Microstrip Antennas

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Review of Some Investigations on
Rectangular Microstrip Antennas with
Embedded Slots

Review of Some Investigations on Rectangular Microstrip Antennas with Embedded Slots

loads between the patch and the ground plane, such as pins and varactor diodes, adaptive elements with variable resonant frequency, impedance, polarization, and pattern can be designed. Major operational disadvantages of microstrip antennas are their low efficiency, low power, high Q (sometimes in excess of 100), poor polarization purity, poor scan performance, spurious feed radiation and very narrow frequency bandwidth, which is typically only a fraction of a percent or at most a few percent. However, there are methods, such as increasing the height of the substrate, that can be used to extend the efficiency (to as large as 90 percent if surface waves are not included) and bandwidth (up to about 35%).However, as the height increases, surface waves are introduced which usually are not desirable because they extract power from the total available for direct radiation (space waves). The surface waves travel within the substrate and they are scattered at bends and surface discontinuities, such as the truncation of the dielectric and ground plane, and degrade the antenna pattern and polarization characteristics. Surface waves can be eliminated, while maintaining large bandwidths, by using cavities. Other methods, of microstrip elements can also be used to increase the bandwidth. In addition, microstrip antennas also exhibit large electromagnetic signatures at certain frequencies outside the operating
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An Approach to Equivalent Circuit Modeling of Rectangular Microstrip Antennas

An Approach to Equivalent Circuit Modeling of Rectangular Microstrip Antennas

The narrowband equivalent circuit of a rectangular microstrip patch antenna (RMPA) has been related to the physical dimensions of the antenna [10]. Kajfez proposed a systematic approach to calculate the equivalent circuit of double resonant microstrip antennas [11]. Later, Kim devised a procedure to calculate the wideband equivalent circuit of broadband antennas [12]. However, the singular value decomposition technique utilized in [12] has failed to converge to physically realizable circuits in case of rectangular and wideband E-shaped microstrip antennas. In this paper, the topology of the equivalent circuit is fixed and thus, this issue has been resolved in case of rectangular and wideband E-shaped microstrip antennas.
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Review of Circularly Polarized Microstrip Antennas for RFID Application

Review of Circularly Polarized Microstrip Antennas for RFID Application

RFID is a technology that provides wireless identification and tracking capabilities. In recent years, RFID technology has been rapidly developed and applied to many service industries, distribution logistics, manufacturing companies. In an ultra-high-frequency (UHF) RFID system, the reader emits signals through reader antennas. An RFID tag, located at the client consists of an antenna and an application-specific integrated circuit (ASIC). The tag is activated and interrogated for its content information by the reader. The querying signal from the reader must have enough power to activate the tag ASIC to perform data processing, and transmit back a modulated string over a required reading distance. Since the RFID tags are always arbitrarily oriented in practical usage and the tag antennas are normally linearly polarized, circularly polarized (CP) reader antennas have been used in UHF RFID systems for ensuring the reliability of communications between readers and tags [1,2].Circularly polarized microstrip antennas can reduce the loss caused by the multipath effects between the reader and the tag antenna. Circularly polarized (CP) radiation is advantageous because it works independently of the orientation of the transmitter and receiver antennas in wireless communication systems.
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Broadband Microstrip Antennas Using Coplanar Feed-Line

Broadband Microstrip Antennas Using Coplanar Feed-Line

Abstract—This paper proposes two novel broadband microstrip antennas using coplanar feed-line. By feeding the patch with a suitable shape of the coplanar line in the slot of the patch, the broadband character is achieved. Compared with the antenna fed by a U-shaped feed-line, the antenna with L-shaped feed-line not only has wider bandwidth but also achieves the circular polarization character. The measured bandwidths of 25% and 34% are achieved, and both of the antennas have good radiation characteristics in the work band.

