Defected Ground Structure Research Articles

Design of half circular wideband antenna for ship radar

The research aims to design a wideband antenna for the ship's radar. The ship's radar works on the S-Band range whose wavelengths range from 8 to 15 cm with a frequency of 2-4 GHz, This antenna design uses a new approach involving the use of Defected Ground Structure (DGS) and Defected Microstrip Structure (DMS), which builds on the initial theory. The results of the study obtained a bandwidth value of 1.6 GHz, an impedance antenna value of 49.7 ohms, with a total efficiency of -0.3356 a working frequency range ranging from 1.74 GHz to 3.3 GHz. The radiation pattern obtained the main lobe magnitude value of 3.85 dBi, Main lobe direction of 162.0 deg, angular width (3dB) of 76.7 deg, and side lobe level of -1.1 dB. From the results of working frequency, it is found that the antenna can be used for airborne warning & control (AWACS), remote sensing, WiFi, Bluetooth, mobile communication, XM radio, airport surveillance radar (ASR), radioastronomy, wireless LAN, ZigBee, missile guidance.

Hexagonal Microstrip Patch Antenna with Defective Ground Structure for Wideband Applications

The complexity and variety of modern wireless communication devices have resulted in an increase in the need for high-performance and wideband antennas. This research proposes an innovative approach for enhancing the bandwidth of hexagonal patch antennas using a microstrip line feed and the Defected Ground Structure (DGS) technology. The area of the hexagonal patch with defective ground structure wideband antenna is 32×24 mm2. The wideband ability and compact dimensions of the hexagonal patch antenna make it attractive. The DGS approach is used to change the resonant behavior of the antenna, resulting in a significant bandwidth enhancement. The simulation results demonstrate that combining DGS with the microstrip feed leads to significant enhancements in gain, radiation characteristics, and impedance bandwidth. The approach has potential for a range of wireless communication applications that demand wide performance in a compact antenna design.

Design and Fabrication of a 2-Port Multiple Antenna System for mmWave Application

The next-generation wireless communication technology heading towards the mmWave band requires multiple antenna systems to achieve high diversity, high data rates, and reliability. The design of multiple antenna systems is always associated with the problem of mutual coupling between antenna elements. In order to achieve better system performance, the mutual coupling between the elements has to be minimized. This work basically aims to minimize the mutual interaction among the antenna elements. A 2-port multiple antenna system is presented, with the defected ground structure as a decoupling technique, in order to minimize the mutual coupling. The single microstrip patch antenna is initially designed to operate at 24 GHz; later, it is transformed into a 2-port multiple antenna system. The transformed 2-port multiple antenna is loaded with the defective ground structure. The designed antenna system is fabricated, and practical measurements are carried out. The isolation achieved with defective ground structure through simulation is −27dB, and the practical measured value is −40dB. The 2-port multiple antenna system performance is assessed through the following metrics: Envelope Correlation Coefficient(ECC), Diversity Gain(DG), and Channel Capacity Loss(CCL). For the proposed 2-port multiple antenna the obtained values of ECC, DG and CLL are 0.004, 9.99dB and 0.4 bit/s/Hz. The results of the simulated structure are in good agreement with the fabricated structure. The result shows that defective ground is the better technique to achieve isolation between the closely placed antennas. The defective ground structure is the simplest technique in comparison with other techniques, such as metamaterial, energy band gap etc. The major novelty of the work includes, the design of a 2-port multiple antenna system with single slot and achieving the isolation more than −47dB without affecting the antenna resonating frequency.

Second- and Third-Harmonic Backscatter Through a Bandstop Filter Using Defected Ground Structure

In this brief, a novel harmonic-backscatter-rectifier (HBR) is introduced for simultaneous rectification and harmonic-based uplink. The proposed (HBR) employs a rectifier to generate both DC power and the harmonic carriers for backscattering communication, and a dual-band reconfigurable band-stop filter using defected ground structure (DGS) to modulate the second and third harmonics with low-power consumption and same input impedance at f0 all the time. As a proof of concept, an HBR prototype operating at 1.85 GHz was designed and experimented. An uplink data rate of 8 Mbps (4 Mbps × 2) was achieved when the HBR was fed with -10 dBm RF power, and the data modulation consumed less than 27.7 pJ/bit. In addition, a passive harmonic tag was implemented with the proposed HBR and a low-power binary sequence generator, which demonstrated a continuous uplink of 12 kbps at -6 dBm RF power.

