Antenna Matching Network Research Articles

Coplanar Side-Fed Tightly Coupled Ultra-Wideband Array for Polar Ice Sounding

We describe a planar ultrawideband (UWB) dual-polarized tightly coupled bowtie antenna array for ground-based polar ice-sounding radar. The array operates over 180–620 MHz with a bandwidth ratio of 3.4:1. The broadband performance is benefitted from the tightly coupled antenna elements. By carefully integrating the impedance matching network into one arm of the bowtie antenna and using a ferrite core for common-mode suppression, this coplanar side-fed array avoids the use of vertical balun and external antenna matching network. The size of the full array is 2.8 m <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times2.8$ </tex-math></inline-formula> m with a weight of only 90 kg, including 24 power distribution boards and 288 feed cables. The thickness of the array is 12.7 cm, which is only about <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.08\lambda $ </tex-math></inline-formula> at the lowest operating frequency. This antenna array was deployed to Greenland in summer 2019 as a part of a surface-based UWB ice-sounding radar to measure and characterize the Greenland ice sheet.

Dual-Band Patch Antenna Matching Network Comprised of Separated Ground Layers and via Posts for Adjustable Return Current Path

This paper proposes a dual-band antenna impedance matching network concept that features identical radiation characteristics. The concept is exemplified for millimeter-wave mobile devices but can be scaled to lower and higher frequency spectrum. The method is deduced through an introduction of an additional matching network consisting of inductive distributed elements to formulate adjustable return current paths. This is realized using fragmented ground plane and a series of vias. No modification of the antenna radiating element is required. This new class of matching network enables independent adjustment of the resonance frequencies while maintaining nearly-identical radiation patterns at both frequencies. For experimental verifications, the proposed antenna impedance matching network is fabricated using a low-temperature co-fired ceramic process. The measurement of this single element exhibits dual-band operations at 28.0 GHz and 39.0 GHz, obtaining the realized gain of 5.15 dBi and 5.42 dBi, respectively. In addition, a 1×4 phased array antenna is devised and studied to validate beamforming performances at both frequencies. With the integration of the beamforming circuit, a reconfigurable beamforming is demonstrated at 28.0 GHz, in which the peak measured gain is 10.83 dBi. At the second resonance frequency (39.0 GHz), a passive feeding network is employed to evaluation its beam scanning abilities, and the main beam peak realized gain of 10.40 dBi is ascertained. The result can be extended to any other frequencies while maintaining near-identical far-field characteristics.

Optimum power transfer in RF front end systems using adaptive impedance matching technique

Matching the antenna’s impedance to the RF-front-end of a wireless communications system is challenging as the impedance varies with its surround environment. Autonomously matching the antenna to the RF-front-end is therefore essential to optimize power transfer and thereby maintain the antenna’s radiation efficiency. This paper presents a theoretical technique for automatically tuning an LC impedance matching network that compensates antenna mismatch presented to the RF-front-end. The proposed technique converges to a matching point without the need of complex mathematical modelling of the system comprising of non-linear control elements. Digital circuitry is used to implement the required matching circuit. Reliable convergence is achieved within the tuning range of the LC-network using control-loops that can independently control the LC impedance. An algorithm based on the proposed technique was used to verify its effectiveness with various antenna loads. Mismatch error of the technique is less than 0.2%. The technique enables speedy convergence (< 5 µs) and is highly accurate for autonomous adaptive antenna matching networks.

Switchable design of a frequency reconfigurable broadband whip antenna in high frequency

AbstractIn this paper, the antenna reconfigurable technology is used to redesign a whip antenna in different sub-bands of high frequency (HF). According to the electrical characteristics of the antenna, on the one hand, two different radiation whip heights are designed to solve the problem of pattern up-warping in the high-frequency band; on the other hand, a common upper loading network and several different adjusting inductors and matching networks are designed for each sub-band to achieve high gain and efficiency when keeping good voltage standing wave ratio (VSWR) characteristics. Five sub-bands of the 10-m HF whip antenna are reconfigured through the actual selection of radiation height, adjusting inductance, and matching network by radio frequency (RF) switch. The antenna load and matching network are optimized by grasshopper optimization algorithm (GOA), and integrated into the antenna body by using the printed circuit technology. The scaled prototype of 1 m frequency reconfigurable antenna is manufactured and tested, which shows that the VSWR is all &lt;3 with an average value of 2.14; the gain is all &gt;−2.5 dB with an average value of 3.90 dB; the efficiency is all &gt;18.2% with an average value of 71.59%, and the patterns all keep horizontal omnidirectional without the phenomenon of up-warping.

