conventional microstrip patch antennas

Due to rapid development of modern wireless communication technologies, low cost, light weight and small size wideband antennas are of great demand. Microstrip patch antennas are developed in response to this need. Their planer profile configurations attract commercial, industrial and medical applications. However, the main limitation of the conventional microstrip patch antennas is narrow bandwidth that restricts its operation where wider bandwidth is required. To overcome their inherent limitation of narrow bandwidth, many techniques have been proposed and investigated such as by using lower value of dielectric substrate, increasing the thickness of substrate [1], utilizing an impedance matching networks and different types of feeding techniques [2–5], use of stacked and coplanar structures [6], loading of slot and notch [7, 8]. These techniques have some limitations except loading of slot and notch, because it enhances bandwidth without increasing the volume of the geometry. For these reasons, several structures have been reported by the research groups such as E-shaped antenna [9–12], E and H-shaped antennas [13], C-shaped antenna [14], notched semi-disk antenna [15], E-shaped ground penetrating patch antenna [16], ψ -shaped antenna [17], V-shaped and half V shaped antennas [18], W-shaped antenna, etc. [19] in which they achieved broad bandwidth. These antennas are fabricated on thin microwave substrates having two or more adjacent resonant frequencies which are excited near the fundamental frequencies. These closely excited resonating frequencies are combined to provide enhanced bandwidth. The concept of the proposed antenna structure has been extracted from the above discussed antenna shapes.

Directive dual-polarized planar antennas are used in high speed wireless systems to mitigate the effect of fading due to multipath propagations. These types of antennas are also used in Radars to extract the information about target’s multiple features, whereas conventional planar antennas, such as microstrip patch antenna and slot antennas, suffer from low directivity and gain because of small aperture, surface wave excitation and back lobe radiation. On the other hand, reflectors and substrates made up of artificial surfaces (i.e., Artificial Magnetic Conductors and Frequency Selective Surfaces (FSS) etc.) can be used to reduce back lobe radiation [1] or surface waves [2] and increase directivity and gain. However, the effect of back lobe radiation and surface waves on the directivity/gain performance of the antenna is less than the effect of aperture size. The aperture size of a planar antenna can be increased by using antenna array configuration or resonant cavity antenna configuration. Resonant cavity antenna (RCA) configuration consists of planar feed antenna loaded with 1-D electromagnetic bandgap structures (EBG) [3, 4], partially reflecting surfaces (PRS) or FSS [5] as superstrates. These antenna structures are simple in design and construction compared to array configuration. Further, RCAs have low loss and high gain which make them ideal for wireless and Radar applications.

In this work, a precise and effective approach is applied to calculate important parameters of circular patch an- tenna. Microstrip patch antennas of all shapes are widely used in communication systems where their small size, conformal geometry and low cost can be used to advan- tage. Due to the recent availability of low loss, commer- cial microwave ferrites there is an increasing interest in the performance of the patch antennas printed on ferrite substrates. Although some work [1-6] have been per- formed for microstrip antenna with GA approach for the patch antennas without magnetic biasing but analysis of almost all important parameters for ferrite substrate under magnetic biasing for circular patch antenna is new one. Present analysis also incorporate the dispersion effects due to magnetic field biasing in the form of effective propagation constant (k) which is not discussed in the referenced articles. Some similar referenced works [7-11] also have done mathematically or by conventional me- thods for optimization but this technique is rather precise, accurate and sensitive to optimize parameters of patch antenna as well as other type of antenna also.

This project is about to design of a microstrip patch antenna on the non- conductive textile substrates at the operating frequency 2.45 GHz which is for wireless local area network (WLAN) application. There are certain fabric materials in the market that can be use to patch the microstrip antenna such as Nora, felt, fleece and etc. Those fabric materials have relative permittivity characteristics that make it suitable for wearable antenna. The main objective of this project is to design, simulate, fabricate and analyze the microstrip patch antenna at frequency 2.45 GHz using textile as the substrate. The proposed fabric material for this project is felt fabric. The felt fabric is selected because it has constant thickness and stable relative permittivity. The 2.45 GHz unlicensed band is utilized for the development of this wearable antennas. The used of FR4 as the substrate in conventional antenna is not suitable for wearable system because of limited body movement problem. To overcome this problem is by changing FR4 substrate with textile substrate. The measurement results for fabricated antenna have a slightly different with the simulation result. The frequency of the simulation result is 2.45 GHz, but the frequency of measured result has shifted to 2.6 GHz. However, some recommendation was made in order to improve the performance of the antenna.