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Left Handed Material Based Directive Microstrip Antennas

Left Handed Material Based Directive Microstrip Antennas

engineering applications related to the important area of wireless communications, and how LHM can have a strong impact on the performance of microstrip antennas [5]. Design then tunable narrowband antennas are the best solution for it. Tunability is always done in the same operating band of frequency. Another alternative for multiband antenna is reconfigurable antennas. The concept of reconfigurability means changing the operating band of frequency. It reduces the complexity as well increase the capability of the system. Frequency- reconfigurable antennas are those antennas in which operating frequency can be classified into two categories: Switched and continuous, in the switched frequency – tunable antennas, the centre frequency is changed in discrete steps whereas the continuous frequency- tunable antennas allow continuous change in the centre frequency. Both types of antennas in general share a common theory of operation and reconfiguration mechanism – the main difference being the extent of the effective length change that enable operation over different frequency bands and the switching mechanism used to achieve these changes.
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Artificial Intelligence in the Estimation of Patch Dimensions of Rectangular Microstrip Antennas

Artificial Intelligence in the Estimation of Patch Dimensions of Rectangular Microstrip Antennas

Microstrip antennas are used in a wide range of mobile communication applications which demands multi band and/or wideband frequency operations, high power gain omni directional radiations patterns etc. Therefore design of printed antennas to meet the requirements of multiple operational services becomes a difficult task. This war- rants in the very high accuracy of the calculation of various design parameters of microstrip patch antennas. Patch dimensions of a rectangular microstrip antenna is a vital parameter in deciding the performance and the utility of an antenna. In the present work, microstrip line feeding is taken as a preferred method of feeding the input power to the antenna. The calculation of exact patch dimensions of rectangular microstrip patch antenna becomes ex- tremely important where the antenna size is drastically small. A number of papers have been appeared on the calculation of patch dimension of microstrip antennas
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Three Optimized Omnidirectional Microstrip Antennas (OMA) for WLAN Applications

Three Optimized Omnidirectional Microstrip Antennas (OMA) for WLAN Applications

Many wireless application channels using 802.11b (2.45 GHz), 802.11a (5.2 GHz) and WiMAX protocols. These systems need antennas with omnidirectional radiation pattern in the azimuth plane and narrow beam width radiation pattern in the elevation plane for large service area coverage. The microstrip antennas are good candidates for these applications due to their small size, easy installation and low cost. For WLAN applications and WiMAX systems, several design methods for omnidirectional antennas have been developed in [1–5]. The collinear dipole array (COA) is a well-known high-gain dipole antenna introduced in [6] based on Franklin idea. This antenna includes U-shaped wire sections to keep the current feeding of the longitudinal radiating wire antenna in-phase. The omnidirectional coaxial collinear (COCO) antennas are composed of series half wavelength coaxial cable sections where their inner and outer cable conductors are transposed at each section [7]. Based on the COCO antenna concept, a planar omnidirectional microstrip antenna (OMA) has been proposed in [8–10]. Also, a number of design approaches have been proposed in the literatures for multi-band or wide-band omnidirectional antennas. A dual-band OMA has been proposed in [11]. In this antenna, the higher frequency radiation with low-pass filtering attribute is placed near the antenna feed and a relatively lower frequency radiating array at the end which increases the antenna dimension significantly. In [12], an omnidirectional broad-bandwidth microstrip array antenna has been proposed for WiMAX applications suitable for WLAN operation at 5.2 GHz (5.150–5.350 GHz) and 5.8 GHz (5.725–5.875 GHz) bands comprising two back-to-back folded dipoles printed on a dielectric substrate. In [13], a novel shunt- fed triband printed two-element collinear dipole array antenna has been presented for required bands of GSM850 (824–894 MHz), DCS (1710–1880 MHz), and PCS (1850–1990 MHz). Moreover, some efforts have been made in the literatures to design a circular polarization and dual-polarization omnidirectional antenna. In [14] a compact omnidirectional antenna with circular polarization has been presented for
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Support Vector Characterisation of the Microstrip Antennas Based on Measurements

