Compact Frequency-Reconfigurable Slot Patch Antenna with Gain Enhancement via Metasurface Integration

May 5, 2025

Journal Optik

publisher Multidisciplinary Digital Publishing Institute

DOI https://doi.org/10.1016/j.ijleo.2025.172389

Issue 8

Volume 333

This work presents a frequency-reconfigurable slot antenna (FRSA) design that features a rectangular patch with a longitudinal slot on the ground plane, connected to eight vertical slots for basing. The proposed FRSA includes seven ideal switches (labeled w1–w7) positioned along the longitudinal slot, facilitating its reconfigurable functionality. By toggling these switches ON and OFF, the antenna operates in nine different modes. A single-layer metasurface reflector (MSR) was integrated below the FRSA to enhance the antenna's gain and directivity. The proposed MSR consists of a 2 ×2 array with a unit cell (UC) size of 18.25 mm×15.025 mm, optimized to produce a center-operating frequency. The MSR achieves a stopband transmission coefficient (S21) below −10 dB and exhibits a linear reflection phase within the bandwidth of 3.30 ─ 5.96 GHz, nearly encompasses the FRSA frequency tuning range 3.05 – 5.16 GHz. Combining the FRSA and MSR significantly enhanced performance. The gain improved by 2.49 dB overall, rising from 3.14 dB to 5.63 dB in the lower band and from 5.25 dB to 5.38 dB in the upper band. Varying the FRSA and MSR gap enabled more gain optimization, enabling the gain to range from 3.93 dB to 6.09 dB. The FRSA with MSR covers an operating frequency range of 3.05 GHz to 5.24 GHz and supports operation at 3.05 GHz, 3.38 GHz, 3.98 GHz, 4.06 GHz, 4.34 GHz, 4.70 GHz, 4.74 GHz, 4.80 GHz, and 5.24 GHz. The proposed FRSA with MSR maintains a compact configuration, as the MSR's size matches the antenna's dimensions (0.38 λ₀ × 0.31 λ₀). The gap between the MSR and the antenna is only 20 mm (0.204 λ₀), where the wavelength (λ₀) corresponds to the minimum operating frequency of 3.05 GHz in free space. A prototype of the FRSA with MSR was fabricated and its performance was validated through measurements. The proposed antenna is well-suited for applications of S-band, C-band, and cognitive radio technologies.

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Graphene-Based Frequency Reconfigurable Slot Antenna for Terahertz Applications

Apr 17, 2025

Journal Optik

publisher Elsevier GmbH

DOI 10.4304/jnw.8.7.1465-1469

This research presents the design of a multi-band frequency reconfigurable slot antenna (FRSA) that utilizes graphene in the terahertz (THz) regime. The proposed FRSA supports independent switching across twenty-nine operating bands: 0.518, 0.532, 0.56, 0.59, 0.636, 0.648, 0.66, 0.682, 0.724, 0.752, 0.758, 0.84, 0.938, 0.906, 1.166, 1.252, 1.256, 1.26, 1.304, 1.324, 1.336, 1.344, 1.532, 1.648, 1.70, 1.784, 1.95, 2.01, and 2.064 THz. The design features a rectangular patch with both vertical and longitudinal slots and incorporates seven graphene switches (labeled d1–d7) placed along these slots. These switches enable reconfigurability by controlling the surface conductivity of the graphene. The tunable properties of graphene present significant potential for developing smaller, reconfigurable antennas in THz wireless systems. The proposed FRSA features a compact design with dimensions of 268 µm x 240 µm x 10 µm, or 0.46 λ₀ × 0.41 λ₀ × 0.017 λ₀, where λ₀ represents the wavelength corresponding to the lowest operating frequency of 0.518 THz in free space. The patch structure is mounted on a 10 μm thick substrate made of Rogers RO3003 (with εr = 3 and tanδ = 0.001). The surface conductivity of graphene sheets is adjustable by applying a bias voltage, which influences the chemical potential of the graphene. The FRSA operates in ten states (S1–S10), determined by the ON and OFF positions of the graphene sheets. An analysis of the antenna performance was conducted, examining the reflection coefficient, and gain at various chemical potentials. This switching capability enables secondary users to access unused frequency bands, making the antenna suitable for cognitive radio applications. Furthermore, this technology can be applied in medical settings, as the antenna can assist in identifying skin conditions and cancerous tissues. Switching between different frequencies can improve imaging quality and capture various data types about the body being examined.

