Microstrip Slot Antenna Research Articles

Development of a High SAR Conformal Antenna for Hyperthermia Tumors Treatment

A light weight, conformal, flexible, and clinically relevant hyperthermia applicator for the treatment of cancerous tumors has been developed. The applicator uses microwave hyperthermia for applying homogeneous thermal distribution with improved thermal dosimetry. The design utilizes a half wavelength meander-line to feed a microstrip slot antenna. It is capable of deeper penetration, has a high SAR and adequately matched input-impedance for various tissue loading. With a compact size of 11.0 cm×15.0 cm×0.47 cm without a back-shield and 11.0 cm×15.0 cm×0.98 cm with a back-shield, the applicator is capable to overcome many of the disadvantages of traditional hyperthermia applicators. The applicator has excellent SAR (point) with a measured value of 45 mm and exhibits a uniform E-field distribution, reduced surface and backfield irradiation and improved directional irradiation.

Research and Design of Magnetic Substrate Microstrip Antenna with Electromagnetic Band-Gap Structure

Based on the magnetic materials (JV-5) substrate, Double L-shaped slot microstrip antenna is designed. The bandwidth is over 2 times that of the normal substrate and a 40% reduction in size happens.. On this basis, the microstrip antenna with magnetic substrate EBG structure is designed and the EBG structure uses the corrosive effects of joint floor, namely getting periodic H-shaped and circular structures by the floor corrosion, and performing a simulation with HFSS14.0. The results show that the EBG structure of magnetic material having a prominent advantage of the miniaturization and bandwidth-broaden compared to a microstrip antenna with non-magnetic materials substrate, resulting in more than 10% relative bandwidth and a slight gain loss. To some degree, introducing EBG structure can reduce the size of the antenna and increase its bandwidth, and it also improve the gain and radiation characteristics of the antenna.Key words: EBG structure; magnetic material;Double L-shaped slot microstrip antenna; gain

H-U-E Shaped Slotted Microstrip Antenna for Bandwidth Enhancement

An H-U-E shaped slotted microstrip antenna with improved bandwidth is presented in this paper. The antenna resonates in the frequency range of (2.0–6.3) GHz with the center frequency of 4.2 GHz. The proposed antenna provides return loss approximately -30 dB. The antenna is fed with coaxial feeding yields an impedance bandwidth of 103.6% and VSWR of less than 1.07. The proposed antenna is simulated using Ansoft's HFSS software. The proposed H-U-E slotted microstrip antenna is suitable for wireless communications.

Design of compact reconfigurable ultra‐wideband slot antenna with switchable single/dual band notch functions

A compact reconfigurable microstrip slot antenna with switchable single and dual band notch functions for ultra-wideband (UWB) applications is presented in this study. In the proposed structure, an additional resonance is excited by etching two symmetrical notches on the feed-line and thereby a UWB characteristic is obtained. Then, by cutting two slots on the radiating patch and embedding two positive-intrinsic-negative (PIN) diodes along these slots, switchable single and dual band notch performances are added to the antenna performance. By changing the bias states of the PIN diodes, the antenna is capable of exhibiting four different performances of UWB spectrum coverage, UWB coverage with single rejection of the wireless local area network (WLAN) band, UWB coverage with single rejection of the WiMAX and C-band spectrum, and UWB coverage with dual band notch function at the WLAN, the WiMAX and the C-band frequencies. Good agreement between the simulated and the measured results is achieved at different performances of the antenna. The designed antenna has a small size of 20 × 20 mm 2 and the measured results reveal that the fabricated antenna has good radiation behaviour in the UWB frequency spectrum with switchable band notch functions at 3.15-3.85 and 5.43-6.1 GHz which can eliminate the UWB frequency band interference with the WiMAX, the C-band and the WLAN systems.

Band-notched UWB slot antenna

This article presents a new design of ultrawideband (UWB) microstrip slot antenna with band-notched function around 5–6 GHz to avoid any interference from the wireless local area network (WLAN) systems. The proposed antenna consists of a square radiating stub with a rotated C-ring slot, a feed-line and a slotted ground plane with an S-shaped parasitic structure inside an extra rectangular slot. By cutting a rectangular slot on top of the ground plane and also by embedding an S-shaped parasitic structure inside the slot, a new resonance at the higher frequencies is excited and hence much wider impedance bandwidth can be produced, which provides a wide usable fractional bandwidth of more than 135%. In the proposed design, to generate the WLAN band-stop property, the rotated C-ring slot was inserted at the radiating stub. Simulated and measured results are presented to validate the usefulness of the proposed antenna structure for UWB applications. The proposed monopole antenna configuration is simple, easy to fabricate and has a small size of 20 × 20 × 0.8 m3. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1744–1747, 2014