A low loss microstrip line on thin flexible substrate film by defected ground structure

A low loss microstrip line on thin flexible substrate film by defected ground structure

High Isolation Wideband MIMO Antenna without Decoupling Technique for IoT Applications

This paper presents a method a high isolation wideband MIMO antenna without using any decoupling technique. This is achieved by transforming a strip line to a 1 ×2 MIMO antenna using Hilbert transform and Defected Ground structure is used in the antenna to resonate the antenna in for IOT and 5G sub-6 GHz bands. The proposed antenna has a size of 50 × 49.8 × 1.6 mm 3 and operates in the frequency band of 4.6 GHz to 5.94 GHz. The antenna simulated in ANSYS HFSS showed that its parameters Envelope correlation coefficient (ECC), Total Active Reflection Coefficient (TARC), Diversity gain (DG) and Channel Capacity Loss (CCL) are less than 0.04, -25 dB, 9.98 to 10 dB and less than 0.4 bits/s/Hz respectively. The radiation pattern of the antenna in both E-plane and H-plane has been simulated which the uniform distribution of power in the space.

Design of novel highly sensitive sensors for crack detection in metal surfaces: theoretical foundation and experimental validation

The application of different types of microwave resonators for sensing cracks in metallic structures has been subject of many studies. While most studies have been focused on improving the sensitivity of planar crack sensors, the theoretical foundation of the topic has not been treated in much detail. The major objective of this study is to perform an exhaustive study of the principles and theoretical foundations for crack sensing based on planar microwave resonators, especially defective ground structures (DGS) including complementary split ring resonators (CSRRs). The analysis is carried out from the equivalent circuit model as well as the electromagnetic (EM) field perspectives, and guidelines for the design of crack sensors with high sensitivity are developed. Numerical and experimental validation of the provided theoretical analysis is another aim of this article. With this aim, the developed guidelines are used to design a crack sensor based on a single-ring CSRR. It is shown that the sensitivity of the proposed sensor is almost three times higher than the sensitivity of a conventional double-ring CSRR. Moreover, it is demonstrated that folded dumbbell-shape DGS resonators can be used to achieve even higher sensitivities. The CSRR-based crack sensors presented in this study and other studies available in the literature are only sensitive to cracks with a specific orientation. To address this limitation, a modified version of the DGS is proposed to sense cracks with arbitrary orientations at the cost of lower sensitivity. The performance of all the presented sensors is validated through EM simulation, equivalent circuit model extraction, and measurement of the fabricated prototypes.

Wideband and Highly Selective BandPass Filter Using Substrate Integrated Waveguide Technology for Ku-Band Applications

A new compact design of bandpass filter using substrate integrated waveguide (SIW) is proposed and analyzed in this paper. It offers good in-band return loss, low insertion loss, wide passband, and high stopband attenuation. The filtering response is achieved by loading a couple of inverted tuning fork-shaped defected ground structures (DGS) on the bottom of the SIW cavity. DGS is utilized to enhance the upper stopband performance. To validate, the filter is fabricated using Rogers RT/Duroid 5880 with 0.508 mm thickness and tested. The filter has a center frequency of 15.44 GHz with 19% fractional bandwidth (FBW). The return loss is more than 20 dB and the insertion loss is about 1.2 dB. It finds its application in Ku band satellite communication.

A wideband, thin profile and enhanced gain microstrip patch antenna modified by novel mushroom-like EBG and periodic defected ground structures

This paper presents a wideband, thin-profile and enhanced-gain microstrip patch antenna improved by using a novel mushroom-like Electromagnetic Band Gap (EBG) structure and forming periodic Defected Ground Structures (DGS) on the ground plane. The proposed antenna operates between 9.56 and 14 GHz and has 4.44 GHz–10 dB impedance bandwidth. With A4, the gain of the reference antenna is increased by 64.4%, while a 38% bandwidth is also achieved. The parametric analyses carried out on the metallic part area of the novel EBG patch indicated that when the area of the used EBG patches are approximately three quarters or less of the conventional ones, greater gain values for the designed antenna are obtained. This relation between the EBG patches and the antenna gain can be pointed out as the novelty of the study. The results were analysed by the simulations carried out with CST Microwave Studio and were verified by measurements from manufactured prototypes.

