Enhanced Impedance Bandwidth Research Articles

PMC‐Based Waveguide‐Fed Slot Array

Perfect magnetic conductors (PMCs) can help in the enhancement of antenna impedance bandwidth using their capability of reflecting the incident waves without phase reversal. The purpose of this paper is to show the advantages of using a perfect magnetic conductor in antenna engineering. The goal is to use it in waveguide‐fed slot array antennas, increasing both the antenna impedance and radiation bandwidths. To this aim, a PMC‐based rectangular waveguide composed of longitudinal slots is convenient. The impedance of the proposed array structure is calculated analytically. To compare analytical results with the simulation results, PEC‐ and PMC‐based waveguide‐fed slot arrays are designed and simulated in a certain frequency band. The simulation results are in good agreement with the theoretical predictions.

PMC-Based Waveguide-Fed Slot Array

Perfect magnetic conductors (PMCs) can help in the enhancement of antenna impedance bandwidth using their capability of reflecting the incident waves without phase reversal. The purpose of this paper is to show the advantages of using a perfect magnetic conductor in antenna engineering. The goal is to use it in waveguide-fed slot array antennas, increasing both the antenna impedance and radiation bandwidths. To this aim, a PMC-based rectangular waveguide composed of longitudinal slots is convenient. The impedance of the proposed array structure is calculated analytically. To compare analytical results with the simulation results, PEC- and PMC-based waveguide-fed slot arrays are designed and simulated in a certain frequency band. The simulation results are in good agreement with the theoretical predictions.

Wideband Phase-Reversal Antenna Using a Novel Bandwidth Enhancement Technique

A novel bandwidth enhancement technique for phase-reversal Franklin-type antennas is proposed. Impedance bandwidth enhancement is achieved by combining several coupled modes of the antenna structure through periodic loading provided by radiating crossover dipoles. This technique is explained by the theory of periodically loaded transmission lines. Radiation pattern bandwidth enhancement is achieved by exciting the antenna in its center so as to suppress beam squinting by superposing the tilted beams of two resulting sub-arrays on either side of the feed. An offset parallel stripline (OPS) phase-reversal antenna using these bandwidth enhancement techniques is demonstrated theoretically and experimentally at 35 GHz. The antenna is printed on a thin substrate suspended over a micro-machined conductor-backed cavity for unidirectional radiation. The overall fractional bandwidth of the antenna is increased from 3% to over 11% compared to the conventional design and the antenna efficiency exceeds 80%.

Bandwidth enhancement of a coplanar waveguide-fed asymmetrical slot antenna with a rectangular patch

A coplanar waveguide-fed asymmetrical slot antenna with a rectangular patch for bandwidth enhancement is demonstrated.By attaching a rectangular patch to the monopole radiating element, a good performance of bandwidth enhancement for the antenna is achieved. From simulational and experimental results, the enhanced impedance bandwidth of the proposed antenna, defined by −10 dB return loss, can reach 13.1 GHz, from 2.4 to 15.5 GHz, or about 146% with the center frequency 8.95 GHz, which makes it an excellent candidate for the ultra wideband (UWB, 3.1–10.6 GHz) applications. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2259–2261, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25476

Ultra‐wideband microstrip antenna with enhanced impedance bandwidth

AbstractThis article presents a novel ultra‐wideband (UWB) microstrip‐fed planar monopole antenna composed of a rectangular patch and a ground‐plane π‐shape slot structure. Impedance bandwidth of the proposed antenna is ∼147% over an UWB frequency range between 3 and 19.7 GHz satisfying FCC's requirements for an antenna by a factor in excess of twofold. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:870–873, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25072

DUAL BAND-NOTCHED DESIGN OF RECTANGULAR MONOPOLE ANTENNA FOR UWB APPLICATIONS

An ultra wideband (UWB) coplanar waveguide (CPW) fed rectangular monopole antenna, which is of band notched characteristic for Wireless Local Area Network (WLAN), Worldwide inter-operability for Microwave Access (WiMAX) and the C-band satellite communications, is proposed, fabricated and measured. In order to obtain the desired dual band rejections, a piece of pentagonal slotline and a pair of inverted L-shaped stubs are loaded on the CPW fed rectangular monopole antenna of enhanced impedance bandwidth. The antenna is printed on the FR4 substrate of 40mm (width) £ 41mm (length) £ 0.5mm (thickness), and is optimized by ANSOFT HFSS. A prototype is fabricated according to the optimized parameters values, and the antenna characteristics are measured. The results show that the antenna is of UWB characteristic and exhibits band rejection of 3.2{4.25GHz and 5.1{6.15GHz, which covers WLAN, WiMAX, and C-band satellite communications.