Estimation of radiation characteristics of different slotted microstrip antennas using a knowledge-based neural networks model

In this article, a common neural model incorporated with prior knowledge is suggested for estimating radiation characteristics i.e., resonance frequencies, gains, directivities, antenna efficiencies, and radiation efficiencies of four-slotted microstrip antennas with inserted air-gap for dual-frequency operation. By incorporating prior knowledge in the existing neural networks, the required numbers of training patterns are drastically reduced. Further, the proposed approach is capable for accurately estimating the radiation characteristics in extrapolation region too. The proposed neural approach is also validated with measured results. A very good agreement is achieved in simulated, estimated, and measured results. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:673-680, 2014.

Estimation of Different Performance Parameters of Slotted Microstrip Antennas with Air-Gap Using Neural Networks

Over the past decade, artificial neural networks have emerged as fast computational medium for predicting different performance parameters of microstrip antennas due to their learning and generalization features. This paper illustrates a neural network model for instantly predicting the resonance frequencies, gains, directivities, antenna efficiencies, and radiation efficiencies for dual-frequency operation of slotted microstrip antennas with air-gap. The proposed neural model is valid for any arbitrary slot-dimensions and inserted air-gap within their specified ranges. A prototype is fabricated using Roger’s substrate and its performance is measured for validation. A very good agreement is achieved in simulated, predicted, and measured results.

The design of linear and circular polarization for dual band microstrip slot antenna

AbstractThis paper presents a lightweight antenna for wireless communication systems. The proposed antenna has been designed to be a dual‐band and dual‐polarized antenna by using a right‐angled slot structure fed a by microstrip line. The designed antenna is composed of three right‐angled slot radiators on the ground plane. The first two radiators are right‐angled slots of similar scale which are added to generate circular polarization at 4.95 GHz, while the last one has been designed for linear polarization at 2.45 GHz. Furthermore, in order to achieve dual‐band operation and dual polarization with good matching, a special arrangement is proposed. The results of simulation and measurements such as return loss, axial ratio, and radiation patterns are shown at the resonant frequencies of 2.45 and 4.95 GHz. Details of the experimental results are presented and discussed. In addition, the presented antenna can operate and cover the applications of a wireless local area network (WLAN IEEE 802.11 a/b/g/j/n). © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

FREQUENCY RECONFIGURABLE MICROSTRIP PATCH-SLOT ANTENNA WITH DIRECTIONAL RADIATION PATTERN

In this paper, frequency reconfigurable slot-patch antenna with reflector at the back of an antenna is presented. The proposed antenna consists of a microstrip patch antenna and a microstrip slot antenna where the slot antenna is positioned at the ground plane underneath the patch. Three switches are placed in the slot. The antenna is capable to reconfigure up to six different frequency bands from 1.7 GHz to 3.5 GHz. The microstrip patch antenna produces three different frequency bands with directional radiation pattern while the microstrip slot antenna produces another three frequency bands with bidirectional radiation pattern. Due to the reflector placed at the back of the antenna, the radiation pattern is directional at all frequency bands. Simulated and measured results are used to demonstrate the performance of the antenna. The simulated and measured reflection coefficients and radiation patterns are presented and compared.

MUTUAL COUPLING REDUCTION OF A DUAL-FREQUENCY MICROSTRIP ANTENNA ARRAY BY USING U-SHAPED DGS AND INVERTED U-SHAPED MICROSTRIP RESONATOR

A compact U-shaped defective ground structure (DGS) and an inverted U-shaped resonator are introduced in order to reduce the mutual coupling (MC) between two slotted microstrip antennas at two difierent resonance frequencies. The proposed DGS and resonator have the same electrical length and both are placed in between two patch antennas, as a technique to suppress the occurrence of MC at two difierent frequency bands. The DGS and the resonator ofier stop bands at 2.45GHz and 4.5GHz respectively. Simulated results show a reduction in MC of 20dB at 2.45GHz band and 1dB at 4.5GHz band. We have developed experimental models that have proved this concept of MC reduction. Finally, the in∞uence of other parameters of the proposed antenna at the presence of the combination of DGS and resonator in the array system has been studied. Prototype antennas for difierent combinations of DGS and resonator and two-element array integrated with DGS and resonator have been fabricated, measured and the idea has been verifled. A good agreement is observed between measured and the simulated results.

