Voltage Standing Wave Ratio Bandwidth Research Articles

A Low-Profile Wideband Antenna With Monopolelike Radiation Characteristics for 4G/5G Indoor Micro Base Station Application

A wideband, low-profile, vertically polarized antenna with monopolelike radiation characteristics is proposed for 4G/5G indoor base station applications. The design of this antenna is based on the traditional monocone antenna with internal matching and reactive load. The structure of monocone is realized by crossed substrate, which reduces the antenna weight and improves the design flexibility simultaneously. Then, reactive loading of capacitively coupled triangle patches and shorting pins are used to reduce the height of antenna profile to 0.08 λ min, where λ min is the free-space wavelength at the lowest operation frequency. An interdigital capacitor is etched near the antenna's input to adjust the impedance matching. The proposed antenna demonstrates consistent monopolelike, omnidirectional radiation patterns within the operating band. A measured impedance bandwidth for voltage standing-wave ratio (VSWR) < 2.2 of about 81% ranging from 1.66 to 3.95 GHz is achieved, which covers 1.7–2.7 GHz 4G Long-Term Evolution band and 3.3–3.8 GHz 5G N78 band simultaneously. The proposed antenna is tailored for the ceiling micro base station in indoor distributed system.

Heptagonal Shaped UWB Antenna with DGS for Wireless LTE with Enhanced Bandwidth

The paper discusses about the implementation of Heptagonal shaped compact ultra-wideband planar Microstrip patch antenna with and without defected ground plane structure (DGS) with analysis of various parameters like return loss, VSWR bandwidth etc. A substrate made up of dielectric constant FR4 epoxy is utilized and the 2D and 3D radiation pattern are also discussed. DGS has helped to fine tune and increase the bandwidth &amp; its effects have been studied. A volume of 28x32x1.7 (1523.2 mm^3) is occupied by the size of antenna with dielectric constant of εr = 4.4, tanδ= 0.02. In order to provide fine tuning in the return loss graph, a 50Ω line with width of W=3mm direct line feeding method has been used for the micro-strip line and slots have been introduced in the ground plane structure, for achieving the good bandwidth coupling between the slots plays an important role. The antenna parameters including VSWR, Gain and return losses v/s frequency effects for the antenna with variation of slots and dimensions has been studied in this paper along with the analysis of important parameters such as return loss (dB), bandwidth, VSWR (Voltage Standing Wave Ratio) of patch antenna which has been performed using Ansoft HFSS v15 tool. The proposed design of the heptagonal shaped antenna operates as an ultra-wide band antenna ranging from 3.20 GHz to 10 GHz and beyond covering most of applications from LTE, Wimax (3.5/5.55GHz), Radio altimeter, RFID and ISM WLAN 5.2/5.8GHz etc.

Wideband microstrip magnetoelectric dipole antenna with stripline aperture‐coupled excitation

A novel wideband microstrip magnetoelectric (ME) dipole antenna excited by a stripline aperture-coupled feeding structure is proposed and demonstrated. An antenna prototype is fabricated with low-cost standard printed circuit board process on three substrates and tested. Measured results show that an impedance bandwidth for voltage standing wave ratio (VSWR) <; 2 is ~42% (10.2-15.6 GHz), and a measured boresight gain is ~7.8 ± 0.7 dBi. Almost stable and symmetrical unidirectional radiation patterns with low in cross-polarization and backward radiation are obtained over the entire operating frequency band. By employing the proposed radiating element, two types of cavity (one is a square cavity, the other is a circular cavity) are introduced for enhancing the antenna gain and investigated. After analysis, a better one is chosen to be fabricated and measured. A measured impedance bandwidth for VSWR <; 2 is ~45% (10.1-15.9GHz), and a measured boresight gain is ~8.9 ± 0.5 dBi. The measured average gain is ~1.1 dBi larger than that of the radiating element. The measured radiation patterns, cross-polarization levels and half power beam width are almost the same as that of the radiating element except that the measured front-to-back ratios are improved several decibels.

Dual‐resonance‐based wideband antenna for integrated module applications

A wideband module antenna comprised of a small ground radiation antenna in the module and a parasitic radiation loop in the evaluation board is proposed. Unlike conventional ground radiation antennas, the ground radiation antenna in the module works as an exciter to the parasitic radiation loop, which further couples with the evaluation board as a radiator. Thus, a space-saving antenna is obtained with wide bandwidth and easy tuning. Accordingly, dual resonance can be generated by tuning the resonant frequencies of the ground radiation antenna and the parasitic radiation loop equally. When measured, the antennas have wide bandwidths (2:1 voltage standing wave ratio bandwidth of 270 MHz) and high efficiency (ranging from 44 to 74%).