Enhanced bandwidth of low-profile sleeve monopole antenna for indoor base station application

The design and enhanced bandwidth performance of a monopole antenna with a simple sleeve structure for indoor base station application is presented. Besides a top-loading circular patch shorted to the ground plane through four shorting probes for a low profile, the circular sleeve structure to effectively improve the matching condition of the upper operating frequency edge can be used for bandwidth enhancement. An enhanced impedance bandwidth of about 112% ranging from 750 to 2660 MHz (VSWR≤2) is achieved, and a monopole-like conical radiation pattern is also produced. With this low profile and the widened bandwidth characteristic, it is very suitable for indoor base station applications such as GSM900, DCS1800, PCS1900, UMTS, IMT2000, Wibro, WiMAX2350, and WLAN (IEEE802.11b).

A wideband linear U-slot microstrip patch antenna array for wireless application

Microstrip antennas suffer an inherent disadvantage of narrow impedance bandwidth, normally within 5%. In this article, a single layer linear U-slot microstrip patch antenna array is designed, fabricated and characterised. The measured results agree well with the simulated, showing an enhanced impedance bandwidth (voltage standing wave ratio < 2) of 10.6%, ranging from 5.35 to 5.95 GHz, on an FR4 substrate. The antenna array has high efficiency and gain. Only a pair of sidelobes appear in the E plane radiation pattern. The reported linear array design can provide a method of expanding to 4 × N antenna array for satellite to ground communication operating at C band.

Design of Compact Broadband Microstrip Antennas Using Coplanar Coupled Resonators

In this paper, we present novel configurations of compact and broadband coupled microstrip antennas (MSAs). Bandwidths of the proposed antennas are 5.4–6.1 times greater than the corresponding conventional MSAs. A simple and straightforward incorporated design procedure provides an impedance bandwidth enhancement without increasing the antenna size. These antennas consist of a driven patch and another short-circuited parasitic patch. The proposed antennas are numerically investigated using Finite Element Method (FEM) based software (HFSS). Experimental results are also presented and comparison between simulations and measurements are provided. Simulations and measurements demonstrate a good agreement.

DUAL-BAND AND WIDEBAND DESIGN OF A PRINTED DIPOLE ANTENNA INTEGRATED WITH DUAL-BAND BALUN

A dual-band printed dipole antenna with integrated balun feed is given in this paper. First, the fork-shaped slot is etched on the arms of the printed dipole antenna to achieve the dual-band operation with resonances at WLAN bands. The radiating element without balun is optimized and operates at 2.4 GHz (2180–2750MHz) and 5.2GHz (5040 MHz–5480MHz) where return loss is less than −10 dB. In order to get a larger bandwidth, a modified Marchand balun is introduced for dual-band operation, which can provide two resonances in each band to enhance impedance bandwidth. By co-designing the radiating element with the dual-band balun, an antenna covering 2150–2750 MHz and 5050–6230 MHz bands has been achieved. The design equations for modified balun have been presented and agreement between calculation and measurement is good.

Ultrawideband Suspended Plate Antenna With Enhanced Impedance and Radiation Performance

We describe an ultrawideband (UWB) suspended plate antenna (SPA) with enhanced impedance and radiation performance. This antenna consists of two layers. The bottom plate is suspended above a ground plane and fed by a tapered down feeding strip. The top layer consists of four identical radiating plates, each connected to the bottom plate by a vertical strip. The design is optimized numerically and validated experimentally. The measured results show that the antenna achieves an enhanced impedance bandwidth of 72.7% (2.8-6.0 GHz) for VSWR les 2 with stable radiation performance in terms of gain from 8.0-9.9 dBi, direction of maximum radiation, and high copolarization-to-cross-polarization ratio of ges 12 dB across the lower UWB band of 3.1-4.8 GHz.

An enhanced bandwidth design technique for Peano fractal loaded monopole antenna

AbstractA new technique for Peano fractal loaded monopole antenna to enhance impedance bandwidth by loading shorting pins is presented. Simulated and measured data show that relative impedance bandwidths of the proposed order 1 and order 2 antennas achieve 23 and 28% for VSWR less than 2 in L‐band, which are enhanced 90 and 75% than those of conventional ones, respectively, while the profile and radiation patterns change little. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2045–2048, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23583

New bandwidth enhancement and multiresonance technique for microstrip patch antenna

AbstractThe quality factor, bandwidth, and efficiency are antenna's figures of merit and these are interrelated. There is no typical method that gives full freedom to optimize these independently. Here we proposed a novel and new method to optimize bandwidth with respect to radiation quality factor Qr. Slicing a substrate into two thin layers substrate, an impedance bandwidth of 12% is achieved while reducing the volume by 44.5%. The technique proposed shows that instead of single thick substrate, if two thin substrates are used, an enhancement of impedance bandwidth takes place while maintaining high antenna gain and radiation efficiency. This is a new and novel technique for bandwidth enhancement in microstrip patch antenna and is quite different from stacked antenna. In this article, we sliced a substrate into two thin substrates each of 1‐mm thick to achieve a bandwidth of 12% and radiation efficiency of 80.5549 with an overall volume reduction of 44.5%. While a single substrate of thickness 2.5 mm which is more than the total thickness of the discussed structure gives only 5% bandwidth for same antenna dimensions. The proposed structure will find potential application in MIMO antenna system due to its volume reduction and other enhanced features. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1162–1165, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23323

