sides of the rectangular notch are removed, and the desired antenna shape has been obtained as shown in Figure 1(b). The improvement in bandwidth has been achieved by separating a single ground plane of dimension (32 mm × 42 mm) into two parts (32 mm × 15 mm) and (32 mm × 22 mm) with 5 mm separation. The antenna is excited by a coaxial probe at position (0, 4) mm from the center. A prototype of the proposed patchantennas with geometrical parameters are fabricated as shown in Figure 2.
ered by the analysis of the field line approach, the mirror symmetry of field vectors is of significant importance for the reduction of x-pol radiation. The same is true for the dis- tribution of the currents on the patch surface. Figure 17a shows the surface current distribution of the single fed mi- crostrip patch antenna. Figure 17b shows the current distri- bution on the differential fed microstrippatch antenna, ex- cited with two signals 180 ◦ out of phase. By thoroughly in- vestigating the current vector directions from Fig. 17a, the different vector orientations close to the two radiating edges are unambiguous. The patch surface at the feed side shows much stronger horizontally oriented E field vectors (x-pol). This explains the stronger x-pol radiation pattern values from Fig. 3a-3 and the stronger field lines in Fig. 15a. Further- more, the current distribution on the surface of the patch is not symmetrical, so that no perfect cancellation in far field can be reached for the single feed case. On the contrary, the current vectors from Fig. 17b and c are antipodal in direction in the region close to the two opposite probe feeds and occur with exactly the same current strength. Because of the mirror symmetry of the current distributions at the feed areas, the ra- diated x-polarized electrical fields (here with horizontal con- tent) with 180 ◦ phase difference cancel each other in the far field. This explains the x-pol radiation pattern from Fig. 3b-3
Microstrippatchantennas are light weight and low proﬁle antennas that are inherently narrowband in the order of 1%–2% . 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  proposed a novel technique to increase the bandwidth of single-layer patchantennas 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 patchantennas was analyzed in [10, 11]. In [5, 6], the bending eﬀects of narrow- and multi-band patchantennas 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.
if each layer is designed to provide more than one CP band and has wideband behavior, the number of required layers can be reduced. By integrating dual-feed patchantennas with a branch line coupler in a multilayer structure, the dual CP characteristic is obtained in . Here, at the cost of complex structure due to multilayer and dual feed, good CP bandwidth is obtained. In , the design of a dual circularly polarized multilayer microstrip antenna element fed by a gap coupled probe has been presented. The 3 dB axial ratio bandwidth of 2% and 1.5% in the two bands was obtained. Stacked microstrip antenna with dual-band CP behavior is presented in . The dual CP has been realized by combining the stacked conﬁguration with a truncated edge technique at its top and lower patches. In , two miniaturized radiation elements using folded structures are stacked vertically to obtain dual CP band. In both CP bands, the 3-dB axial ratio is around 1%. In , a dual-band circularly polarized single feed microstrip antenna is presented. The dual CP radiations are achieved by introducing a protruding semi ellipse on the edge of the patch and multilayer substrates between ground planes and radiating patch. The stacked patch antenna with dual-band CP is presented in . The dual CP radiations are achieved by embedding two pairs of narrow slots. In , a single layer feed is used to excite a single square patch integrated with a novel asymmetrical slot and two diﬀerently truncated corners to achieve dual-band CP. Triple band CP operation by using a four element trap loaded inverted L-antenna array is realized in . The structure of the antenna is complex due to inverted L-antenna array. Aperture coupled two stacked patches are used to achieve a triple band circular polarization operation . But; the antenna is fed by two feed lines having 180 ◦ phase diﬀerence. In , by inserting two pairs of narrow slots parallel to the edges of the top square patch and cutting slits in the bottom square patch, triple band CP radiation is achieved. In , three stacked patches with a slit and I-slot have been used to achieve three circularly polarized bands. In , the four stacked patches are used to achieve the quad band circular polarization.
