Horizontally Polarized Omnidirectional Antenna Using Slotted Rectangular Patch and Defected Ground Structure

In this paper, we have proposed a Slotted Microstrip Patch Antenna with a Defected Ground Structure (DGS). Here, we have integrated the concept of DGS and Slotted Patch Antenna in order to get enhanced bandwidth and gain. The proposed antenna consists of a microstrip fed slotted rectangular patch with E-shaped cut in the ground plane. The performance of this antenna is discussed and analyzed with the variations in patch width and number of slots. The variations in Return Loss (S11), Radiation Pattern and Gain of the designed antenna are analyzed for different case studies. The antenna shows a dual band characteristics having a return loss of below −20 dB at 3.2–3.5 GHz and below −10 dB at 5.6–5.8 GHz, which is suitable for IEEE 802.16 WiMAX and IEEE11p WLAN applications. CST MWS 2015 is used to simulate the antenna structure.

In this paper a novel design of a Slotted Rectangular Microstrip Patch Antenna with perturbation in ground plane is described which increases the interference rejection frequency bandwidth. A comparative study is also shown between two antenna with identical radiating element, one with a perturbed ground plane and another without perturbation. The proposed antenna is designed for operation at both the signal frequencies 1.9 GHz and 2.4 GHz. The results are obtained by modeling and simulation using Ansoft HFSS software tools. The result shows almost 13.5% interference rejection bandwidth at −10dB return loss without ground plane perturbation. Rejection bandwidth increased to 18.2 % with the use of ground plane perturbation in the same patch antenna.

This chapter presents the study of performance parameters of stub loaded oval-shaped patch antenna using dumbbell-shaped metamaterials (MTM), electromagnetic bandgap structures (EBG), and defective ground structures. Metamaterials are loaded inside the substrate that is mounted on the partial ground plane. EBG and DGS structures utilize full ground planes. The partial ground plane has the dimensions of 10 × 6 × 0.035 mm3 and the full ground plane has the dimensions of 10 × 12 × 0.035 mm3. Many features like impedance bandwidth, gain, axial ratio, and miniaturization of the proposed patch antenna are studied using metamaterials, electromagnetic bandgap structures (EBG), and defective ground structures. The appropriate structure will be chosen depending on the wireless application. Metamaterial loaded patch antenna is recommended for wide bandwidth applications, patch antenna mounted the EBG ground is recommended for small antenna applications, and patch mounted on the DGS ground is recommended for high gain applications.

: This paper presents a two element microstrip antenna array using trapezium shape defected ground structure (DGS). The DGS is inserted in the ground plane between two elements of antenna array. Insertion of the DGS is intended to suppress the mutual coupling effect produced by antenna array. Simulation and measurement results were taken and compared between antenna array with and without DGS. Measurement results show that the antenna with DGS compared to antenna without DGS can suppress mutual coupling effect to 7.9 dB, improve the return loss to 33.29% from -30.188 dB to -40.24 dB and axial ratio bandwidth enhancement to 10 MHz. This bandwidth enhancement is achieved from frequency 2.63 GHz – 2.67 GHz for antenna without DGS and from frequency 2.63 GHz – 2.68 GHz for antenna with DGS. In addition, the DGS antenna also improved the antenna gain to 0.6 dB. The results show that the implementation of the trapezium DGS can improve the radiation properties of the antenna without DGS.

Recent demands for miniaturized, lightweight, high data rate, and reliable wireless devices motivated researches and designers of wireless systems to adopt the use of multiple input-multiple output MIMO antenna arrays with close proximity of each other. One of the difficulties is to overcome the problems associated with the low isolation between any two closely spaced antennas. The low profile, small size, ease of fabrication, and simplicity of design encourage the use of the IFA/PIFA antennas. In this paper, two vertical IFA antennas with close separation of λ o /15 ( o /2) fed by coaxial lines are combined in an array operating at the frequency of 2.5 GHz. The two antennas are deployed on a ground backed substrate of 50 mm × 50 mm in length and width respectively and a thickness of 1.524 mm with a relative permittivity, e r of 10.2. Each IFA consists of a monopole as the main radiator with a length of 38 mm and a diameter of 1.22 mm placed 11 mm above the ground plane. The separation between the feeding point and the grounded end of the radiating element is 10 mm. The consequence of positioning the antenna in the proximity of each other is the high mutual coupling. To decrease the resulted effects, a new Defected Ground Structure (DGS) has been proposed. A rectangular slot of 32 mm and width of 1.5 mm with a strip line of 29 mm in length and a width of 1 mm have been introduced to the ground plane. The final proposed array with the DGS is shown in the attached figure. The Defected Ground Structure (DGS) has the effect of reducing the interaction between the antennas, main radiators, by restricting the current flow in the ground plane. A parametric study has been carried out to obtain the optimum dimensions of the structure using Ansys High Frequency Structure Simulator (HFSS). The S-Parameters of the design are shown in the enclosed figure. The antenna has an operating frequency of 2.5 GHz. A total isolation level of -22 dB has been achieved by the proposed structure at the operating frequency. The array with the proposed ground structure provides a gain of 3.9 dB at 2.5 GHz when the two ports are excited. This structure is a good candidate for reducing the mutual coupling between two vertical IFA for application utilizing MIMO techniques.