Circularly polarised multiservice RFID antenna

A multiservice radio-frequency identification (RFID) antenna with wideband axial ratio (AR) response around 2.4 GHz is presented in this study. This antenna offers dual band operation. The prototype follows a configuration constituting a driven element (radiator) and a parasitic element. The first band offers a voltage standing wave ratio (VSWR) bandwidth (3:1) of 183 MHz (0.85–1.04 GHz). The VSWR bandwidth (3:1) for the second band is 2.77 GHz (2–4.77 GHz). It also offers a 3 dB AR bandwidth of 1.1 GHz (2.1–3.2 GHz). The 2:1 VSWR bandwidth of 0.9 GHz (2.1–3 GHz) and cross-polarisation in the second band makes this antenna suitable for 2.4 GHz RFID reader applications. The other services supported by the proposed antenna include global system for mobile communication (0.88–0.96 GHz), long-term evolution (2.3–2.4 GHz), wireless fidelity (2.4–2.5 GHz), bluetooth low energy (2.4 GHz) and worldwide interoperability for microwave access (3.5 GHz). To extract the multiservice characteristics, it is necessary to integrate this antenna to a handheld computing platform. For assessing the performance in such a platform, the prototype is optimised and merged with a larger ground plane of size 170 mm × 130 mm and studied in the course of this study.

Matching permeability and permittivity of Ni0.5Zn0.3Co0.2In0.1Fe1.9O4 ferrite for substrate of large bandwidth miniaturized antenna

Nickel zinc cobalt indium ferrite of nominal composition Ni0.5Zn0.3Co0.2In0.1Fe1.9O4 was synthesized by a co-precipitation technique. The effect of sintering temperature on structural and electromagnetic properties was studied over the frequency range of 10 MHz to 6 GHz. The crystallite size increases from 45 to 60 nm, with an increase in sintering temperature from 800 to 1000 °C. The relative permeability (μr) and relative permittivity (er), both varies between 5 and 8 with sintering temperature and remains consistent up to 700 MHz, but ferrimagnetic resonance frequency reduces from 900 to 700 MHz. For sintering temperature of 900 °C, almost matching value of permeability and permittivity equals to 5.5 and 5.3 respectively were obtained up to 700 MHz. The loss tangent are found to be of the order of 10−2 in the same frequency band. Matching values of er (~5.3) and μr (~5.5) are very effective in proper impedance matching of substrate material with free space. Analysis in High frequency structural simulator verifies that the synthesized magneto-dielectric material based antenna can miniaturize size (~65 %), lowers reflection losses (RL) by 15 %, higher −10 dB RL bandwidth (8–12 %) and higher voltage standing wave ratio bandwidth (9–13 %) at resonant frequency of 450 MHz. The observed matching values also result in higher gain and radiation efficiency. Hence, the excellent electromagnetic properties obtained in our investigation for the suitably sintered Ni0.5Zn0.3Co0.2In0.1Fe1.9O4 ferrite shows a lot of potential to be used as a substrate material in miniaturizing microstrip antenna for futuristic electronic devices.

Ultra‐wideband DRA integrated with narrow‐band slot antenna

A new ultra-wideband (UWB) antenna integrated with a narrow-band (NB) antenna has been designed and fabricated. The UWB antenna consists of a U-shaped dielectric resonator fed by a microstrip line. In addition, the proposed structure integrates an NB slot with the same polarisation. The electromagnetic analysis is carried out by using two commercial software tools. To validate the proposed concept, experimental measurements have also been performed. The measured results show that the dielectric resonator antenna (DRA) provides a wide bandwidth from 2.94 to 11.34 GHz (covering the UWB spectrum, 3.1-10.6 GHz) while the slot antenna provides a 2:1 voltage standing wave ratio bandwidth for 5.71-6.13 GHz. Moreover, the proposed design allows an efficient integration with very good isolation between the two ports (transmission coefficient S 21 <;-20 dB in the whole operating frequency band).

Multi-segment MPA with T-feed for multi-band wireless communication

A new antenna structure comprising multiple radiating microstrip patches, representing a digital figure of eight, proximity fed by a microstrip line is proposed. On a double-layered substrate of FR4, this antenna achieves multi-band functionality in the range 3.2–13.51 GHz which covers IEEE 802.11a standard and other wireless communication systems. It achieves multi-band functionality through the introduction of short connecting metallic strips which connect the different elements of the main radiating structure. The reflection coefficient spectra and the radiation patterns are suggestive of reconfigurability in frequency and pattern. Details of the antenna design and simulation results of the reflection coefficients, voltage standing wave ratio bandwidth, gain and the radiation pattern of the proposed antenna are presented. A prototype has been developed and successfully implemented.

