019.19004 Emerging smart antenna systems require different beam patterns of multiple antennas. Although adjustable phase shifters are mostly used in continuous-beam systems, the Butler matrix is used in switching-beam systems due to its low cost and easy fabrication. In this study, an antenna-array-feeding circuit based on the Butler matrix that can be used for Multiple Input Multiple Output applications is designed for 5G new radio. With the proposed switching system, the control of four beams can be achieved. The Butler circuit, designed to cover the 3.5–4.2 GHz 5G band, has a low complexity and is capable of meeting the need for high data throughput. A simulation of the circuit and circuit sub-elements designed using a 0.508-mm-thick substrate material is performed using the Computer Simulation Technology Microwave Studio computer-aided design tool. Furthermore, a prototype of the Butler circuit is fabricated, and the amplitude and phase variations at the output ports are measured. An average transmission loss of the feed circuit is measured as 1.5 dB, and when the length of the Phase Shifter in the circuit is set to λ/8, with a four-element linear array added to the output of the Butler circuit, the main beam is steered to ±15o and ±35o having maximum gain in the 6.39–8.77 dBi range. Cite this article as : Turker Tokan N. Array Antenna Feeding Network Design for 5G MIMO Applications. Electrica, 2019; 19(2): 120-127.

Millimeter-Wave Circularly Polarized Array Antenna Using Substrate-Integrated Gap Waveguide Sequentially Rotating Phase Feed

A substrate-integrated gap waveguide (SIGW) sequentially rotating phase (SRP)-fed 2 × 2 circularly polarized (CP) patch antenna array is presented for the wideband millimeter-wave application. The antenna element is composed of a truncated square patch, SIGW feedline with three layers of printed circuit board (PCB), and another layer of PCB with an air hole for supporting radiation patch. Each radiation patch is driven by an underneath coupling slot etched on SIGW. A wide axial-ratio (AR) bandwidth is achieved by deploying a 2 × 2 SIGW SRP feed network. Moreover, simple calculation expressions of the characteristic impedance and guide wavelength of SIGW are given for the design of SRP feed network. The fabricated prototype shows an impedance bandwidth of 25.6% covering 22.2–28.8 GHz, 3 dB AR bandwidth of 19% from 22.8 to 27.6 GHz, and peak gain of 11.53 dBic.

Design of a simple circularly polarised dual‐frequency reconfigurable microstrip patch antenna array for millimetre‐wave applications

Reconfigurable antenna array has received a lot of attention in present-day wireless communication systems. In this study, a simple design of a four-element circularly polarised dual-frequency reconfigurable microstrip patch antenna array for millimetre-wave applications is proposed. The sequentially rotated series-parallel stub approach is employed in the feeding network design to provide symmetrical array elements positioning, and bringing about a good axial ratio of polarisation. Additionally, a matching branch per element is employed to generate spatial flexibility for element positioning and good impedance matching. Furthermore, due to high-cost constraints of Ka-band RF switches (such as PE42524 SPDT), switches are considered as transmission lines, and are placed within the fractal slots of each elements to reconfigure the frequency. The proposed array operates in two switching states: ON and OFF. Hence, it allows dual-frequency reconfigurability of 27 and 35 GHz for the ON and OFF states, respectively. A full array prototype was then fabricated on a Rogers R5880 substrate and tested in an anechoic chamber. Simulation and measurement results corroborate quite well in general. Patch antenna array gives much better result characterised by reconfigurable behaviour with associated return loss, radiation pattern characteristics, and <; 3 dB axial ratio polarisation bandwidth than the single element. The proposed antenna array finds good applications in radar systems, satellite communications, and aerospace.

Design and Optimization of a Coherent Beamforming Network for an Aperiodic Concentric Ring Array

In this work, a flexible and reconfigurable feeding network design for a nonuniform aperture on circular concentric ring arrays is proposed and analyzed. The network subsystem delivers coherent in-phase outputs with a Gaussian-like amplitude distribution, in a modular and basic topology based on sets of alternated power combiners and dividers. A complete antenna system in a monobeam configuration with a coherent network based on grouped inputs (blocks) per ring for an aperiodic concentric ring array with beam scanning and beam shaping properties is synthesized and analyzed. Additionally, a comparative analysis based on nonuniform and uniform concentric ring arrays fed by the proposed coherent network configuration is conducted and assessed. The optimization of the aperiodic layout on the antenna aperture (radii and interelement antenna spacings) is done by the differential evolution algorithm. Numeric experimentation demonstrates the performance advantages and capabilities of the proposed coherent network configuration with a nonuniform aperture over its uniform counterpart, with an improvement in average equal to −8.7 dB of side lobe level and 3.9 dB of directivity. Furthermore, the numeric examples show a complexity reduction on the coherent feeding network configuration based on the number of control signal inputs compared with a conventional phased antenna array; in the proposed configuration, the main beam is steered and shaped with N-1 control feeding ports per ring in this antenna system.