Circularly Polarized Arrowhead-Shape Slotted Microstrip Antenna

A novel single-feed arrowhead-shape slotted microstrip antenna for circular polarization (CP) is proposed. To achieve CP radiation and antenna size reduction, an arrowhead-shaped slot is embedded in the first quadrant along the diagonal axes of a square patch. Thus, the structure is asymmetric, and good-quality CP performance can be achieved by adjusting the size of the slot. The antenna is simulated and practically fabricated. Measured results confirm the validity of this design and show a good agreement with simulated results. The antenna generates CP radiation at 911 MHz with an overall size of 87 × 87 × 4.572 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . The fabricated antenna shows an impedance bandwidth of 35.0 MHz (888.0-923.0 MHz) with 8.0 MHz (908.0-916.0 MHz) 3-dB axial-ratio bandwidth (ARBW).

STUDY OF SCAN BLINDNESS OF MICROSTRIP ARRAY BY USING DUMBBELL-SHAPED SPLIT-RING DGS

A compact dumbbell-shaped split-ring DGS is introduced between array elements of a sixteen-element microstrip array in order to reduce the mutual coupling between antenna elements and eliminate the scan blindness. The proposed DGS is inserted between the adjacent rectangle-shaped slotted microstrip antenna elements separated by 0.35λ, as a technique to suppress the radiation in the horizontal direction. Simulated results show that a reduction in mutual coupling of 36 dB is obtained between elements at the operation frequency of 2.45 GHz (WLAN band). The scan properties of microstrip array with and without DGS have been studied, and the result indicates that the scan blindness of the array has been well eliminated because of the effect of the DGS. We have developed experimental models that have proved the concept of scan blindness elimination. Finally, the influence of other antenna parameters at the presence of DGS in the array system has been studied. Prototype antennas of sixteen-element array with and without resonator have been fabricated, measured, and the idea has been verified. A good agreement is observed between measured and simulated results.

Reduction of Cross Polarization of Slotted Microstrip Antenna Array Using Spiral‐Ring Resonator

ABSTRACTDesign of a (2 × 2) E‐shaped microstrip patch antenna array integrated with spiral‐ring resonators (SRRs) is introduced for the reduction of cross‐polar (XP) radiation. The addition of SRRs in the array structure does not affect other characteristics of the array antenna. The array is designed to function in the 5.25 GHz that corresponds to IEEE 802.11a wireless LAN application. The characteristic analysis such as return loss (RL), bandwidth (BW), and radiation patterns of the antenna with and without SRRs have been investigated. The array offers a BW of 405 MHz (for RL &lt; −10 dB) covering frequencies ranges from 5.175 to 5.580 GHz and gain of 12.84 dBi has been achieved. The array has been studied both numerically and experimentally by introducing SRRs. The SRR geometry has been optimized for minimum XP radiation. The XP radiation has been reduced by 7 dB with two SSRs and 12.0 dB by four SRRs of similar geometry, placed in between the patch elements of the array structure. Prototype antennas with and without SRRs have been fabricated tested and a remarkable agreement is obtained between the measured and the simulated results. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2083–2088, 2013

Back Radiation Suppression in Modified Aperture Coupled Microstrip Antenna by using patches under the substrate

A microstrip slot antenna for C Band has been proposed with compact structure and suppressed back radiation. In this paper, the feeding technique used is aperture coupling with a modification that patches and the feed line are positioned below the substrate and the slot is etched above the substrate. The position of the patches along the slot axis is kept at the negative peak of the standing wave distributions to generate the voltage null on the slot line so as to have a 180º phase shift in the centre of the patch hence achieving better front to back ratio. Also the gain of 6.774dB is achieved in this design. The results are validated by simulation measurements.

