conformal microstrip patch antennas

Microstrip patch antennas are light weight and low profile antennas that are inherently narrowband in the order of 1%–2% [1]. In emerging wireless communications and radar systems, however, large bandwidths are necessary to transmit massive amounts of data and to enhance the resolution in radar systems. Hyung and Lee [2] proposed a novel technique to increase the bandwidth of single-layer patch antennas to 30% by cutting a U-shaped slot from the patch. The U-slot antenna has been further studied and analyzed to develop design procedures [3, 4] to estimate the structure’s multiple resonating frequencies that are eventually coupled together to widen the frequency band. Recent advances in the field of wearable technology have created a strong demand for antennas that are flexible and mechanically robust for long-time use. The bending effects on the rectangular patch antenna were studied for wearable applications in [5–11]. A cylindrical-rectangular cavity model for bent patch antennas was analyzed in [10, 11]. In [5, 6], the bending effects of narrow- and multi-band patch antennas on the input impedance, resonant frequencies, and radiation performance were studied, where the shift in the resonant frequencies was well explicated. However, the bending effect on the impedance bandwidth of wideband antennas has not been investigated, to the best of our knowledge.

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.

The use of microstrip patch antenna has been much increased these days in various applications such as satellite, spacecraft, mobile radio, wireless communication and missile applications as it fulfills the certain requirements or specifications such as small size, low weight, low cost.[1] Basically Microstrip patch antenna is a low profile antenna with low weight, low fabrication cost, also it is conformal to the surface of objects, easy of fabrication and installation and capable of multiband frequency operations [8] and it is well suited for the applications like WLAN, Wi MAX, Bluetooth etc.[6] Apart from these advantages, the microstrip patch antenna has various limitations, for example, low power handling capacity, low gain, narrow impedance bandwidth, etc.[5] There are various possible methods that can be implemented to enhance the impedance bandwidth of microstrip patch antenna,for example, slotted patch [7], increasing the height of substrate and stacking [1], defected ground surface.[5] However, the implementation of the above listed techniques can make the antenna design complex and sophisticated.[5]

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].

watches, smart bands, On-body health monitoring devices etc. This has led to the idea of flexible electronics where the devices are designed in order to comfortably fit on various body parts. In order to satisfy the demand for wearable devices, conformal antennas are also required. The developed conformal antenna design can be employed for wearable devices that work in 5G communication band.

A microstrip antenna integrated in the 3D orthogonal woven fabric was successfully fabricated in this study. This type of antenna is aimed to work for wearable or conformal antenna applications. The dielectric constant of the 3D fabric substrate was first calculated, which is the pre-required parameter for the design of the patch size. The simulated results of the return loss and radiation pattern showed good agreement with the measured values. The return loss, radiation pattern and gain of the antenna were in the required range of the common single-element microstrip antenna. This type of integrated antenna is expected to be a wearable antenna applied in the army telecommunication and other applications for smart textile antennas.

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]

The microstrip inset feed is used for exciting the antenna model and adjusted at 50 ohm impedance matching. The combination of these arrangements makes the antenna configurations work as a cavity resonator. Initially, the dimension specifications of single and dual antenna models are calculated and validated on the planar surface [4, 5]. Both antenna models are transformed step by step from planar surface to cylindrical surface, and the corresponding parametric variations at different diameters are noted down. For dual patch antenna, the mutual coupling is an important concern which depends on the inter element spacing and angle of mounting curvature. In this case, the H -plane antenna is considered with fixed inter element spacing at half wavelength for maximum radiation. The SIW technology effectively controls the surface waves and hence minimizes the mutual coupling effect for dense antenna array design.

Surface waves and near fields can lead to coupling between coplanar and patch antennas [1]–[3]. Near field coupling arises when an antenna is placed in the near-field zone of other antenna. This coupling is strong in situations where the antennas are placed on dielectric substrates having low permittivity [3]. In such cases, the coupling can result in degradation to the antenna’s radiation characteristics. Apparently surface waves are weakly excited in very thin grounded dielectric substrates, space- waves dominate as well as produces strong coupling when antennas are in close area. The study of the mutual coupling problem started several decades ago, and several research efforts have been devoted to combat the mutual coupling between coupled antennas to improve antenna radiation characteristics.

Abstract—This paper presents a comparative study of rectangular base desktop shaped broadband patch antenna (Antenna1) and triangular base desktop shaped broadband patch antenna (Antenna2). Apart from base dimensions all parameters of both antennas are constant. The broadband characteristics are achieved by introducing two parasitic ground planes and notches are etched on the radiating patch. Both antennas are simulated, fabricated and tested for obtaining the desired performance. The designed Antenna1 shows bandwidth of 39.97% (4.95 GHz to 7.42 GHz) whereas an improved bandwidth of 49.0% (4.53 GHz to 7.47 GHz) is achieved through Antenna2. Further, gain and radiation pattern of the two antennas are compared and discussed. The effect of inclination angle ‘ α ’ on Antenna2 characteristics in obtaining the improved bandwidth is also studied. The proposed antennas are simulated, and results are verified experimentally.

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.