Design and analysis of ultra-wideband four-port MIMO antenna with DGS as decoupling structure for THz applications

The growing demand for high-speed communication has resulted in developing terahertz (THz) antennas that operate at high-frequency, high-speed, and high data rates. An ultra-broadband functioning four port THz multiple input and multiple output (MIMO) antenna with a defective ground plane as a decoupling structure is proposed in this study. A rectangular metallic patch was changed by integrating parasitic components onto the radiator with the lowered ground plane on a polyamide substrate to obtain the ultra wideband THz frequency operating antenna. The designed THz antenna has been transformed into a MIMO antenna by replicating horizontally and vertically with the separation of 0.08 λ and 0.01 λ, respectively (λ computed at 2 THz). The proposed THz MIMO antenna operates in the 2–10.7 THz frequency range and has an overall substrate dimension of 40 μm x 46 μm × 2 μm. The proposed antenna equivalent circuit is designed to validate the impedance bandwidth of the antenna. The designed THz MIMO antenna has isolation better than 20 dB across the impedance bandwidth. The isolation enhancement is achieved by creating alternate current channels through the defected ground structure of the antenna. The proposed THz MIMO antenna's MIMO diversity features are studied and determined to be ECC < 0.001, DG is about 10 dB, TARC < -10 dB, MEG < -3 dB, and CCL < 0.2 bps/Hz over the antenna's operational frequency.

Design of 5G MIMO 2x2 Broadband Antenna At 26 GHz Frequency Using Double U-Slot Method and Defected Ground Structure

The 5G technology is a telecommunications innovation that offers incredibly high-speed data transfer. It is expected to outperform its predecessors significantly. In utilizing 5G services, efficient devices are crucial, and solutions like Multiple Input Multiple Output (MIMO) systems play a key role. MIMO is an antenna system with numerous transmitting and receiving elements, enabling simultaneous transmission and reception. A 26 GHz frequency microstrip antenna is modified using a double U-slot, and the Defected Ground Structure (DGS) method is employed to reduce antenna coupling effects and enhance bandwidth. This antenna features a directional radiation pattern that focuses in a specific direction, thereby increasing efficiency. Prior to optimization, the return loss was at around -14.15 dB, VSWR was approximately 1.49 dB, and bandwidth was 0.65 GHz. After optimization, the return loss improved to between -27.06 and -28.09 dB, signifying performance enhancement. Despite a slight increase in VSWR to 1.08 to 1.09 dB, it remains within acceptable limits. The bandwidth increased to 1.06 to 1.13 GHz. These results indicate that optimization successfully boosted antenna performance, resulting in higher data transfer efficiency. This technology has the potential to revolutionize the telecommunications landscape with faster and more reliable services through advanced 5G networks.

Quad Element MIMO Antenna for C, X, Ku, and Ka-Band Applications.

This article presents a quad-element MIMO antenna designed for multiband operation. The prototype of the design is fabricated and utilizes a vector network analyzer (VNA-AV3672D) to measure the S-parameters. The proposed antenna is capable of operating across three broad frequency bands: 3-15.5 GHz, encompassing the C band (4-8 GHz), X band (8-12.4 GHz), and a significant portion of the Ku band (12.4-15.5 GHz). Additionally, it covers two mm-wave bands, specifically 26.4-34.3 GHz and 36.1-48.9 GHz, which corresponds to 86% of the Ka-band (27-40 GHz). To enhance its performance, the design incorporates a partial ground plane and a top patch featuring a dual-sided reverse 3-stage stair and a straight stick symmetrically placed at the bottom. The introduction of a defected ground structure (DGS) on the ground plane serves to provide a wideband response. The DGS on the ground plane plays a crucial role in improving the electromagnetic interaction between the grounding surface and the top patch, contributing to the wideband characteristics of the antenna. The dimensions of the proposed MIMO antenna are 31.7 mm × 31.7 mm × 1.6 mm. Furthermore, the article delves into the assessment of various performance metrics related to antenna diversity, such as ECC, DG, TARC, MEG, CCL, and channel capacity, with corresponding values of 0.11, 8.87 dB, -6.6 dB, ±3 dB, 0.32 bits/sec/Hz, and 18.44 bits/sec/Hz, respectively. Additionally, the equivalent circuit analysis of the MIMO system is explored in the article. It's worth noting that the measured results exhibit a strong level of agreement with the simulated results, indicating the reliability of the proposed design. The MIMO antenna's ability to exhibit multiband response, good diversity performance, and consistent channel capacity across various frequency bands renders it highly suitable for integration into multi-band wireless devices. The developed MIMO system should be applicable on n77/n78/n79 5G NR (3.3-5 GHz); WLAN (4.9-5.725 GHz); Wi-Fi (5.15-5.85 GHz); LTE5537.5 (5.15-5.925 GHz); WiMAX (5.25-5.85 GHz); WLAN (5.725-5.875 GHz); long-distance radio telecommunication (4-8 GHz; C-band); satellite, radar, space communications and terrestrial broadband (8-12 GHz; X-band); and various satellite communications (27-40 GHz; Ka-band).