Planar Microstrip Slot Antenna for S & C band Wireless Applications

In this paper, compact planar microstrip antennas comprising of broad slots for enhancing various antenna parameters are discussed and presented. The proposed microstrip slot antennas achieved a compactness of maximum 58 % with a peak gain of 7.58 dB. These antennas can be operated for S band applications such as WiMax, operating in the frequency range of 3.3 – 3.6 GHz, RADAR, WLAN, fixed satellite services and maritime mobile services etc. covering 2 – 6 GHz frequency range. The antennas can be used as a compact antenna system where limited size is a foremost requirement. Results also show the satisfactory performance with the dual band frequency characteristics. Details of the antenna design structure, results of return loss (RL), impedance bandwidth and radiation pattern with co-cross polarization are also given

Slotted Microstrip Antennas for Circular Polarization with Compact Size

Circularly polarized diagonally symmetric slotted microstrip-patch antennas are proposed with compact size. The compact circularly polarized (CP) diagonally symmetric slotted microstrip-patch (DSSMP) antenna design rules are also summarized. Circularly polarized radiation can be achieved using any arbitrarily shaped slots in diagonal directions on the square microstrip-patch antenna. Different shapes for the slots are studied and compared, based on the fixed overall volume of the antenna for circularly polarized diagonally symmetric slotted microstrip-patch antennas. The cross-shaped-slot diagonally symmetric slotted microstrip-patch antenna is compact when compared with the circular-, square-, and circular-ring-shaped diagonally symmetric slotted microstrip-patch antennas. A measured 3 dB axial-ratio (AR) bandwidth of around 0.7% (6.0 MHz) with 2.0% (18.0 MHz) impedance bandwidth was achieved. The measured boresight gain was more than 3.3 dBic over the operating band, while the overall antenna size was 0.272λ0 × 0.272λ0 × 0.0138λ0 at 0.905 GHz.

Frequency Reconfigurable Microstrip Loop Antenna Covering LTE Bands With MIMO Implementation and Wideband Microstrip Slot Antenna all for Portable Wireless DTV Media Player

A microstrip slot antenna covering Digital TV (DTV) and frequency reconfigurable microstrip printed loop antenna operating at LTE bands 3 (1.8 GHz) and 7 (2.6 GHz) with multiple-input-multiple-output (MIMO) implementation are designed which can find applications in portable wireless DTV media players. The DTV antenna is matched from 496-862 MHz and LTE bands 3 and 7 from 1710-1880 MHz and 2500-2700 MHz, respectively, all considering S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> = -6 dB matching criterion. Further, the LTE bands antennas are frequency reconfigurable antennas and its MIMO implementation shows an envelope correlation (EC) below 0.22 for both the LTE bands. Prototype antennas were fabricated and experimental verification was performed.

Multiband MIMO Antenna System with Parasitic Elements for WLAN and WiMAX Application

A new microstrip slot antenna with parasitic elements has been presented in this paper. The proposed antenna is composed of a microstrip feed line, a ground plane on which some simple slots are etched, and parasitic elements. Simulation results show that the antenna structure allows for the independent adjustment of each frequency. A two-element array configuration of this antenna for MIMO application is investigated as well. For comparison between simulation and measurement result both single and array configurations have been fabricated. The measurement result exhibits good radiation performance in terms of return loss, low mutual coupling, and compactness.

Comparison on the Reception Property of Gunn Mounted ASRA and AMPA

A Gunn mounted active microstrip patch antenna (AMPA) and active microstrip slot antenna (ASRA) has been investigated for the reception of FM microwave signal. Current well/valley phenomenon has been successfully utilized to demodulate the modulation information. Reception poperty of the both antennas are studied in multi-channel environment. Because of its simple circuit configuration and similarity in transmitter and receiver architecture, active patch antenna as demonstrated is well suited for commercial and military application as a two-way microwave communication system. A comparative study on the role of AMPA and ASRA as a receiver shows that ASRA do better performances than AMPA. In case of ASRA the modulating signal are demodulated without any distortion. ASRA also has large locking range (29 MHz) compare to AMPA (5 MHz). So the ASRA has broad band tuning capabilities than AMPA. With ASRA configuration demodulation bandwidth in excess of 14 MHz is realizable which can successfully accommodate a large number of voice or data channels.

Novel F-Shaped Quad-Band Printed Slot Antenna for WLAN and WiMAX MIMO Systems

A novel F-shaped microstrip slot antenna for WLAN and WiMAX multiple-input-multiple-output (MIMO) systems is presented. The proposed antenna structure consists of both open-ended and short-ended slots connected by a metal “via” to a microstrip line. The open-ended slot is exploited to obtain resonant mode at 2.4 GHz, and three short-ended slots are aimed to obtain resonant modes at 3.5, 5.2, and 5.8 GHz, whose center frequencies can be adjust by the slot lengths. The parametric studies show that the center frequencies are independent of each other. A four-element array configuration of the proposed antenna for MIMO applications is also studied. The simulation and measurement results of reflection coefficient, mutual coupling, and radiation pattern are presented, which attest to the applicability of antenna.