Shaped Power Pattern Synthesis With Minimization of Dynamic Range Ratio

The problem of synthesizing array patterns while reducing dynamic range ratio (DRR) of complex excitations is of great importance in practical applications since it enables active arrays to be more attractive by appropriately controlling the mutual coupling between the neighboring elements, as well as reducing the cost and complexity of the feeding network design. Unlike the commonly adopted DRR control technique, this paper focuses on minimizing the DRR of the excitations while synthesizing the anticipated array pattern, which results in a new nonconvex and nonlinear optimization problem because of its fractional objective function and nonconvex constraints. By introducing auxiliary variables, we derive an equivalent optimization problem that transforms the fractional objective function into a linear one, decompose the original optimization problem into several subproblems in each iteration, and simplify them as either single-variable quadratic unconstrained optimization or least-squares problems that are solved efficiently in each iteration. Numerical results with different radiation requirements are shown to demonstrate the effectiveness of the proposed scheme.

Near-Field Focused Subarrays in a Multi-Panel Configuration

This paper investigates the focusing features of a multi-panel near-field focused (NFF) antenna. Differently from conventional NFF planar arrays, the proposed configuration is made of a set of NFF subarrays that are concentrically arranged over a cylindrical boundary. A systematic numerical analysis is performed to show how to control the shape of the -3dB focal spot through the main geometrical and electrical parameters of the proposed antenna layout, such as the number of subarrays, the focal spot location of each subarray and the radius of the cylindrical boundary the subarrays are arranged on. When compared with conventional planar NFF arrays, the additional mechanical complexity is partially balanced by a simpler feeding network design and a more symmetric focal spot. Experimental results are shown for a prototype operating at the 2.4 GHz ISM band.

Broadband matrix-type feeding networks for two-beam antennas with constant beamwidth and efficient aperture utilization

ABSTRACTWe report a novel approach for the design of a Butler matrix-type feeding network that allows for achieving two-beam antenna arrays in a very broad frequency range. The proposed solution is based on a 2 × 4 frequency-selective beamforming network which changes its frequency characteristics across the bandwidth. The utilized network features three different properties at three different frequencies. Therefore, such a network allows for achieving two-beam radiation pattern with similar beamwidths and beam directions over 3:1 bandwidth in conjunction with four broadband radiating elements. The presented concept has been verified by the design and measurements of a two-beam antenna array operating in 1–3 GHz frequency range.

Design of a Novel Feeding Network for a Sub-arrayed Monopulse Linear Array Antenna

A modified low-band sub-arrayed feeding network is designed for a monopulse linear array. Instead of using two separate networks for sum and difference channels, one feeding network is designed using genetic algorithm to meet the required specifications. All ports are matched and isolated, and network is lossless and simple. By dividing a 24-element linear array into 3 sub-arrays and using a novel distribution circuit for sub-arrays, a side-lobe level maximum of − 20 dB has been obtained for both channels. Directivity, half-power beamwidth and monopulse slope are approximately identical to those obtained by Taylor and Bayliss distributions for the case when two separate networks have been used in the sum and difference channels on the feeding network. Finally, a comparison of simulation results with measured data shows the validation of the proposed configuration.

A Compact Highly Efficient Hybrid Antenna Array for W-Band Applications

A W -band hybrid array with a compact size and a high efficiency is presented. With the aid of the joint design of the series-shunt feeding network and substrate integrated waveguide (SIW) blocked slots array, the array with 16 × 56 slots can be divided into eight areas, and then the bandwidth of impedance, gain, and radiation pattern can be improved effectively. Moreover, it has both the advantages of low profile over traditional SIW planar array and low loss over traditional air-filled rectangular waveguide (ARW) slot array. Due to the utilization of back-feeding technology of the proposed hybrid array instead of planar SIW divider, it could save a lot of area for radiating energy and lowering the insertion loss, thus resulting in the gain values higher than 30.7 dBi during the entire operational frequency coverage. It is corresponding to the total efficiency of 26.5%, which is higher than the traditional W -band SIW array due to the usage of the back feeding to conserve the radiation acreage and reduce the insertion loss. By designing the SIW slots array and series-shunt feeding network simultaneously, low sidelobe level characteristics of −16 and −20 dB in E - and H -planes have been successfully accomplished, respectively.

Synthesis of the Sparse Uniform-Amplitude Concentric Ring Transmitting Array for Optimal Microwave Power Transmission

Beam capture efficiency (BCE) is one key factor of the overall efficiency for a microwave power transmission (MPT) system, while sparsification of a large-scale transmitting array has a practical significance. If all elements of the transmitting array are excited uniformly, the fabrication, maintenance, and feed network design would be greatly simplified. This paper describes the synthesis method of the sparse uniform-amplitude transmitting array with concentric ring layout using particle swarm optimization (PSO) algorithm while keeping a higher BCE. Based on this method, uniform exciting strategy, reduced number of elements, and a higher BCE are achieved simultaneously for optimal MPT. The numerical results of the sparse uniform-amplitude concentric ring arrays (SUACRAs) optimized by the proposed method are compared with those of the random-located uniform-amplitude array (RLUAA) and the stepped-amplitude array (SAA), both being reported in the literatures for the maximum BCE. Compared to the RLUAA, the SUACRA saves 32% elements with a 1.1% higher BCE. While compared to the SAA, the SUACRA saves 29.1% elements with a bit higher BCE. The proposed SUACRAs have higher BCEs, simple array arrangement and feed network, and could be used as the transmitting array for a large-scale MPT system.

