Reduced Cross-Polarization Patch Antenna with Optimized Impedance Matching Using a Complimentary Split Ring Resonator and Slots as Defected Ground Structure

In this article, an effective feed line technique is used instead of DGS (Defected Ground Structure) and CSRR (Complimentary Split Ring Resonator) which are commonly used for achieving UWB (Ultra-Wideband Applications) responses. A classical antenna is designed for 2.4GHz frequency with a feedline of 180° electrical length. The resonance of proposed antenna responses as UWB and it has interesting current distributions through the patch antenna. This paper avoided all aspects of existing techniques which are proposed to achieve UWB.

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.

: 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.

Microstrip patch antenna is widely presented based on its advantages, especially for WiMAX wireless applications. Although, reducing the antenna size is a distinguished topic of antenna development, the antenna performance significantly drops for a small antenna. In this paper, two slots on a compact square ring and defected ground structure (DGS) are presented for bandwidth enhancement and radiation efficiency at 5.5 GHz. When the DGS and slots are embedded in the structure of the designed antenna, two major improvements are achieved. Enhanced impedance bandwidths with |S11|< −10 dB range from 5.041 to 5.88 GHz (15.25%) and the radiation efficiency of 80.8% by loading DGS over conventional patch antenna are achieved. Both antennas with/without DGS achieve good far-field radiation patterns within the operating frequency band at 5.5 GHz. CST microwave studio is used for simulating the design. The physical antenna layout is printed on FR4 substrate. The proposed configuration has a miniaturized size of 25 × 25 mm2. The fabricated antenna is tested to validate the proposed design. Thus results obtained from simulations and measurements show good agreement. The proposed prototype can be considered a suitable candidate for WiMAX wireless applications.

This paper presents an analysis and design of a novel planar antenna in corporation with fractal shaped defected ground structure (DGS) for wireless communication devoted to emergency management. The conventional ground plane can be replaced by a Fractal DGS ground plane to get size reduction, better efficiency and suppress surface-waves. The synthesis of proposed antenna is carried out by means of particle swarm optimization (PSO) to identify the geometrical descriptors of the structure. The representative results reveals that the proposed geometry exhibit better impedance matching and multiband characteristics in comparison to conventional planar antenna (without any defects). The analyses from simulations, numerical and experimental validations are reported in order to illustrate the effectiveness of varying scale factor that contributes 69.08% size reduction of ground plane.

This paper reports a novel compact dual band bandstop filter (DB-BSF) structure using triangular shaped defected ground structure (DGS) and split ring type defected microstrip line (DMS). The triangular shaped DGS and split ring type DMS are designed to ensure resonance at two frequencies. The proposed design represents the combination of DMS and DGS geometries analyzed by effective capacitance and effective inductance. An appropriate equivalent parallel LC circuit model has been developed for performance analysis of individual geometries. A prototype operating at 2.4 GHz and 5.86 GHz frequencies has been developed on Rogers RO4350B substrate for the demonstration of the effectiveness of the proposed design. A very good agreement between the simulated and measured results demonstrate the effectiveness of the proposed technique. The design is miniature, board size of $12 \times 12 mm ^{2}$, and achieves a performance significantly improves the performance metrics of the DGS based dual band bandstop filter reported so far.

In this paper, a circular microstrip patch antenna is designed at implantable medical devices (IMDs) bands. The antenna is modified with different techniques to reduce the dimension and enhance the performance. This paper focuses the comparative performance analysis of the circular patch, the circular planer inverted F-antenna (PIFA), the circular PIFA with meandered line, the circular PIFA with meandering and defected ground structure (DGS), the multiple substrates layer circular PIFA with meandering, and finally the multiple substrates layer circular PIFA with meandering and DGS. These approaches provide the size reduction, gain enhancement, bandwidth broadening, and efficiency increment. Although this circular patch antenna offers large bandwidth, gain, and radiation efficiency; however the dimension of the antenna is quite high. The dimension of an antenna can be minimized by using circular patch PIFA. To reduce the overall size of this antenna, a circular meandering PIFA has been utilized. The circular meandering PIFA with DGS further increases the current conduction path and controls the input impedance. The increased current flow path contributes to the radiation efficiency. Moreover, the multiple substrates layer circular meandering PIFA helps to enhance the bandwidth, radiation efficiency, and frequency. The radiation efficiency can be increased more by inserting a DGS in the multiple substrates layer circular meandering PIFA.