Antenna is a transducer designed to transmit as well as receive electromagnetic waves. Also the antenna is transitional structure between free space and a guiding device. The guiding device or transmission line may be coaxial line or hollow pipe. Microstrip patch antenna consists of metallic patch on ground substrate. The patch can take many different shapes. This antenna can be mounted on the surface of high performance. It is a popular printed resonant antenna for narrow-band microwave wireless links that require semi- hemispherical coverage. The effective techniques used for the enhancement of the bandwidth are the utilization of stacked, shorted patches, and extra microstrip resonators. The technique of stacked patches is based on the fact that the bandwidth is in general proportional to the antenna volume measured in wavelengths but at the same time a relatively large volume is a disadvantage for many applications. Superior to these methods is the techniques of slot loading or texturing the patches by slits because they ensure the small size and the low profile of the antenna. The utilization of additional parasitic patches of different size directly- or gap- coupled to the main patch is an effective method but results to an increased antenna size which would also be undesired a) The texturing of narrow or wide slits at the boundary of the microstrip patch (Suspended technique) & using capacitive fed.

Abstract—Square slot antennas with modified edges for broadband circular polarization are presented. Slots with only stubs or notches are studied and it is found that the axial ratio (AR) bandwidth is quite sensitive to the perturbations of the stubs and notches. To further enhance the AR bandwidth, slot antennas with combination of stubs and notches are proposed and wide 3-dB AR bandwidth of 15.5% (2.45–2.86 GHz) is obtained. By placing a conducting reflector at the rear of the slot, another modified square slot antenna is designed for practical applications, which achieves a 3-dB AR bandwidth of 6.5% (2.38–2.54 GHz) and peak gain of 8.7 dBic. Agreement between simulated and measured results is satisfactory.

In this work, limitations of the inset fed method have been outlined. A simple but efficient idea for particular configurations is presented and implemented, which allows to increase the bandwidth and match the feeding microstrip. The design procedure allows to graphically adjust the coupling loop to the desired CF. Degradations in the radiation pattern are small. While the gain decreases slightly, bandwidth increases, and the current distribution on the main patch shows a TM 10

Microstrip patch antennas are widely used because of their many advantages, such as the low profile, light weight, and conformity. However, patch antennas have a main disadvantage i.e. a narrow bandwidth. Researchers have made many efforts to overcome this problem and many configurations have been presented to broaden the bandwidth. A new, compact, simple and gap coupled broadband microstrip patch antenna with multilayer stacked configuration is presented in this paper. The computer simulation results show that the antenna can realize wide band characters. The Return loss, smith chart, impedance, radiation pattern, gain, VSWR and directivity of such an antenna are studied. The possibility of increasing bandwidth, gain and directivity of the microstrip patch antenna using line feed techniques is examined. Percentage bandwidth of antenna is approximately calculated using line feed technique. ANSOFT HFSS 13.0 is used in order to design the antenna and simulate the antenna characteristics.

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

A wideband microstrip antenna in the form of a CPW-Fed octagon ring is presented in this study. The proposed antenna shows wideband performance for a return loss of less than 10 dB in the frequency band 3.2 GHz to 18 GHz. The proposed antenna's simulated and calculated results show a good agreement on return loss, antenna gain, and radiation patterns. Over the entire operating bandwidth, the radiation patterns are satisfactory. The proposed antenna gave approximately 130 percent impedance bandwidth, which enables its use in various wireless applications.

Fig.1 In addition, using the fact that the electric current density on the microstrip patch has no normal component along the edge of the patch, the tangential magnetic field is assumed to be negligible not just at the edges of the patch but all the way down to the ground plane. Therefore, the region between the patch and the ground plane can be surrounded by perfect magnetic conductor (PMC) wall that would not significantly alter the original field distribution under the patch, and hence forms a cavity. Consequently, once the cavity is formed as the model of the patch antenna, the fields in the cavity and subsequently other electrical characteristics can be easily obtained by the well- known solution of the cavity.

antenna generated with a Koch curve is loaded with a resistor to produce a traveling wave. The traveling wave nature of the antenna enables the antenna to operate over a wide bandwidth without nulls in the elevation pattern. In Direction Finding applications broadband antennas with omni azimuthal coverage are preferred antennas. The suitable number of broadband antennas are placed in circular bay form to achieve good DF accuracy and lesser ambiguity in phase comparison DF system. In bay form, antenna pattern distortion occurs due to mutual coupling between antenna elements of antenna bay. The proposed antenna offers some front to back ratio in azimuth plane radiation patterns with good omni directionality. This property of the antenna reduces the risk of pattern distortion upto some extent while placing the antennas in bay form in back to back fashion and hence is a good candidate for Direction Finding applications.

ABSTRACT: In this paper a design of proximity coupled equilateral triangular microstrip antenna with diamond shape slot on the radiating patch is studied. The antenna consists of two layers with glass epoxy material of thickness (h) 0.32cm each forming total thickness of 0.64cm. The proposed diamond shape slot loaded antenna resonates at two different frequencies 2.95GHz and 5.91GHz with bandwidth of 8.87% and 11.05% respectively with compared to that of conventional microstrip antenna which resonates at 3.07GHz with bandwidth of 9.15%. These antennas are simulated by using Ansoft HFSS electromagnetic simulation software. The antenna parameters such as return loss, bandwidth and radiation pattern are discussed and presented.