A novel defected ground structure for high-isolation circularly polarized MIMO patch antenna

ABSTRACT This paper introduces a method to reduce mutual coupling in a two-element multiple-input multiple-output (MIMO) antenna, which is a significant challenge due to the need for high isolation over a wide frequency range with close element spacing. Previous works typically achieved high isolation within a narrow bandwidth. The paper presents a novel defected ground structure (DGS) with a modified I-shaped slot, which effectively minimizes mutual coupling in a dual-sense MIMO circularly polarized (CP) antenna over a broader bandwidth than the previous approaches. The fabricated 2-element prototype with an overall size of 0.98λ × 0.71λ × 0.05λ and an edge-to-edge spacing of 0.08λ at the center operating frequency has a measured bandwidth of 2.5% (5.2–5.33 GHz). Across this band, the isolation is always better than 35 dB and the gain is higher than 4.8 dBi. The MIMO parameters are also investigated, which proves the good diversity performance of the proposed design.

Design and implementation of an efficient sierpinski carpet fractal antenna with defected ground structure for 2.45 GHZ applications

A sierpinski carpet fractal antenna with Defected Ground Structure (DGS) is unveiled. The fractal dimensions had paved the way for numerous applications. Fractal technique is applied to the patch and rectangular slot is made in the ground plane which acts as a DGS. The DGS disturbs the shield current and improves the performance of designed antenna. Dimension of designed antenna is 52 × 71 × 5.1 mm3. Rogers RO4350 substrate and coaxial feed technique are utilized in the design. The projected antenna is simulated and fabricated with the resonant frequency of 2.45 GHz. Commencing from the outcome of the projected antenna, it is evident that 23% wider Bandwidth, 13% increment in Gain, improved Return Loss of 15% and 26% VSWR are obtained compared to existing work. The measurements attained by fabricated antenna endow with excellent conformity to the simulated design.

Miniaturized and high gain circularly slotted 4×4 MIMO antenna with diversity performance analysis for 5G/Wi-Fi/WLAN wireless communication applications

A miniaturized with a high gain four port Multiple-Input Multiple-Output (MIMO) is presented in the manuscript. The presented design contains four radiating patch elements with a Defected Ground Structure (DGS). The shape of the radiating element is identified after the analysis of three stages. The design optimization is performed by changing the diameter of the circle loaded in the patch region and changing the length of the ground layer. The design is investigated for L, S, C, and X frequency band regions. The structure is designed using flame-retardant glass-reinforced epoxy laminate material (FR4) substrate material. The physical size of the four-port structure is 78x50 mm2. Three resonating frequency bands are observed at 2.02 GHz, 5.87 GHz and 11.19 GHz. The structure provides minimum return loss of −10.27 dB, −18.51 dB and −18.59 dB. The proposed design achieves a peak bandwidth of 3.94 GHz, and a maximum gain of 10.03 dBi, Various diversity parameters, including Total active reflection coefficient (TARC), Envelope Correlation Coefficient (ECC), mean effective gain (MEG), Diversity Gain (DG), and channel capacity loss (CCL), have been thoroughly analyzed. The measured and simulated outcomes are compared and analyzed. All performance indicators meet the allowed limits, demonstrating the suitability of the design for 5G, Wi-Fi and WLAN wireless communication applications.

High gain compact wearable antenna for IoT applications

In this paper, the design of a Defected Ground Structure (DGS)-based microstrip patch antenna tailored for sub-6 GHz 5G applications is reported. The proposed patch antenna is crafted using Jeans textile material. By integrating DGS into the traditional patch antenna design, we achieve a significant reduction in size while simultaneously enhancing the antenna’s performance. The antenna features a rectangular patch shape and is powered through a 50-ohm microstrip feed line. Boasting a compact size of 35.6 × 42.6 × 1.6 mm³, the antenna’s performance is further improved by incorporating DGS and etching slots on the patch. The expertly designed antenna yields a 34.87 dB return loss and a gain of 10.9 dB at a frequency of 3.5 GHz. The fabricated antenna demonstrates a robust impedance bandwidth within the range of 3.41–3.606 GHz. Consequently, the proposed antenna is well-suited for applications in WiMAX and IoT technologies.

