U-slot rectangular patch antenna

In the coaxial line feed technique, the inner conductor of the coaxial strip extends throughout the dielectric and is soldered to the radiating patch, while the outer conductor is coupled to the ground plane. Eventhough the feeding can be given at any desired location inside the patch, the modeling will be difficult using this technique.In the aperture coupled feed, the radiating patch and the microstrip feed line are separated by the ground plane. In this technique, the patch and the feed line is coupled with the ground plane through the slot. The slot should be placed at the centre in order to have low cross polarization but due to multiple layers and the increased thickness, the antenna fabrication is difficult.In the proximity coupled feed, which is otherwise called as the electromagnetic coupling, two dielectric substrates are used and the feed line is between the two substrates among which the radiating patch is on the top of the upper substrate and the ground plane is on the lower substrate. Using this technique, the unwanted radiations can be eliminated but the antenna fabrication is difficult because of the two dielectric substrates. Therefore, the microstrip line feed has been chosen for the rectangular microstrip antenna for better radiation and it is designed using the operating frequency of 5.5GHz and has been simulated using HFSS software.

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In this article, a half U-slot loaded rectangular patch (L × W ) is analyzed using equivalent circuit theory based on model expansion cavity model, in which the performance of half U-slot loaded patch is studied as a function of slot length (L s ), slot width (W s ), notch length (L n ) and notch width (W n ). The theoretical results obtained are compared with the simulated [8] and experimental ones [9].

In this paper we present a novel approach to improve the bandwidth of Microstrip patch antenna using thick substrate and by inserting U slot and H slot in the Truncated rectangular microstrip antenna. By inserting only H slot in the Truncated rectangular microstrip antenna the impedance bandwidth was 21.2% whereas after adding U slot in same design the bandwidth is increase up to 50.7% in the frequency range 1.5 GHz to 2.67 GHz. The U slot is used to tune impedance matching. The radiation pattern has acceptable response at both E and H plane. The antenna is designed at glass epoxy substrate with dielectric constant 4.4, fed by a coaxial feeding technique. Detail of the proposed antenna and the simulated results are presented.

Abstract— The main objective of this paper is to simulate and design a single u-shaped microstrip patch antenna with operating frequency of 5.5GHz. This type of antenna has to be designed using a substrate having a low dielectric constant in order to achieve low return loss. The microstrip antenna consists of the rectangular patch on the top of the dielectric substrate and over which a u-shaped slot has been made to reduce the size of the antenna. The reduction in the size of the antenna results in improved gain and the return loss of the antenna. Therefore, the single u-shaped microstrip patch antenna has a broad bandwidth and can be used for wireless applications. The antenna has been simulated using HFSS (High frequency synthetic simulator) software, a 3D simulator which shows the accurate simulated result compared with other simulation software. Index Terms—- single u-shaped slot, RT Duroid 5880 substrate, HFSS software, 3D simulator, gain, return loss.

A theoretical review on micro strip patch antenna is presented in this paper. Some effect of disadvantages can be minimized. Increasing gain ,bandwidth and lowering VSWR for making patch antenna for application specific is achieved by introducing slots in the geometries of patch antenna. As compared to conventional micro-strip antenna gain is improved, VSWR is reduced so thereby overall efficiency of the antenna increases. Different slots shaped are compared with without slot and it is found that bandwidth of conventional rectangular micro strip antenna can be enhanced respectively using A, C, E, L, and U-patch over the substrate. The E-shaped patch antenna has the highest Gain followed by A, C, L-shaped patch antenna and U-shaped patch antenna.

Microstrip antennas have become attractive candidates in a variety of commercial applications such as mobile and satellite communications. Traditionally, microstrip antennas suffer from low bandwidth characteristic. Experimentally and theoretically, it has been shown that a coaxially fed patch antenna on a foam substrate of approximately 0.08 wavelength thick can enable an impedance bandwidth of about 33%, by cutting proper U-slot in the patch [1, 2]. Moreover, Lee and Lee [3] have experimentally demonstrated the characteristics of two-layer electro-magnetically coupled rectangular patch and reported that relatively large bandwidth could be obtained when the separation between the two layers was less than 0.15 wavelength. Therefore, in the present paper, a stacked U-slot microstrip antenna is presented for broadband operation. The modal expansion cavity model and circuit theory concept have been used to analyze the antenna characteristics. The details of theoretical investigations are given in the following sections.