Support Vector Characterisation of the Microstrip Antennas Based on Measurements

Two kinds of theoretical approaches can be exploited in characterizing the resonant frequency, bandwidth, input impedance of the patch antennas. The first group starts from initial physical assumptions, which generally offers simple and analytical formulas, well suited for a physical understanding of phenomena and for future antenna computer-aided design (CAD). These methods are known as transmission-line models and cavity models. However, these methods do not consider rigorously the effects of surface waves. The second approach is based on an electromagnetic boundary problem, which leads to an expression as an integral equation, using proper Green functions, either in the spectral domain, or directly in the space domain, using moment methods. Without any initial assumption, the choice of test functions and the path integration appear to be more critical during the final, numerical solution. Exact mathematical formulations in the second group rigorous methods involve extensive numerical procedures, resulting in round-off errors, and may also need final experimental adjustments to the theoretical results. They are also time consuming and not easily included in a CAD system. However, the theoretical values obtained by using both these two theoretical methods are also not in very good agreement with the experimental results of both electrically thin and thick rectangular microstrip antennas [3–5]. For these reasons, some numerical/experimental methods for the analysis of microstrip antennas is worked out [6– 9]. In this work an advanced nonlinear learning machine, “Support Vector Machine (SVM)” is employed in analyzing the rectangular patch antenna, which enable to generalize ‘discrete’ data into the ‘continuous’ domain. In particular, SVMs are based on a judicious and rigorous mathematics combining the generalization and optimization theories together and verified to be computationally very efficient (the so-called Vapnik-Chervonenkis theory [10, 11]). This learning machine has found many fruitful applications in science and engineering, especially the typical applications in signal processing, modeling of microwave devices and antennas are given in [12–20].
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Review on CPW – Fed Microstrip Antennas

Review on CPW – Fed Microstrip Antennas

Fig.10 Configuration of E shaped microstrip antenna A common rectangular patch antenna can be represented by means of the equivalent circuit. The resonant frequency is determined by L ₁ C ₁ . At the resonant frequency, the impedance of the series LC circuit is zero, and the antenna input impedance is given by resistance R. By varying the feed location, the value of resistance R may be controlled such that it matches the characteristic impedance of the coaxial feed. When a pair of slots is incorporated, the equivalent circuit can be modified. The second resonant frequency is determined by L₂C₂. Analysis of the antenna input impedance shows the three-dimensional perspective view of the printed meander lines. The width of metal patterns from 0.3 to 1.0 mm and the diameter of via holes is 0.5 mm. A rectangular patch and a few E-shaped microstrip antennas are fabricated. Measurement results are obtained to compare with simulation results [5].
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Design of Low Cost Microstrip Antennas for Wireless Sensor Networks

Design of Low Cost Microstrip Antennas for Wireless Sensor Networks

Microstrip antennas are frequently used in today's wireless communication systems because of their low profile, light weight and low production cost which widely have been researched and developed in the recent twenty years (Sleman and R. Moeller, 2008; Hac, A., 2003; Malan, D., et al., Wong, K.-L., et al., 2003). Nevertheless, there are several disadvantages of microstrip antennas. Narrow operation bandwidth is the main disadvantage. The bandwidth of the basic patch antenna is usually 1 – 3%. The bandwidth of the antenna depends on the patch shape, dielectric constant, the thickness of the substrate and the resonant frequency (CHU, L.J., 2005).
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Design, Fabrication and Comparison Of Microstrip Antennas for L-Band Applications

Design, Fabrication and Comparison Of Microstrip Antennas for L-Band Applications

A Microstrip antenna consists of conducting patch on a ground plane separated by dielectric substrate. Microstrip antennas have extensive applications as transceivers in wireless sensor networks (WSN). The development of wireless sensor networks was motivated by military applications such as battlefield surveillance; today such networks are used in many industrial and consumer applications, such as industrial process monitoring and control, machine health monitoring, environment and habitat monitoring, healthcare applications, home automation and traffic control.
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Shorted Circular Microstrip Antennas for 50 Ω Microstrip Line Feed with Very Low Cross Polarization