BIDIRECTIONAL ULTRA-WIDEBAND ANTENNA USING RECTANGULAR RING FED BY STEPPED MONOPOLE

This paper presents an ultra-wideband rectangular ring fed by stepped monopole antenna. The initial parameters of rectangular ring are first considered to obtain the bidirectional pattern with the desired resonant frequency. Subsequently, the parameters of stepped monopole for enhancing impedance bandwidth are investigated. To study the impedance and radiation behaviors, the simulations of the proposed antenna have been carried out. It is found that this antenna offers a bidirectional beam with the impedance bandwidth (return loss lower than −10 dB) covered the frequency range from 3.1 to 10.6 GHz. At the desired direction along this frequency band, the gain of 2.33-5.21 dBi is achieved. Furthermore, the prototype antenna was fabricated and measured to verify the simulated results. Obviously, the simulation and measurement are reasonably in good agreement.

Multi-criteria design methodology of a dielectric resonator antenna with jumping genes evolutionary algorithm

A novel evolutionary computing algorithm, jumping genes evolutionary algorithm (JGEA) is used for designing a dielectric resonator antenna with multiple parasitic strips. This scheme provides an effective methodology for the antenna design, searching for the necessary parameters to achieve the optimal performance. The obtained non-dominated solutions for the antenna configurations have been used to select and determine the appropriate impedance bandwidth and radiation pattern. In the LP DRA optimization, the impedance bandwidth of 21% has been achieved. In the CP DRA optimization, the antenna can be designed to achieve the operation frequency ranged from 3 to 4.2 GHz. The results show enhancement of impedance bandwidth and the CP operation frequency range comparing with the original designs.

Dual‐band monopole antenna excited by a capacitive coupling feed for WLAN applications

AbstractA printed dual‐band T‐shaped monopole antenna with a shorted strip fed by a coupling microstrip line for wireless communication in the wireless local‐area network (WLAN) band is studied. The proposed antenna can provide two separate impedance bandwidths of 101 MHz (about 4.1% centered at 2.45 GHz) and 1490 MHz (about 27% centered at 5.5 GHz), making it easier to cover the required bandwidths for WLAN operation in the 2.45 GHz band (about 3.4% bandwidth required) and 5.2/5.8 GHz bands (about 13% bandwidth required). We can easily find the enhancement of impedance bandwidth by using capacitive coupling feed. Details of the proposed antenna design and experimental results are presented and discussed. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1135–1138, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22380

Polarisation-diversity antenna for TPMS application

A low profile antenna, with polarisation diversity, for operation in a tyre pressure monitoring system (TPMS), is investigated. By combining the signals received from the two ports in phase or 180° out of phase, the antenna can operate at two different modes: a top-loaded monopole antenna and a planar dipole antenna located very close to a conducting plane (about 0.028 λ). Two significant techniques are used to enhance impedance bandwidth and to reduce antenna length. A prototype is implemented and the results obtained are given.

Characteristic of narrow‐slot antennas on periodic ground planes

AbstractThis article presents the experimental results of two narrow slot antennas, a line‐slot antenna, and a square‐slot antenna with microstrip feeding, for wide‐band operation. By selecting certain elements resembled in the slot shape, we implemented two designs with a ground plane of periodical surface, and obtained significant enhancements in the antenna bandwidth for both designs. The impedance bandwidth enhancement was as many as seven times and four times of conventional line‐ and square narrow slot antennas, respectively. Details of the experimental results are presented and discussed. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 138–141, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22087

Analysis of an E‐shaped patch antenna

AbstractThis paper presents the theoretical and simulation investigations of an E‐shaped patch antenna applicable in modern mobile communications. It shows marked improvement in the bandwidth when compared with rectangular patch antenna with acceptable radiation pattern. Further, the bandwidth is optimized with respect to notch length, width, and position. Typically, the antenna shows an enhanced impedance bandwidth of 32.5%. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 4–7, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22024

On Impedance Bandwidth of Resonant Patch Antennas Implemented Using Structures With Engineered Dispersion

We consider resonant patch antennas, implemented using loaded transmission-line networks and other exotic structures having engineered dispersion. An analytical expression is derived for the ratio of radiation quality factors of such antennas and conventional patch antennas loaded with (reference) dielectrics. In the ideal case this ratio depends only on the propagation constant and wave impedance of the structure under test, and it can be conveniently used to study what kind of dispersion leads to improved impedance bandwidth. We illustrate the effect of dispersion by implementing a resonant patch antenna using a periodic network of LC elements. The analytical results predicting enhanced impedance bandwidth compared to the reference results are validated using a commercial circuit simulator. Discussion is conducted on the practical limitations for the use of the proposed expression.