Methodology for broadband matching of electrically small antenna using combined non-Foster and passive networks

Decreasing the electric length of an antenna results in increasing its input reactance that becomes greater than its input resistance, resulting in a significant rise in its quality factor and in a drastic reduction of its potential operating bandwidth. For such small antennas, namely ESA for Electrically Small Antenna, passive matching is restricted by the gain-bandwidth theory, providing narrow bandwidths and/or poor gain. This limitation can be overtaken by using antenna matching networks based on non-Foster components. In previous studies, non-Foster components are used to cancel the reactance part of the ESA, and then passive matching may be introduced to transform the net input impedance toward 50Ω, which leads to an increase in the bandwidth. In this paper, a design methodology is put forward on three different topologies all based on combined passive and active matching networks. A described step-by-step design to decrease the antenna quality factor is discussed. A comparison is made between these topologies along with a discussion on their limitations and ability to increase the bandwidth and radiation efficiency of ESA. The third topology presented in this paper is a novel one that proposes a three-stage matching network and exhibits both the widest matched bandwidth and an increase in the efficiency of the whole system compared to previous approaches. In order to make this comparison, a new indicator to estimate the whole system radiated power efficiency is introduced and validated by comparison with a full EM simulation. Moreover, actual implementation of the two most interesting techniques are detailed and associated measured results are carefully compared to simulations.

Gain enhanced conformal patch antenna with defected ground for aircraft applications

This study describes a design of conformal patch antenna for airborne applications especially in measuring the velocity of ocean and river current. By considering the decorrelation time, precipitation, resolution, and size of the antenna, the current system operates within the C-band frequency range of 5.05-5.45 GHz. This design has achieved a bandwidth of 7.7% that helps in increasing the cross-range resolution. A maximum gain of 10 dB is achieved at the bore side angle. The normalised side lobe level (SLL) of -26 dB reduces aliasing by achieving higher pulse repetition rate. Defected ground structure (DGS) is used for suppressing higher harmonics and its effect has been explained with simulation results. As most aircrafts are made of carbon fibre composites (CFC), this antenna has been checked by mounting on CFC sheets for real-time analysis and shows good performance in terms of both measured and simulated results. The transmission line model of the proposed patch antenna and impedance matching network is also described with the corresponding circuits. The characteristic mode analysis is carried out to study the intuitive behaviour and to optimise the performance of patch antenna by analysing the performance metrics of different current modes.

Unbroken Metal Rim MIMO Antenna Utilizing Antenna Clusters

This letter presents an antenna system for mobile devices with an unbroken metal rim. By utilizing the characteristic mode analysis for the unbroken metal rim, efficient multiple-input–multiple-output operation can be achieved. The design is based on an antenna cluster technique that uses several coupled elements that are used to efficiently excite the modes of the rim. Nonresonant antenna elements and matching networks are used to couple to the metal rim. The design has small ground clearance of 5 mm and height of only 4 mm, and can operate in wide bandwidths both in 700–960 MHz low band and 1.56–4 GHz high band. Measurement results confirm that competent performance is achieved.

Optimal Planar Electric Dipole Antennas: Searching for antennas reaching the fundamental bounds on selected metrics

Considerable time is often spent optimizing antennas to meet specific design metrics. Rarely, however, are the resulting antenna designs compared to rigorous physical bounds on those metrics. Here we study the performance of optimized planar meander line antennas with respect to such bounds. Results show that these simple structures meet the lower bound on radiation Q-factor (maximizing single resonance fractional bandwidth), but are far from reaching the associated physical bounds on efficiency. The relative performance of other canonical antenna designs is compared in similar ways, and the quantitative results are connected to intuitions from small antenna design, physical bounds, and matching network design.

Dual Band E and L Shaped Antenna Design with Compact Radiator for 2.5/5.2/5.8 GHz WLAN Application- A Review

In this Paper is Present of Dual-band antenna with a compact radiator for 2.4/5.2/5.8 proposed by optimizing its resonant frequency, Bandwidth of operation and radiation frequency using genetic algorithm. The antenna consists L-shaped and E-shaped radiating element to generate two resonant mode for dual band operation. The above techniques have been successfully used in many applications on communication. Dual band antenna with compact radiator for 2.4/5.2/5.8 GHz WLAN application design and radiator size only width 8mm and length is 11.3 mm [1]. The antenna can we used for various application in field of communication. Genetic algorithm will be used to design the antenna and impedance matching network.