This paper presents review work on rectangular shaped microstrippatchantennas. In this paper four rectangular microstripantennas have been studied and analyzed. We start our work with a reference rectangular patch which has six parallel slits of 5mmx37mm, and then we proceed with variation in length and width of those slits. We examine our results on two configurations, single layer and multilayer. With single layer rectangular microstrippatchantennas we obtained dual band broadband antenna which has a maximum bandwidth of 15.13% with a gain of 4.7dBi. Then we shifted our work on multilayer configuration. With multilayer configuration we obtained a multi frequency dual band broadband antenna (in comparison to single layer configuration) which have four resonant frequencies and have maximum bandwidths of 27.08% with a gain of 5.69dBi. All four antennas are simulated in IE3D simulation software, and all Antennas are designed on FR4 substrate.
The aim of this project is to design a circular microstrip antenna for WLAN. Circular patch antenna is one of the popular patchantennas that receive a lot of attention not only as a single element but also in array. In circular microstrip antenna, there is only one degree of freedom to control which is the radius of patch. Coaxial probe feed is chosen due to its ease of fabrication and easily matching by putting the feed at proper location.
Schematic of the proposed structure in  is indicated in Fig. 1(a). It contains two coaxial probes on a singlepatch and two inverted U-slots. The authors of  determined the antenna bandwidth from the reflection coefficient. However, as well as the reflection coefficient, isolation between the two inputs should have been examined, to indicate that the structure is radiating, instead of transmitting the power from one input to the other one. The effects of this ignorance can be observed on the realised gain and active𝑆-parameters as will be indicated, subsequently. Furthermore, the performance of the antenna is compared with a simple 50 Ω microstrip line excited by two probes, as depicted in Fig. 1(b). Separation between the probes, thickness of the substrate, ℎ, and relative permittivity, 𝜖 𝑟 , are similar to the U-slotted patch (ℎ = 1.57 mm and 𝜖 𝑟 = 2.2). ANSYS HFSS is used
Dual-polarized resonant cavity antennas for dual-band operation have been reported in the literature by using double  or single layer  PRS. Similarly, wideband dual-polarized resonant cavity antennas have also been reported with diﬀerent PRS structures. In , wideband dual-polarized RCA was reported for 5G wireless local networks (WLANs) application. The feed antenna consisted of two orthogonal bow-tie dipoles over ground plane. The measured bandwidth was 5.3–6.3 GHz (17.2%). The gain of the antenna was 12.1 dBi at 5.5 GHz. In , a broadband resonant cavity antenna operating at Ka band with high gain and dual-polarization was reported. A double-sided complementary-circular patch PRS was used in the above mentioned antenna to enhance the directivity and radiation bandwidth. Further, a square patch coupled with two orthogonal slots and fed by two microstrip lines was also applied as the primary feed to achieve dual-polarization operation. The impedance bandwidth of the
Complementary split spiral Resonator (CSSR) unit cell  In  MTM are nothing but unit cell of specific shape and material which are periodically arranged at intervals shorter than the specified wavelength. Since MTMs are generally not available in nature and one has to imposed them, they can be classified asi) Single negative MTM (SNG) ii) Double negative MTM (DNG) iii) Electromagnetic Band-gap MTM (EBG) Surface waves and radiated wave are the two causes for increased mutual coupling which affect the antenna performance.Thin Wire (TW), split ring resonator (SRR), omega, mushroom, Fishnet and many more. These structures can be constructed using either
With the rapid development of wireless communication systems, circularly polarized (CP) antennas have gained much attention than ever. It is because they not only are capable of allowing for better mobility and weather penetration, but also alleviate multipath distortion and polarization mismatch losses between the receiving and transmitting antennas. In recent years, many microstrip CP antennas of the single-fed type are reported in the literature, such as a corner-truncated square patch with a novel coaxial feed , wideband CP microstripantennas with annular-ring slot or cross-shaped slot [2– 4], stacked CP microstripantennas using a new C-type single feed or a S-shaped impedance matching network [5–7], and a broadband microstrip antenna using an artificial ground structure with rectangular unit cells . However, these CP antennas have relatively narrow impedance and AR bandwidths (generally less than 10%). For microstripantennas of the dual-fed or tri-fed type [9–11], circular polarization can be generated with the use of an external polarizer, resulting in wide impedance and AR bandwidths. A circular patch antenna, employing four sequentially rotated L-probes and a novel wideband 90 ◦ hybrid feed network, delivers 10-dB impedance and 3-dB AR bandwidths of 79% and 82%,
Circularly polarized (CP) antennas have been receiving much attention due to their abilities to eliminate the arising multipath effects and allow flexible orientation of the transmitter and the receiver. As far as single-fed microstripantennas are concerned, circular polarization can be generated with perturbation technologies such as using a nearly square patch , truncating patch corners , adding stubs or cutting notches along two opposite edges  and embedding a diagonal slot . However, the simple single-fed CP antennas have inherently narrow 3- dB axial-ratio (AR) bandwidth of less than 2% .