patch antenna at L-band is designed. The antenna contains a U-Slot and designed with DGS technique to reduce the size of antenna. U-slot etched in the antenna allowed the fabrication on a high-dielectric-constant (10.2) substrate that achieves a reasonable axial-ratio bandwidth. Circular Polarization can be generated on a rectangular patch antenna by truncating two opposite corners of patch. In this paper a comparison has been done between a CP Microstrip antenna with and without U-Slot. At the operating frequency of 1.575 GHz with the size of the patch is 25mm X 25mm, while ground plane of 50mm X 50mm and the thickness of the substrate is 10.2 mm.. The parameters of antenna like return loss, axial ratio, RHCP and LHCP, gain are analyzed using CST MSW Software. The operating frequency is 1.521 GHz.

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This antenna is highly directive antenna with large directivity. Radiation pattern of antenna at different frequencies namely 4.6 GHz, 6.7 GHz and 8.6 GHz have been shown in figure 5(a), 5(b) and 5(c). Table 5.1 shows comparison of results of different designs of making u slots cut applied on rectangular patch to form four u slot antenna as shown in figure 1, 2 and.3. When a transmitter is connected to an antenna by a feed, the impedance of the feed line and antenna must exactly match for maximum energy transfer from the feed line to the antenna. However, when the antenna and feed line do not have matched impedances, part of the electrical energy cannot be transferred from the feed line to the antenna. It is the function of reflection coefficient and tells amount of power that gets reflected. VSWR of antenna as shown in figure 3 is shown in figure 6. Results are analyzed in terms of antenna paramameters as shown in table 2.

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The parameters that have critical influence on the antenna performance are chosen for parametric study. These parameters are: , , , and . Parameters and are responsible for the patch and U-slot electric lengths, whereas changes the patch impedance [11]. Lastly, tells how the U-slot intercepts the current maxima on the patch’s surface. To study their effects on the antenna performance, parametric study is carried out on the parameters mentioned above, using the full wave simulator An- soft HFSS [12]. Simulation results of the reflection coefficient at different values of these parameters are shown in Figs. 3 and 4. From Fig. 3, it is observed that and control the lower and Higher resonant frequencies of the antenna, respectively, as expected. With the proper selection of and , an overlap between both resonances occurred leading to a wide impedance bandwidth. On the other hand, a small variation of the antenna width does not show significant effect on the bandwidth as it is obvious from Fig. 4(a). It should be pointed out that wider variation of is not suggested, because it might excite the horizontal higher order mode. Finally, from Fig. 4(b), the parameter that represents the position of the U- slot on the rectangular patch, controls the separation between the two resonances which consequently affects the achieved impedance bandwidth.

It is derive that the resonant frequency is inversely proportional to the slot length and feed point and at the same time as it increases with increasing the coaxial probe feed radius and slot width [8]. In recent years, some papers were reported for Dual/triple band operation by using single/double U slot in the microstrip antenna. It is seen that the applications which require dual frequency operation with small frequency ratio were designed by using the U slot in a wideband micro strip antenna [9]. Micro strip antennas are suffer from low impedance bandwidth characteristics to increase 5G system applications. To avoid this suffering of antennas, there have been various bandwidth enhancement techniques like coplanar parasitic patches, stacked patches, or novel shapes patches such as the U and H -shaped patches. Here in this design one method is used, called as special feed networks or feeding techniques, to compensate for the natural impedance variation of the patch. To avoid the use of coplanar or stacked parasitic patches we can do the etching process on the patch with U -slot, which increases either the lateral size or the thickness of the antenna. So, sometimes with enhancing the impedance bandwidth, changing the current distribution on the micro strip patch more than one resonant frequency is obtained. In 1995, two scientists named as Huynh and Lee was presented a broad band single layer probe fed patch antenna with a U -shaped slot on the surface of the rectangular patch [10-13].

ABSTRACT: In this paper, a dual frequency resonance antenna is analysed by introducing U-shaped slot in a rectangular patch, the results in terms of return loss and radiation pattern are given. It is observed that various antenna parameters are obtained as a function of frequency for different value of slot length and width; it is easy to adjust the upper and the lower band by varying these different antenna parameters. In the present work variation of substrate permittivity is also studied. All the theoretical results using Matlab are compared with the simulated results obtained from Ansoft HFSS which are in close agreement.