The application of this type of antennas started in early 1970’s when conformal antennas were required for missiles. Rectangular and circular micro strip resonant patches have been used extensively in a variety of array configurations. A major contributing factor for recent advances of microstrip antennas is the current revolution in electronic circuit miniaturization brought about by developments in large scale integration. As conventional antennas are often bulky and costly part of an electronic system, micro strip antennas based on photolithographic technology are seen as an engineering breakthrough.[4]

Despite its advantages, the performance of UWB systems are seriously degraded by multipath fading environment [8].Without increasing the bandwidth or transmitted power, the quality of communication in UWB systems can be improved by means of Multiple Input Multiple Output (MIMO) technology [9]. It uses multiple antennas at both transmitter and receiver, and requires higher isolation between antenna elements for better space diversity[10]. Different decoupling techniques for enhancing isolation between elements have been reported in literature. . In [8],[11], a rectangular shaped ground plane with an extruded T-shaped stub have been reported to enhance isolation below -20 dB and providing an envelope correlation coefficient (ECC) less than 0.02 and diversity gain (DG) greater than 9.95 dB. The Elements are oriented orthogonally

Microstrip patch antennas with a finite ground plane which can operate as a monopole antennas are a good candidates for commercial units in terms of their size, but they have a narrow impedance bandwidth, usually less than 5%. Nowadays, various bandwidth widening techniques are presented. Probe compensation, coplanar parasitic patches, stacked parasitic patches, the U-slot patch antenna, the L-probe coupled patch, the M endering-probe fed patch, aperture coupled patches and ground plane modification are such techniques, which are totally investigated in many research projects [2, 5, 18– 20, 23–26].

Microstrip antenna is an ideal antenna that is suitable for use in an application of WLAN and telecommunication due to the simple characteristic of the antenna which is easy to fabricate, easy to feed, smaller size, light weight, low cost and designer flexibility.

Three widely used probe feeding models have been compared in [7] for patch antennas. The simplest one is called uniform-current model which assumes a constant current source along the probe. while it is very easy to implement in numerical methods such as finite element method (FEM) and finite difference time domain (FDTD), the uniform current can only excites the zero-order parallel plate model, i.e., it neglects all the higher-order modes. This means although it can predict the radiation pattern correctly, it cannot get accurate input impedance for a probe-feeding patch antenna with thick substrates [7, 8].

Additionally, CP radiation can also be achieved by using an L- shaped feeding strip when no perturbations are added to slots [8–10]. Though wide AR bandwidths of 40% [8], 2.6% [9] and 6% [10] are obtained, the capacitance value between the bent strip and ground is very critical to obtain a low axial ratio and good impedance matching [8]. In literature [11], a pair of hat-shaped patches is added to the ring slot for CP and the bent feeding line is deformed for impedance matching. A CPW-fed square slot antenna with lightening-shaped feeding and two symmetrical F -shaped slit embedded in opposite corners for wide CP bandwidth is proposed in [12]. The complex antenna has numbers of parameters to control and the design procedure is complicated though wide AR bandwidth of 51.7% is obtained. A parasitic patch embedded in the wide-slot antenna can enhance the bandwidth [13] and when a rectangular patch [14] or a cross-shaped patch [15] is loaded in the square slot, wide AR bandwidths of 12% and 12.4% are obtained. In [16], four unequal linear slots are located around the annular-slot and the 3-dB AR bandwidths for the dual- frequency bands with inverse CP are about 6%. The slot antenna with two inverted-L grounded strips around two opposite corners of the slot [17] and another diamond-shaped slot [18] antenna achieve AR bandwidths of 25% and 68%, respectively. The two mentioned antennas can be regarded as slots with perturbations on edges. But the wide bandwidths may be mainly due to the CPW feeding technique in some way and the radiation patterns are unsatisfactory.