Stacked microstrippatch 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 microstripantennas 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 singlemicrostrip antenna which is 0.25Ghz. we also designed singlemicrostrip antenna and 2x1 microstripantennas 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 microstripantennas with different shaped parasitic elements on it and the bandwidth variations , return loss are studied from the simulated results.
The main objective of this project is to design an efficient microstrip rectangular patch antenna by adding in many patch (4xN) antennas in array for WiMAX application at 2.5GHz. The design’s performance will be more focus on return loss, Voltage Standing Wave Ratio (VSWR), bandwidth, directivity, radiation pattern and gain and will be simulated and tested by CST Studio Suite software.
In recent development of wireless systems, the requirement for miniaturized devices within high data rate transmission and low power consumption is becoming more and more important. Ultra-wide band (UWB) systems have received a tremendous attention in both industries and academia due to their ability for higher data transmission and reception of signals with less power consumption (<-41.3dBm/MHz) . UWB systems have other advantages such as easy integration with system circuits, better radiation characteristics, and wider bandwidth to support various applications like medical imaging systems, mobile systems, vehicular radar systems, sensor network, and RFID readers especially for short-range applications ,,,, high-resolution reliable data. According to U.S FCC regulations , the frequency band allocated to UWB systems ranges from 3.1 GHz-10.6 GHz , and 6.0 GHz-8.5 GHz for European regulations. In general, UWB antennas are an intentional radiator that, at any point in time, have a fractional bandwidth of at least 20% or has -10 dB bandwidth greater 500 MHz regardless of the fractional bandwidth .
8.7dB and also lowest loss with a return loss of -19.8dB. This low loss is also confirmed by the VSWR value of 1.2. It is also evident that the gain of the antenna reduces as the value of the dielectric constant increases, from 8.7dB for Foam to 2.2dB for FR4, when all other design parameters like the frequency and the thickness are kept constant. This result shows that the lower the dielectric constant the better is the gain and the radiation efficiency. Also the result shows that microstrippatch antenna exhibit a wide radiation pattern and high directivity.
Microstripantennas  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. Microstripantennas 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 patchantennas widely implemented in many applications, such as high performance aircrafts, wireless communication, satellite and missile applications. However microstripantennas 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 MicrostripPatch antenna using proposed by various researchers is by cutting slots on it. In this paper we have designed a MicrostripPatch antenna using circular and square slots on the rectangular microstrip antenna.
A rectangular patch, as an example for an irregular patch antenna, is chosen due to the reason that an analytical port impedance, called cavity model, available as given in  or (18) in , can be regarded as an approximation to the impedance Z in U in the probe circuit model in case of electrically small probes. Furthermore, the patch antenna can be analyzed by a two dimensional (2D) FEM for extraction of Z in U using the uniform-current model. Then, the probe circuit derived in this paper can be used to obtain more accurate probe input impedance using (25) as it includes the capacitance, C p , due to the higher-order modes.
Figure 1 shows the evolution of circular semi-ring monopole antenna with a novel wing-shaped ground plane be fed by microstrip line which has been studied in this paper. A basic circular ring monopole with a radius of r 1 , r 2 and a 50 Ω microstrip feed line are printed on the same side of 22×41 mm dielectric substrates. Duroid was used as a dielectric substrate with a thickness of h = 0.87 mm and a relative permittivity of ε r = 3.8. w f , h f and h 2 were chosen at 2.6, 20.4 and 3 mm in order
As a result the demand has been increased for broad band WLAN antenna that meets all the desired requirements. The broadband antenna are required to be compact, low profile directive for high transmission efficiency and designed to be discreet, due to these well met requirements couple with the ease of manufacture and repeatability makes the micro strip patchantennas very well suited for broadband wireless applications.