A Small Broadband Omni-Directional Printed Antenna Comprising Symmetrically Arranged Trapezoid Elements

A small broadband omni-directional printed antenna comprising symmetrically arranged trapezoid elements is investigated for broadband Voltage Standing Wave Ratio (VSWR) and low center frequency characteristics. Two symmetrical trapezoid elements are printed on the bottom side of the substrate and are connected to a small ground plane printed on the same side over two strips. The trapezoid elements and the strips are excited in an electromagnetically coupled manner by the monopole element set between the trapezoid elements. Two resonance characteristics arise because the resonance part changes depending on the frequency, and a broad bandwidth becomes possible. The center frequency can be lowered by changing the shapes of the trapezoid elements. The monopole element length is a very important parameter for impedance matching. The space between the monopole element and the trapezoid elements is an important parameter for the optimization of two resonance characteristics. The proposed antenna is shown to achieve a VSWR bandwidth (≤2) of 28.9%, a low profile, and omni-directional pattern features. The measured and numerical results are in good agreement.

Bandwidth Enhancement of Antenna Arrays Utilizing Mutual Coupling between Antenna Elements

The mutual coupling effect between antenna elements on an array's bandwidth is investigated using scattering parameters instead of the mutual impedance. First, an approximate expression is derived for matched voltage standing wave ratio (VSWR) bandwidth of a tuned antenna, which reveals that the bandwidth is inversely proportional to the magnitude|Γ0'(ω0)|of the frequency derivative of the reflection coefficient. Next, considering linear antenna arrays with corporate feed as an example, closed-form expressions of the reflection coefficient are derived at the input port of the feeding network, which shows that the active reflection coefficient of an array is the linear superposition of elements' passive reflection coefficientS11and the mutual coupling coefficientS12from adjacent elements. The VSWR bandwidth expressions for an array imply that bandwidth enhancement of the overall array can be achieved when the element passive reflection coefficientS11and mutual couplingS12are cancelled, as well as the frequency derivativesS11'andS12'also cancel each other. Slot arrays and a two-element Vivaldi array are investigated to verify the validity of our theoretical analysis. Numerical and experimental results are presented to successfully demonstrate the bandwidth enhancement of antenna arrays utilizing mutual coupling effect.

A Wideband Low-Profile Antenna Composed of a Conducting Body of Revolution and a Shorted Parasitic Ring

An antenna composed of a conducting body of revolution (BOR) and a parasitic ring shorted to a finite-sized ground plate, designated as the BOR-SPR, is designed for realizing a low-profile base station antenna with a wideband voltage standing wave ratio (VSWR) characteristic. The design of the BOR-SPR starts with a center-fed patch antenna. To match the antenna input impedance to a 50-ohm feed line, as a first step, a slot is cut into the patch (this antenna is designated as Ant-I), and as a second step, shorted parasitic conducting pins are added to the periphery of Ant-I (this antenna is designated as Ant-II). Ant-II has a VSWR bandwidth of approximately 28%. Further increase in the VSWR bandwidth is achieved by replacing the inner feed region of Ant-II with a conducting BOR. It is found that this replacement, creating the BOR-SPR, yields an extremely wide VSWR bandwidth of approximately 147%, where the electrical antenna height at the lower edge frequency of the bandwidth is small: approximately 0.07 wavelength. It is also found that the radiation pattern of the BOR-SPR is similar to that of a monopole above a finite-sized ground plate. The beam direction thetas (measured from the direction normal to the surface of the BOR) varies between approximately 30deg and 60deg. The gain at thetas = 60deg is approximately 2 dBi near the lower edge frequency of the VSWR bandwidth and approximately 8 dBi near the upper edge frequency.

Limitations in Relating Quality Factor to Bandwidth in a Double Resonance Small Antenna

We examine the behavior of a matched electrically small antenna that exhibits two impedance resonances within its defined voltage standing wave ratio (VSWR) bandwidth. The exact quality factor (Q), computed indirectly from the antenna's input reactance and far field, is compared to twice the inverse of the matched half-power VSWR bandwidth (Q BW) and to an approximate quality factor (Qz) determined from the frequency derivative of the antenna's input impedance. The well-established approximate equalities Q ap Q BW ap Q z for antennas exhibiting an isolated single impedance resonance within their operating band are shown to become highly inaccurate for an electrically small antenna exhibiting two closely spaced impedance resonances.