A Compact Planar Ultra-Wideband Array Antenna

Ultra-wideband (UWB) antennas have recently gained prominence in communication, radar technology, and electronic warfare domains. The quick development of these antennas is due to the wide bandwidth requirements of pulse radar, ground penetrating radar, electromagnetic compatibility, spaceborne communication systems, stealth target detection, and more. Aiming to address the defects of existing UWB antennas, which often have narrow bandwidth and low gain, a planar ultra-wideband microstrip array antenna was designed to achieve good ultra-wideband characteristics and effectively improve the gain of the antenna. The initial bandwidth of the rectangular monopole antenna was 10 GHz–20 GHz. After loading multiple steps on the monopole patch, the bandwidth was increased to between 10 and 38 GHz. Using the new ultra-wideband array method that combines series feed and angle feed and the defective ground structure (DGS), the array maintains the ultrawide bandwidth span of 10–38 GHz of the array element, and the maximum gain of the antenna in the bandwidth was increased from 5.18 dBi to 9.55 dBi. The challenge of impedance matching of antenna units in ultra-wideband is resolved by the novel array technique, which also increases the antenna’s gain within the bandwidth. The antenna simulation is consistent with the measurement results. With its extensive operating frequency band, high gain, compactness, and favorable radiation attributes, this newly designed antenna holds significant promise for application in UWB radar systems.

Bidirectional circularly polarized antenna with defected ground structure for wideband operation

The present work proposes a wideband circularly polarized antenna with novel design to cover the operation over most of the X-band of the microwave frequencies. This antenna is planar and printed on very thin and flexible Rogers’ substrate of material RO3003 with thickness 0.13mm. The antenna structure can be viewed as composed of an elliptic open annular strip that works as the main radiator. Two symmetric parasitic elements of elliptic arc-shaped narrow strips are capacitively coupled to the elliptic strip radiator. The feeding line is coplanar waveguide with defected ground structure. The parasitic elements and the defects on the ground structures help to enhance the bandwidth of both impedance matching and circular polarization. The antenna is designed to produce bidirectional radiation patterns with opposite sense of circular polarization. The design stages to arrive at the final design of the proposed antenna are described in detail. The antenna is fabricated for experimental assessment showing high performance regarding the circular polarization, bandwidth, and efficiency. The proposed antenna has total dimensions of 30×40×0.13mm3. Both the simulation and experimental results show that the antenna impedance is matched to 50Ω over the frequency band 7.5-13.0(54%bandwidth) and the axial ratio is lower than 3 dB over the frequency band 8.85-12.35GHz(33 % bandwidth). It is shown that the antenna gain ranges from 4.5 to 5 dBi, the radiation efficiency is greater than 99 % and the total efficiency is greater than 91 % over the entire frequency band of the proposed antenna.

Design of compact low‐profile planar filtering antenna with enhanced suppression level

AbstractA compact low‐profile planar filtering antenna with an enhanced suppression level is presented in this paper. The presented antenna has a simple structure, consisting of an E‐shaped driving patch, a shorted parasitic patch, and a defected ground structure (DGS). The E‐shaped driving patch serves as an effective radiator and facilitates the filtering response. The shorted parasitic patch is horizontally arranged and coupled with the driving patch through the radiating edge. And a radiation null and an extra in‐band resonance can be generated, which would simultaneously broaden the impedance bandwidth and improve the suppression level. In addition, a DGS on the metalized ground plane is etched to introduce another radiation null, and the out‐of‐band suppression level would be significantly enhanced. The filtering antenna with a center frequency of 3 GHz was constructed and tested to verify its performance. The measured values, which indicate a bandwidth of 10% (2.85–3.15 GHz) and a peak realized gain of 5.2 dBi, are in agreement with the simulated values. The presented filtering antenna features a low profile of 0.016λ0, a compact antenna size of 0.16λ20, as well as an improved suppression level of more than 22 dB.

Three-Dimensional Printed mm-Wave Circularly Polarized Filtering Antenna With Flexible Design and Spurious Suppression

In this communication, a 3-D printed circularly polarized (CP) filtering antenna with spurious suppression for 5G mm-wave applications is presented. First, a composite resonator, serving as both the last-stage resonator of a waveguide filter and an aperture antenna, is utilized to realize a filtering linearly polarized (LP) antenna. The 4 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> -order electric cross-coupling topology is employed to generate two radiation nulls at both sides of the passband, enhancing the selectivity. Then, a polarizer is presented and placed in front of the LP antenna to obtain the CP radiation. The operating principles of the polarizer are analyzed in detail, which features flexible size and insensitivity to the original filtering response. To demonstrate the concept, three filtering CP antennas with different polarizer dimensions are designed, exhibiting similar responses. After that, to suppress spurious modes and extend the spurious-free region, the defected ground structures (DGSs) are introduced. Finally, all three CP antennas are fabricated using 3-D printing and tested. Measured results show that 10 dB return loss and 3 dB AR bandwidths for all antennas are about 7% and 9%, respectively.