Monopulse array and low side‐lobe level array with a novel feed network

This study presents the methodology design and implementation of a novel feed network. This feed network consists of several ring couplers with miniaturised and wideband characteristics. The size of this coupler is significantly reduced by employing λ /6 sections and open stubs. Besides, wideband performance is achieved by introducing a phase inverter. Compared to traditional ring couplers, the size of the proposed coupler is reduced by nearly 90%, and the relative bandwidth (BW) of the demonstrated ring coupler can reach about 80%. Owing to the miniaturised size and wideband characteristics of this ring coupler, this kind of feed network is much smaller than traditional ones with similar BW. On the basis of this feed network, a monopulse array and a low side-lobe level array is designed and fabricated. Good agreements are achieved between simulations and measurements.

Beampattern synthesis with minimal dynamic range ratio

Abstract The excitations with a small value of dynamic range ratio (DRR) are helpful to control the mutual coupling between array elements, reduce the output power loss, and simplify the feeding network design. Unlike the commonly specified DRR, this communication focuses on finding the minimal DRR of the excitations while synthesizing a desired beampattern. To address this issue, a nonconvex and nonlinear optimization problem is formulated to synthesize array pattern while minimizing the DRR of the excitations, which is solved by extending the penalty method. Firstly, violations of all the inequality constraints are augmented into the original objective function as penalty functions which are nonsmooth. Secondly, a new smooth function is introduced to replace the nonsmooth penalty functions. These operators convert the constrained optimization problem to a smooth unconstrained one which can be easily solved. Theoretical analysis on the approximation error between the constrained optimization problem and the transformed one is provided. Numerical results are also given to verify the proposed scheme in achieving the minimal DRR.

Efficient Millimeter-Wave Antenna Based on the Exploitation of Microstrip Line Discontinuity Radiation

In this paper, a new design perspective utilizes microstrip line discontinuities radiation losses to create an efficient, high-gain millimeter-wave low-profile antenna at 60 GHz. A very compact structure with dimensions of $1.14 \lambda _{o} \times 0.82 \lambda _{o}$ and a substrate thickness of $0.0508 \lambda _{o}$ is proposed. A gain of 11.5 dBi boresight and a 10 dB return loss relative bandwidth of 3.66% (equivalent to 2.2 GHz of bandwidth) have been achieved. Qualitative analysis with simple transmission line theory was used to model the structure. An increase in the relative bandwidth to 11.67%, covering the 60 GHz ISM band (57–64 GHz), has been achieved by tuning the antenna to resonate at multiple resonances within the band of interest. A very high efficiency of 98% has been achieved. The proposed antenna possesses a significant advantage, where it can be employed in a linear antenna array, with a center-to-center distance between adjacent elements greater than half of the free-space wavelength, without producing grating lobes, this reflects positively on reducing the mutual coupling between elements, and gives higher flexibility in the design of feeding network.

Millimeter-wave beam-steering high gain array antenna by utilizing metamaterial zeroth-order resonance elements and Fabry-Perot technique

Millimeter-wave (mm-wave) beam-steering antennas are preferred for reducing the disruptive effects, such as those caused by high atmospheric debilitation in wireless communications systems. In this work, a compact broadband antenna array with a low loss feed network design is introduced. To overcome the short-range effects on mm-wave frequencies, a feed network – with a modified Butler matrix and a compact zeroth-order resonance antenna element – has been designed. Furthermore, the aperture feed technique has been utilized to provide a broadside stable pattern and improve the delivered gain. A Fabry-Perot layer without the height of the air layer is used. Taking advantage of this novel design, a broadband and compact beam-steering array antenna – capable of covering impedance bandwidths (from 33.84 to 36.59 GHz) and scanning a solid angle of about ~94°, with a peak gain of 17.6 dBi – is attained.

Arbitrary Antenna Arrays Without Feed Networks Based on Cavity-Excited Omega-Bianisotropic Metasurfaces

We present a design procedure for low-profile single-feed cavity-excited omega-bianisotropic metasurface antennas (CX-OBMAs), capable of generating an arbitrary desirable field distribution on their aperture. The procedure relies on a greedy algorithm that optimizes the source position inside the cavity and the magnitude and phase of the metasurface modal reflection coefficients, such that the power profile generated by the cavity fields matches the one corresponding to the specified aperture distribution. Once this local power conservation is established, we invoke previously derived analytical formulas to evaluate the (passive lossless) metasurface constituents that facilitate the required field transformation. We demonstrate this scheme by designing CX-OBMAs that generate radiation patterns with prescribed directivity and side-lobe level, for which the aperture fields can be readily stipulated using established antenna array theory. The good agreement between full-wave simulations and semianalytical predictions points out the immense potential of these novel radiators, capable of controlling near- and far-field distributions almost at will. In particular, they can emulate antenna array performance, without requiring design and implementation of complicated, expensive, and lossy feed networks.