Genetic Algorithm-based Design Optimisation of Aperture-coupled Rectangular Microstrip Antenna

The technique of feeding a microstrip antenna with a microstrip line through an aperture is gathering a lot of interest in communication and radar systems used for defence applications. This is due to the fact that this feeding technique has many adjustable parameters in the form of aperture length, width, and stub parameters. This paper presents a study on the effect of aperture dimensions and stub length on the voltage-standing wave ratio bandwidth of an aperturecoupled microstrip antenna. Without any additional matching network, optimal impedance matching of the antenna has been achieved using genetic algorithm. In the algorithm, each chromosome consists of three binary encoded genes, one for aperture length, second one for aperture width and the last one for stub length. Finally, the algorithm determines the parameters of the antenna that provides the minimum value of the average reflection coefficient. The investigation is made at different microwave frequency ranges and it extends up to Ku band. The results show that the percentage of fractional bandwidth improves for higher design frequencies and has a maximum of 13.2 per cent for centre frequency of 17.5 GHz. Experimental results are presented for a particular range of frequency and the accuracy of the analysis is briefly discussed.

Two Rectangular Loops Fed in Series for Broadband Circular Polarization and Impedance Matching

Two rectangular wire loops above an infinite ground plane are investigated for broadband circular polarization and impedance matching. Each rectangular loop is connected to each end of a short dipole fed by a coaxial cable through the ground plane. One gap on each loop is introduced to get circular polarization and the gap position controls the sense of circular polarization. The position of the gap, the length of the short dipole, the height of the loop above the ground plane and the shape of the rectangle are very important to get a good axial ratio (AR) and voltage standing-wave ratio (VSWR). The AR bandwidth (/spl les/3 dB) and the VSWR bandwidth (/spl les/2) are 18% and 22%, respectively. The measured and computed results are in good agreement.

Polarization-adjustable omnidirectional dipole array

The paper presents a unique omnidirectional three-element dipole array that can be adjusted to provide vertical, horizontal, or circular polarization for a variety of wireless applications. The 2:1 voltage standing wave ratio bandwidth of the antenna over all configurations is greater than 10%, but performance data is presented for the personal communication services (PCS) band (1850-1990 MHz).

New wide-band DC-block cymbal bandpass filter

A new low-loss dc-blocking parallel-cascaded bandpass filter is presented. The filter is much easier to use and fabricate, more compact, and simpler to design than the conventional end- or parallel-coupled line filters. The filter has a wide passband with a 2:1 voltage standing-wave ratio bandwidth of around 10% and an insertion loss of 0.5 dB at 10 GHz. Simulated results agree very well with experimental results.

Impedance characteristics of EMC triangular planar monopoles

The impedance characteristics of triangular planar monopoles, electromagnetically coupled with a probe-driven strip, are investigated experimentally. The 2:1 voltage standing wave ratio bandwidths of up to 50% are obtained.

Single-feed circularly polarized microstrip ring antenna and arrays

An analysis is presented for a microstrip-feed proximity-coupled ring antenna and a four-element array. Interactions between the embedded microstrip feed and the radiating element(s) are rigorously included. Results demonstrate that circular polarization of both senses can be achieved with a ring antenna with proper design of two inner stubs located at angles of /spl plusmn/45/spl deg/ with respect to the feedline. Theory and experiment demonstrate an axial ratio 3-dB bandwidth of 1% and the voltage standing wave ratio (VSWR) <2 bandwidth of 6.1%. The axial ratio bandwidth is typical for a microstrip antenna with perturbations, while the VSWR bandwidth is larger than for the circular or rectangular patch with perturbations. A mutual coupling study between two elements shows that the axial ratio is less than 2 dB for interelement spacing greater than 0.55/spl lambda//sub eff/, while the VSWR <2 for all spacings considered. A comparison between theory and experiment is provided for a 2/spl times/2 element array. The benefits of sequentially rotating the antenna elements in an array environment are presented. The axial ratio and VSWR bandwidths are both increased to 6.1% and 18% for a four-element array. A single-element antenna with two orthogonal feeds to provide both senses of polarization is demonstrated. The ring antenna is small (D//spl lambda//sub 0/=0.325), the substrate thickness is thin (H//spl lambda//sub 0//spl sim/0.035), and the microstrip feed produces a completely planar antenna system, which is compatible with microwave and millimeter integrated circuits (MICs), and monolithic microwave integrated circuits (MMICs).

A new quasi-Yagi antenna for planar active antenna arrays

In this paper, a novel broadband planar antenna based on the classic Yagi-Uda dipole antenna is presented, and its usefulness as an array antenna is explored. This "quasi-Yagi" antenna is realized on a high dielectric-constant substrate, and is completely compatible with microstrip circuitry and solid-state devices. This antenna achieves a measured 48% frequency bandwidth for voltage standing-wave ratio <2, better than a 12-dB front-to-back ratio, smaller than -15 dB cross polarization, and 3-5-dBi absolute gain. Mutual coupling of the antenna in an array environment is investigated. Finally, three simple arrays are presented, demonstrating the usefulness of the antenna as an array element. This novel antenna should find wide application in wireless communication systems, power combining, phased arrays, and active arrays, as well as millimeter-wave imaging arrays.