The radiating patch is made up of a conducting material which can be copper or gold, and different feeding methods can be employed to excite the patch [8, 10]. The substrate is used primarily to provide adequate spacing and mechanical support between the radiating patch and the ground plane. More often, substrate with high dielectric-constant materials are used to load the patch and reduce its size at the expense of the bandwidth and radiation efficiency [13, 14]. While a

The first resonant frequency of first order fractal and second order fractal antenna are compared with the well known Microstrip patch antenna. It has been shown that two presented antennas have lower first resonant frequencies that cause a noticeable reduction in the size of the antennas. A patch antenna can be achieved by the microstrip

This project been proposed to design of microstrip rectangular patch antenna with centre frequency at 2.5GHz for WiMAX application by using Graphene. The array of 4 by N (4xN) patch array microstrip rectangular antenna with microstrip line feeding based on quarter wave impedance matching technique will be done and simulated by using Computer Simulation Tool (CST) software [15] . This design will

Stacked microstrip patch antenna that has a wide band width in the spectrum was designed by Ansoft HFSS. We used a dielectric constant substrates of 2.2 for a main patch and a parasitic patch. We designed a 2x1 array microstrip antennas and the designs were simulated using HFSS , the results were impressive to see that the bandwidth obtained is 1.17 Ghz compared to the bandwidth obtained from single microstrip antenna which is 0.25Ghz. we also designed single microstrip antenna and 2x1 microstrip antennas with a slot in the driven element and the bandwidth variations are studied. The bandwidth is increased to 1.19 GHz. We also designed multilayered microstrip antennas with different shaped parasitic elements on it and the bandwidth variations , return loss are studied from the simulated results.

Artificial Neural Network (ANNs) techniques are recently indicating a lot of promises in the application of various micro-engineering fields. Such a use of ANNs for estimating the patch dimensions of a microstrip line feed rectangular microstrip patch antennas has been presented in this paper. An ANN model has been devel- oped and tested for rectangular patch antenna design. The performance of the neural network has been com- pared with the simulated values obtained from IE3D EM Simulator. It transforms the data containing the di- electric constant (ε r ), thickness of the substrate (h), and antenna’s dominant-mode resonant frequency (f r ) to

b The loading of the surface of the printed element with slots of appropriate shape Antenna array used for worldwide interoperability for microwave access WiMAX and wireless local area n[r]

Dr. Komal Sharma received the Ph.D. degree in the field of Microstrip Antenna from the University of Rajasthan, Jaipur, in 2012. Currently, she is a Reader of the Department of Physics at Swami Keshvanand Institute of Technology Management & Gramothan, Jaipur. She has been working on the design and development of microstrip patch antenna of various shapes and has published more than Thirty Five Research Papers in the reputed International Journals, national journals and Conferences. Her research interest includes Microstrip antenna for wireless communication for various applications.

Abstract–An important challenge in communication industry is to reduce the total size of devices. Similarly array size reduction has attracted increasing interest in recent years. Placing elements of an antenna array close to each other is certainly one way to reduce the total size of an array antenna. However, one of the factor called mutual coupling depends on inter element separation and relative orientation, causes undesirable effects on antenna characteristics. Therefore, within a compact structure of an antenna, reduction in mutual coupling in microstrip antennas is a major challenge.

slot is cut in the center of the patch. The vertical and horizontal lengths of the slot are 6.8 mm and 7.6 mm, respectively. The patch is excited by a 50 Ω coaxial probe, which is located at 0.3 mm off the center of the patch. The planar patch is numerically finalized to obtain about 43% impedance bandwidth. This U-slot patch antenna is then mounted on a cylindrical structure with a radius r and an arc angle α , as shown in Fig. 1, where the antenna is bent along its H -plane, i.e., the patch width. The planar and conformal wideband antennas are numerically analyzed using a finite-element based full-wave electromagnetic solver, ANSYS HFSS v.16 [12]. The scattering parameters, |S 11 | , for

Microstrip antennas [6] are becoming increasingly useful because they can be printed directly onto a circuit board. These antennas are also becoming very pervasive within the mobile phone market.[1] Microstrip antennas are low cost, low profile & simply fabricated. These are relatively cheap to manufacture & design because of the simple 2-dimensional physical geometry. These are also less weight, conformal shaped, capable of dual & triple frequency operations. These are extremely efficient, easily integrated to circuits, easy to planer & non- planer surfaces and are compatible with MMIC design. All these features make patch antennas widely implemented in many applications, such as high performance aircrafts, wireless communication, satellite and missile applications. However microstrip antennas have disadvantages also, narrow bandwidth being a serious limitation. Different techniques 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 Patch antenna using circular and square slots on the rectangular microstrip antenna[2].