In June 2015 Paper “Design and Fabrication of E-SLOT Microstrip Patch Antenna for WLAN Application” authors Shailander Singh Khangarot, Gajendra sujediya, Tejpal Jhajharia & Abhishek Kumar design an E slot microstrip patch Antenna for WLAN Application. The design targets the WLAN IEEE 802.11 n frequency band (5.47 GHz) simulated design is working from 5.39 GHz to 5.49 GHz whereas fabricated antenna is working from 5.38 GHz to 5.5 GHz which covers the WLAN frequency band. The E-slot microstrip patch antenna has minimum simulated return loss is -23.574 dB at 5.44GHz whereas after fabrication minimum achieved return loss is -24.007 dB at 5.43 GHz. The simulated 2-D and 3-D Radiation Pattern provides omni directional pattern. The proposed E-slot microstrip patch antenna is very promising for various modern communication applications such as WLAN and in C-band applications

In these microstrip antennas, transmission line connects to inner patch and two L shape patch strips. These patch strips have dimensions 75×40 mm and these strips are 10 mm and 5 mm wide respectively. The gap between inner patch and patch strips is 10 mm. The size of inner patch of MSA(a) is 50×50 mm and other ones like MSA(b), MSA(c) and MSA(d) have same size of inner patch that is 55×55 mm. These inner patches have slots of unequal size and shape.

DRA is an excellent radiator as it has negligible metallic loss. It offers advantages such as small size, wide bandwidth, and low cost with the exciting feeding techniques when operating at millimeter and microwave frequencies. Some common feeding mechanisms such as probe feed, aperture slot, microstrip line and coplanar line can be used with the DRAs [1]. DR of any shape can be used for antennas such as cylindrical, hemispherical, rectangular etc. [2–4]. The rectangular DRA offers practical advantages over the spherical and cylindrical shapes, due to flexibility in choosing aspect ratio [5]. There are many papers and investigations, which have been reported on wideband DRA operation [6, 7]. Bandwidth enhancement techniques to improve the bandwidth of dielectric resonator antennas, such as, stacking multiple DRAs [8], using parasitic dielectric resonator elements [9], thick substrate, utilizing special dielectric resonator geometries [10],

Height of substrate effect on the return loss efficiency, while the width of the patch effected directly on the resonant frequency, the effect of the thicker substrate is study from many researchers using different substrates for several applications in the communication using different height and of substrate and varying the height to get improvement in the bandwidth with different patch shapes such as rectangular, circular, fractal and other [2-5]. In the technique of optimizing of patch geometry, reconfigurable, the bandwidth is achieved by introducing the metamaterial phenomena instead of the single patch antenna, metamaterial is used for enhance the parameters of microstrip patch antenna. Metamaterials are artificially structured to have properties which are not found in nature. They are built by periodically arranging unit cells and these unit cells are contain small metallic resonator which interact with external electromagnetic wave [6-11]. Reconfigurable antenna have advantages when compared with the conventional antennas, it provides diversity feature of radiation pattern, frequency and polarization which used in various application in the same time improving bandwidth and gain [12].

we apply the input to the microstrip antenna. It should be less than -10 db for the acceptable operation. It shows that the proposed antenna resonates at frequency equal to 5.5 GHz which gives the measure of the wideband characteristic of the microstrip antenna. The simulated impedance bandwidth of about 260 MHz (5.36-5.62 GHz) is achieved at -10 db reflection coefficient. The reflection coefficient value that is achieved at this resonant frequency is equal to -16.16 db. This reflection coefficient value suggests that there is good matching at the frequency point below the -10 db region. It covers the frequency band for the WLAN application i.e. 5.36-5.62 GHz.

The results shown here are simulated on HFSS software. In HFSS, rectangular patch and partial ground plane are made up of PEC (Perfect Electrical Conductor) and air or vacuum can be used for the radiation box. Figure 2 shows the variation of return loss with frequency. Return loss is the loss of power in the signal returned/reflected by the discontinuity in a transmission line which occurs due to mismatch with terminating load. The gain of the antenna has been studied using a Microstrip patch antenna fabricated on the same substrate.