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.

A novel approach to suppress mutual coupling (MC) between two patch antennas is presented in this letter. A parasitic isolator, which is printed between the two patches, controls the polarization of the coupling field to reduce the antenna coupling. Furthermore, a defected ground structure is employed to suppress the cross-polarization (XP) level. There exists a tradeoff between the MC reduction and XP improvement in this approach. As an example, a two-element patch array with an optimized isolator is fabricated and measured. The measured results show that, at the resonant frequency, the achieved isolation enhancement and XP level are 19.6 dB and $-$ 13.2 dB, respectively.

With the introduction of 5G, the future wireless communication technology, there is a need for higher bandwidth and data rate. As the major component frequency is moving towards mm-Wave, the RF component size decreases drastically. The antenna is the major component at the interface of free space and device, which also reduces in size drastically with the increase in the operating frequency. To achieve high gain and high data rate, MIMO stands promising. With the introduction of a large number of closely spaced antennas at the transmitter and receiver, the effects of mutual coupling increase. In this paper, a 2x2 MIMO is designed, with each antenna operating at 28GHz. Mutual coupling analysis of 2x2 MIMO antenna with the complete ground and by introducing defected ground structures. The mutual coupling analysis is carried out using the ECC and diversity through s-parameters, by varying the spacing between the two-antennas from λ/2 to λ/8 with and without Defected Ground Structures, where λ is the free-space wavelength. The DGS (Defected Ground Structures) used is dumbbell-shaped with a rectangular head introduced in the ground plane. Obtained results show that with the introduction of DGS structure radiating elements can be placed at a distance of λ/8 between them which in turn reduces the overall size of antenna systems. For wavelength λ/8 its S <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</inf> , S <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</inf> , VSWR (V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</inf> and V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> ) and Gain respectively are -18.77, -15.137, 1.260, 1.262 and 7.277 dBi.

This work presents a compact dual‐band patch antenna designed for skin implant applications. The antenna features a robot‐shaped patch structure on FR‐4 substrate and resonates at dual bands of 915 and 2430 MHz. Three techniques are employed to miniaturize the antenna: a shorting pin between the patch and ground, defected ground structure (DGS), and utilization of tissue electrical properties. Thus, the optimized antenna volume is found to be 8 × 12 × 1.36 mm 3 , with near‐perfect impedance matching. The antenna also achieves enhanced impedance bandwidths of 15.74% and 15.64% and gains of −29 and −16.6 dBi at 915 and 2430 MHz, respectively. Its specific absorption rates (SARs) are found to be acceptable, with values of 448 and 221 W/kg in the 1 g tissue standard at the respective bands. Furthermore, the antenna can communicate with the receiver antenna at a high data rate of 1 Mbps over 8–12 m, where the distance can be extended to 25–40 m by choosing a low data rate of 100 Kbps. The antenna is measured for its return loss ex vivo using chicken tissue, which is found to be in close agreement with the simulation results. Thus, the balanced performance in terms of compact size, large bandwidth, and comparable gain and SAR makes the proposed antenna a promising candidate for practical applications.

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 novel ultra wideband (UWB) bandpass filter (BPF) with a notch-band at specified frequency. Moreover, its equivalent circuit model (ECM) is also investigated. The proposed filter consists of a stepped impedance resonator (SIR), a parallel coupled feed line on the top and a rectangular shaped defected ground structure (DGS) on the bottom of the structure. The notch band can be shifted to any other desired frequency by tuning the length of the parallel coupled feed line. Good performances in terms of wide stop-band rejection, low insertion loss, high return loss and more compact size (7.99 × 6 mm2) than those reported in literature are achieved. In addition, simulation results accomplished by ECM are in good agreement with the full-wave EM.

In this paper a study on reduction of mutual coupling of two element microstrip antenna array with rectangular split ring shaped defected ground structure(DGS) is presented. The proposed DGS antenna is simulated by MOM based IE3D simulation software. An observation is made on S12 by changing the dimension of the defects and distance between the antenna array elements. The proposed antenna has a maximum 13.54 dB reduction of mutual coupling while dimension of DGS and distance between antenna elements are properly optimized. This antenna array is operated at 2.4 GHz with a gain of 7.01 dBi in the broadside direction.