Shorted Circular Microstrip Antennas for 50 Ω Microstrip Line Feed with Very Low Cross Polarization

In modern days, the concepts of creating compact and impedance-agile microstrip antennas (MSAs) has attracted increasing attention due to miniaturization and ease of integration with microwave circuits and devices [1–8, 10–12, 14–16]. Compact MSAs have been realized by the simple method of loading the patch by either shorting post (pin) or shorting plate [1–8]. Shorting post is connected between the patch and ground plane, which helps to perturb the surface current distribution on the patch. It also forces the electric field to become zero at that point, thereby modifies various modes of the patch [2, 4]. Shorting posts along the zero field line of fundamental mode of the patch converts half wave length resonator into quarter wavelength, which help to realize compact MSA. Compact and shorted configurations of rectangular, circular and triangular antennas with the shorting post technique have been reported in [2, 4]. Besides realizing compactness, the shorting technique has also been used to obtain dual-frequency response [5], tunability [9], impedance matching [10–12, 14–16], etc. Recently, various configurations of compact and broadband MSAs have been reported using shorting techniques [6– 8]. Direct integration of MSA elements with coplanar 50 Ω microstrip (MS)-line feed on the same plane is highly demanded in on-chip platform, to make a compact electronic system.
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Designing and modeling of compact 
		microstrip antennas using new nanocomposite materials

Designing and modeling of compact microstrip antennas using new nanocomposite materials

This paper is the first applied study on the designing and modeling of compact microstrip antennas using new polymer nanocomposite magneto materials. New materials used in designing and modeling process of compact microstrip antenna are iron oxide polymer nanocomposite magnetic materials. Polymeric nanoparticles materials are created by iron oxide nanocomposite materials based on polydimethylsiloxane (PDMS). Nowadays, several researchers have been proposed magneto materials for minimizing and increasing the antennas bandwidth. Nevertheless, properties such as high loss and decreasing control in magnetic properties prevent the optimal performance of antennas. In addition, the incompatibility and high complexity prevents integration of conventional magnetic materials with antennas and standard fabrication processes at printed circuit boards and wafer levels. Additionally, low losses in magnetic nanoparticles accompany by the ease of integration of polymer nanocomposites in standard fabrication processes, suggests solutions to resolve any of the complications and concerns. So the present paper aim was designing and modeling of multilayer compact microstrip antenna using new polymer nanocomposite materials. In this paper, one multilayer antenna was created using new polymer nanocomposite materials based on PDMS with two similar microstrip antennas with different iron oxide nanoparticle concentrations of 80% and 30% by weight. The results showed that the polymer nanocomposite magnetic antenna performance not only in the antennas with different operating frequencies were achieved but the use of new polymer nanocomposite materials related with factors such as bandwidth and antenna performance and miniaturization.
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Designing of Microstrip Feed Antenna by Combining Circular and Square Microstrip Antennas

Designing of Microstrip Feed Antenna by Combining Circular and Square Microstrip Antennas

performance aircrafts, wireless communication, missile and satellite applications. However microstrip antennas have disaffects also, narrow bandwidth being a serious limitation. Different methods are projected to improve it, and one of the methods proposed by various researchers is by cutting slots on it. In this paper we have designed a Microstrip Patch antenna using proposed by various researchers is by cutting slots on it. In this paper we have designed a microstrip feed antenna by combining circular and square microstrip antennas.
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Proximity fed Broadband Microstrip Antennas