A highly miniaturized microstrip patch antenna is presented in this paper. The antenna is miniaturized using defected ground structure and shorting pin techniques. The defected ground structure is formed by making a U slot on the ground plane. The substrate taken is Rogers and the feed technique used will be coaxial. The antenna has dual band operation also. The antenna is having omni directional radiation pattern and the return loss considered is −10dB. The antenna has resonant frequencies at 2.4 GHz with a return loss of −13.6 dB and 5.2 GHz with a return loss of −18 dB. This antenna can be used for WLAN applications.

In this paper, a new defected ground structure is using to miniaturize microstrip patch antenna array for S-band at 2.45GHz. Initially, the novel structure of microstrip patch antenna designed at C-band resonates at 5.8GHz which operate in the Industrial Scientific Medical band (ISM). The proposed DGS is integrated in the ground plane of the patch antenna for size reduction. This structure has all favor to obtain a great gain and size reduction of microstrip patch antenna array. Finally, the resonance frequency of the novel structure of microstrip patch antenna shifts from 5.8GHz to 2.45GHz and with better performance miniaturization up to 85.53%. The antenna array presents a good performance in terms of gain 7.026dB and bandwidth 157.5MHz in the Industrial Scientific Medical band (ISM) centered at 2.45GHz. The design and simulation process is carried out by using two electromagnetic solvers CST-MW studio and HFSS.

A microstrip patch antenna using a defected ground structure (DGS) to suppress higher order harmonics is presented. An H-shaped defect on the ground plane with only one or more unit lattices has been utilized and yielded bandstop characteristics. Compared with a conventional microstrip patch antenna without the DGS unit cell, the radiated power of the DGS patch antenna at harmonic frequencies has been drastically decreased.

A new microstrip patch antenna that resonates on more than one frequencies and yields sufficiently high bandwidth is presented. Several variations of the proposed design are simulated using practically used dielectric materials. Detailed input return loss plots, VSWR plots, and radiation pattern plots are presented. A comparative study of all simulated results is presented. The design that yields the best performance is chosen for further optimization using deliberately-created defects in the ground plane, called Defected Ground Structures (DGS). It is observed that improvement in bandwidth is achievable through using the DGS.

A rectangular microstrip antenna (RMSA) designed for dual-band response using defected ground structure was reported. Configuration was tested on economical rate glass–epoxy substrate placed at 1.5 mm from ground plane. Two rectangular slots and an elliptical slot were introduced in ground structure which results in dual-band operation at 2400 MHz and 5800 MHz with gain of 4.3 dB and 7.4 dB, respectively. However, a clarification of resonant modes that is responsible for getting dual-band operation was not given in the reported work. In this paper, using resonance curve plot, return loss plots, and vector surface current distributions, detailed analysis is given explaining dual-band response of reported work. From the analysis done, it is observed that variations in dimensions of slots embedded on ground plane modify the various mode frequencies that results in dual-band response. The selection of feed and placements of all slots results in matched impedance at TM01 and TM20 modes of operation.

By embedding four radial slots in ground plane, enhanced performances of a probe-fed annular-ring patch antenna operated at the TM/sub 21/ mode for conical-pattem radiation have been obtained. The size reduction achieved for the proposed antenna is about 75%, compared with the corresponding conventional annular-ring patch antenna at a fixed operating frequency. Moreover, with the large lowering in the resonant frequency, the impedance bandwidth of the proposed antenna can greatly be increased by a factor of about 4.8. Also, the antenna gain measured is increased by about 3 dBi. Owing to these enhanced performances, the proposed antenna is suitable for present-day mobile communication. In addition, the design of adding a reflecting plate behind the antenna's ground plane to reduce the backward radiation due to the embedded slots in the ground plane is also studied.