DGPS 기준국 사이트 환경에 따른 안테나 성능 모델링 해석

본 논문에서는 DGPS 단축형 모노폴 안테나와 안테나 사이트 환경을 모델링하여 안테나 주변 환경에 따른 안테나 성능을 분석한다. DGPS 기준국 안테나의 성능 해석을 위한 모델링을 해석하고 대지 도전율이나 전파 장애물에 의한 안테나 성능을 모의 분석하여 DGPS 안테나 설치에 요구되는 사이트 환경을 정립한다. 일정한 접지 면에 적정한 방사형 접지를 갖는 안테나 사이트는 대지 도전율이나 전파 장애물로 인한 안테나 정합회로에 대한 영향은 적으나, 방사 효율 영향은 크게 나타난다. 안정된 DGPS 서비스를 위해서는 안테나 사이트의 양호한 대지 도전율이외에 주변에 전파 장애물이 없는 평탄한 안테나 사이트가 중요하다. Based on the modeling of DGPS antenna and antenna site environment, the DGPS short-monopole antenna performance according to the antenna surrounding environment are analyzed in this paper. The DGPS antenna site modeling that considers the ground conductivity and radio wave obstacles is performed and the general requirements for DGPS antenna site are proposed. In case of antenna site with proper radials on the ground plane of the fixed scale, the effect for antenna matching network due to the ground conductivity and radio wave obstacles is small but the impact on the radiation efficiency is large. To provide the stable DGPS service, it is important to install the DGPS antenna on the flat ground plain with good conductivity and without radio wave obstacles.

DESIGN OF RF ENERGY HARVESTING SYSTEM FOR ENERGIZING LOW POWER DEVICES

Electromagnetic energy harvesting holds a promising future for energizing low power electronic devices in wireless communication circuits. This article presents an RF energy harvesting system that can harvest energy from the ambient surroundings at the downlink radio frequency range of GSM-900 band. The harvesting system is aimed to provide an alternative source of energy for energizing low power devices. The system design consists of three modules: a single wideband 377› E-shaped patch antenna, a pi matching network and a 7-stage voltage doubler circuit. These three modules were fabricated on a single printed circuit board. The antenna and Pi matching network have been optimized through electromagnetic simulation software, Agilent ADS 2009 environment. The uniqueness of the system lies in the partial ground plane and the alignment of induced electric fleld for maximum current ∞ow in the antenna that maximizes the captured RF energy. The design and simulation of the voltage doubler circuit were performed using Multisim software. All the three modules were integrated and fabricated on a double sided FR 4 printed circuit board. The DC voltage obtained from the harvester system in the fleld test at an approximate distance of 50m from GSM cell tower was 2.9V. This voltage was enough to power the STLM20 temperature sensor.

A Genetic and Simulated Annealing Combined Algorithm for Optimization of Wideband Antenna Matching Networks

A genetic and simulated annealing combined algorithm is presented and applied to optimize broadband matching networks for antennas. As a result, advantages of both the genetic algorithm (GA) and simulated annealing (SA) are taken. Effectiveness and efficiency of the presented combined algorithm are demonstrated by optimization of a wideband matching network for a VHF/UHF discone-based antenna. The optimized parameters provide significant improvements of VSWR and transducer power gain for the antenna.

A Lumped Circuit for Wideband Impedance Matching of a Non-Resonant, Short Dipole or Monopole Antenna

A new technique is proposed for wideband impedance matching of short dipole- or monopole-like antennas in the VHF-UHF bands. Instead of constructing the network topology for every particular antenna, we propose a simple network of one fixed topology. This network is an inductive L-section cascaded with a high-pass T-section. The network includes five discrete components-three inductors and two capacitors. Although the approach is not general, the paper proves that matching with the present network is close to the theoretical limit impedance matching confirmed by Bode-Fano theory. The matching performance also approaches the performance of the Carlin's equalizer for short dipoles and monopoles. The dipoles and monopoles may have different shape and different matching bandwidths. By using the matching circuit of fixed topology we avoid greater difficulties related to the practical realization of the Carlin's equalizer. The key point is to minimize the antenna's matching network complexity (and loss) so that the circuit can be designed and constructed in a straightforward manner.

Matching Network Design for a Monopole Antenna Using the Micro-Genetic Algorithm

The design procedure of a novel antenna matching network is proposed to overcome the narrowband characteristics of the monopole antenna. The matching network operating from 156 to 200 MHz is designed based on micro-genetic algorithm (micro-GA). Optional topology and component parameters of the matching network can be determined simultaneously by appropriately coding. The micro-GA iteratively guides a population of randomly selected design candidates toward the optimal solution. Measured results show that voltage standing wave ratio (VSWR) of the antenna system is less than 2.0 and transducer power gain is greater than 88.89% over the desired band.