Proximity fed Broadband Microstrip Antennas

The broadband microstrip antenna is realized by fabricating the patch on lower dielectric constant thicker substrate in conjunction with proximity feeding technique. Using thicker substrates, a formulation for an edge extension length and design guidelines for strip dimensions in proximity fed broadband antennas, are not available. In this paper, first by designing suspended rectangular and circular microstrip antennas on different substrate thickness and at various frequencies in 800 to 6000 MHz frequency band, graphs for an edge extension length are developed. Using them an edge extension length at given frequency and substrate thickness is calculated. The suspended patches were further designed using edge extension length graphs which give closer result with the desired frequency. Further by using proposed equations, proximity fed microstrip antennas were optimized at various frequencies in 800 to 6000 MHz frequency band. Using these optimized designs, a formulation for coupling strip parameters is proposed. By using proposed formulations for edge extension length and strip parameters, proximity fed antennas were re-designed at different frequencies in 800 to 6000 MHz frequency band. In all the configurations, broadband response with formation of loop inside VSWR = 2 circle is obtained. Also by using the proposed formulation, design procedure for proximity fed U-slot cut rectangular microstrip antenna is explained. The U-slot cut antenna gives bandwidth of more than 450 MHz at center frequency of around 1000 MHz. The proposed formulations can be used to design broadband antennas using thicker substrate at any given frequency.
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On the Design of Slot Cut Circularly Polarized Circular Microstrip Antennas

On the Design of Slot Cut Circularly Polarized Circular Microstrip Antennas

two orthogonal modes, to realize CP response. To improve the gain, three layer suspended design of slot cut CP CMSA is also proposed which gives gain of more than 3 dBi. In the reported literature on slot cut CP CMSAs, design guidelines to realize similar CP antennas at any given frequency are not available. Therefore by studying the surface current distributions at two orthogonal modes, formulation in resonant length in terms of slot and patch dimensions for non-suspended and suspended configurations, is proposed. The frequencies calculated us- ing them closely agree with the simulated results. Further using proposed formulations, procedure to design sim- ilar slot cut CP CMSAs at different frequencies and on different substrates, is presented. At respective frequen- cies, it gives CP response with formation of small loop inside VSWR = 2 circle. Thus, proposed formulation
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Study of Impedance-matching and Other Characteristics of Microstrip Antennas

Study of Impedance-matching and Other Characteristics of Microstrip Antennas

Results suggest that undergraduate students in Puerto Rico perceive computer and information technology fields as being oriented to computers, but they don't identify it as m[r]

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Broadband and Dual Band Modified Rectangular Microstrip Antennas

Broadband and Dual Band Modified Rectangular Microstrip Antennas

The more frequently used technique to realize broadband and dual band microstrip antenna is by cutting the slot at an appropriate position inside the patch. In this paper, an in-depth analysis of dual band rectangular slot cut rectangular microstrip antenna and plus shaped slot cut broadband rectangular microstrip antenna is presented. The dual band slot cut antenna is reported to be resonant at 3640 and 4080 MHz. Through the analysis it was observed that the slot modifies the resonance frequencies of TM 11 and TM 02 mode
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Analysis of Broadband Slot Cut Semi Circular Microstrip Antennas

Analysis of Broadband Slot Cut Semi Circular Microstrip Antennas

The broadband designs of slot cut SCMSAs are discussed. It was observed that the quarter wavelength approximation of slot length does not give closer result. Therefore to get an insight into the functioning of slot cut antennas, an analysis of slot cut SCMSAs is proposed. It was observed that the slot reduces second order TM 21 mode frequency of the patch and

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Design and Simulation of Different Shapes Microstrip Antennas   A Literature Review

Design and Simulation of Different Shapes Microstrip Antennas A Literature Review

In this paper we present a survey in the comparison of different microstrip antenna .Here we found Return loss ranging from -16dB to -44dB, Bandwidth percentage 2% to 6%, VSWR (voltage standing wave ratio) < 2 and Gain 3dB to 12dB for different shape Rectangular Microstrip patch Antenna with. This antenna can be used for satellite and wireless communication. Concentrating on theoretical models and performance characteristics of different microstrip patch antenna. Improvement can be done by changing shape as ‘U’, ‘E’ ,T, L , H and changing material so that Return loss(RL), Gain, VSWR(voltage standing wave ratio) Bandwidth, Bandwidth percentage all can be improved.
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