An asymmetric defected ground structure (DGS) with respect to a microstrip line is proposed. Its unit cell consists of two square slots connected with a rectangular slot by meandered transverse slots. The simulated, measured and equivalent circuit responses have been presented. The unit DGS pattern under microstrip line produces wide rejection bandwidth and high sharpness factor. Its elliptic band-reject filter response is modelled by appropriate LC equivalent circuit. Two such DGS cells under a microstrip line produce 3-pole quasi-elliptic bandstop filter response, which shows deeper attenuation without appreciable change in pole frequencies in comparison to single cell structure. Unit DGS pattern under coupled gap microstrip lines produces band-accept filtering characteristics. The frequency characteristics show a quasi-elliptic highpass filtering characteristics with sharp lower transition knee. Accordingly, an LC equivalent circuit is proposed. A cascaded band-accept and band-reject filter is proposed for designing a wideband bandpass filter. The bandwidth and centre frequency of the bandpass filter can be varied by choosing different set of DGS dimensions.

A compact feed poly line slotted rectangular microstrip patch antenna with defected ground surface has been proposed in this paper for the wireless LANs, Bluetooth, and WiFi applications. The patch is designed based on a polyline slot and with defected ground structure. The simulated and fabricated models of demonstrated antenna exhibit better return loss, bandwidth, acceptable gain, and other antenna parameters over the required frequency range and the central frequency of 2.4 GHz is a worldwide free spectrum ISM band. The proposed antenna is fabricated using a highly sensitive PCB technique, and fabricated antenna parameters have been achieved compared to simulated results. The simulated and fabricated results conclude less than 3% error among them and owing to the proposed method, miniaturization of antenna achieved with a gain of 5 dB.

A comparative study to determine the most highly sensitive resonant frequency among the first four resonant frequencies of a conventional patch antenna and defected ground structure (DGS)-loaded patch antennas using commonly used DGS geometries in the literature, such as a rectangular slit, single-ring complementary split ring resonators (CSRRs) with different split positions, and double-ring CSRRs (DR-CSRRs) with different locations below the patch, for relative permittivity measurement of planar materials was conducted. The sensitivity performance for placing the DGS on two different locations, a center and a radiating edge of the patch, was also compared. Finally, the effect of scaling down the patch size of the DGS-loaded patch antenna was investigated in order to enhance the sensitivities of the higher order resonant frequencies. It was found that the second resonant frequency of the DR-CSRR DGS-loaded patch antenna aligned on a radiating edge with a half scaled-down patch size shows the highest sensitivity when varying the relative permittivity of the material under test from 1 to 10. In order to validate the simulated performance of the proposed antenna, the conventional and the proposed patch antennas were fabricated on 0.76-mm-thick RF-35 substrate, and they were used to measure their sensitivity when several standard dielectric substrate samples with dielectric constants ranging from 2.17 to 10.2 were loaded. The measured sensitivity of the second resonant frequency for the proposed DGS-loaded patch antenna was 4.91 to 7.72 times higher than the first resonant frequency of the conventional patch antenna, and the measured performance is also slightly better compared to the patch antenna loaded with a meander-line slot on the patch.

Over last few decades, wireless communication system has sought more attention and plays predominant role in different areas for human personal and commercial applications. Day by day, with advancements in technology, wireless gadgets got more compact due to microelectronics fabrication and integration techniques. So, such applications put great demand over new design specifications on antenna structures used in transmitter and receiver for radio wave communication. In wireless applications depending upon, frequency bands and bandwidth requirements numerous compact antenna structures are used with improved efficiency. Microstrip patch antennas are highly regarded due to its compact size, easy integration with microwave circuits. In study of patch antenna, Defected Ground structures gain popularity these days due to its various benefits to enhance antenna performance. This research article, provides extensive literature survey over use of Defected Ground Structures (DGS) in microstrip patch antenna with its design consequences. This article also explores the enhancement in antenna parameters with implementation of DGS’s. DGS concept is used in microstrip patch antenna and microwave engineering for performance improvement of these devices. DGS can be merged with other techniques to enhance antenna operational parameters like gain, bandwidth, VSWR and spurious radiations.