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Equivalent Circuit Model of Antenna Array Utilizing an Archimedean Spiral Sequential Feed Network for C-Band Applications

Jun 23, 2024

Journal Progress In Electromagnetics Research B (PEIR B)

publisher Wydawnictwo SIGMA-NOT Sp. z o.o. (SIGMA-NOT Publishing House Ltd.)

DOI 10.2528/PIERB24041403

Volume 106

This paper introduces the configuration of a microstrip antenna array with a new Archimedean spiral sequential feed network (SSFN) for the upper half of the C-band application. The Archimedean SSFN mechanism uses four circular patch elements to structure the proposed antenna array. The optimized reflection loss (S11) of the proposed SSFN mechanism was obtained by tuning the dimensions of each transformer and then connected with an antenna array. Aiming to make the suggested antenna array compact in size, bending feed lines were utilized. The antenna array is designed with overall physical dimensions of 75 mm × 75 mm × 1.575 mm, with an electrical size of 1.85λo mm, 1.85λo mm, 0.038λo at a frequency of 7.43 GHz. An equivalent circuit model (ECM) is designed and analyzed to verify the proposed Archimedean SSFN and the designed antenna array. Reflection losses of SSFN and microstrip spiral antenna array (SAA) were confirmed with the suggested circuit model utilizing Computer Simulation Technology (CST) Microwave Studio and Applied Wave Research (AWR) Microwave Office software. According to the empirical results, the SAA has a reflection loss bandwidth of 2.08 GHz (6.15-8.23 GHz) and a maximum gain of 10.2 dBi at 7.43 GHz. The axial ratio (AR) of the proposed antenna covers a bandwidth of 1.6 GHz (6.2-7.8 GHz), which is approximately 22.85% of the entire bandwidth. These results demonstrate a perfect agreement between the simulated and measured outcomes, making the suggested SAA suitable for the C-band wireless application.

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Broadband circular polarised printed antennas for indoor wireless communication systems: A comprehensive review

Jun 30, 2022

Journal Micromachines

publisher MDPI (Switzerland)

DOI https://doi.org/10.3390/mi13071048

Issue 7

Volume 13

With the rapid changes in wireless communication systems, indoor wireless communication(IWC) technology has undergone tremendous development. Antennas are crucial components ofIWC systems that transmit and receive signals within indoor environments. Thus, the developmentof indoor technology is highly dependent on the development of indoor antennas. However, indoorenvironments with limited space require the fewest indoor antenna units and the smallest indoorantenna sizes possible. Hence, indoor antennas with compact size and broad applications havebecome widely preferred. In an IWC system, circularly polarised (CP) antennas are generallyimportant, especially in dense indoor environments, because compared with linearly polarised(LP) antennas, CP antennas reduce polarisation mismatch and multipath losses. This paper combsthrough the existing studies related to three-dimensional (3D) geometry (nonplanar) or waveguideindoor antennas and the two common approaches to two-dimensional (2D) geometry (planar) indoorantennas, namely, broadband CP printed monopole antennas (BCPPMAs) and broadband CP printedslot antennas (BCPPSAs). The advantages, disadvantages and limitations of previous works arehighlighted as well. These research works are summarised, compared and analysed to understand therecent specifications of BCPPMAs and BCPPSAs to generate the most appropriate design structuresuitable for current IWC systems.

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A miniaturised UWB FSS with Stop-band Characteristics for EM Shielding Applications

Aug 1, 2021

Journal PRZEGLĄD ELEKTROTECHNICZNY

publisher Association of Polish Electrical Engineers - Stowarzyszenie Elektryków Polskich, SEP

DOI doi:10.15199/48.2021.08.25

Issue 8

Volume 97

This paper aims to present a miniaturised and new design of ultra-wideband (UWB) frequency selective surface (FSS) with stopband characteristics for electromagnetic (EM) shielding applications. The modelled FSS used the integration of a two parallel conductive metallic patch with a circular loop structure. The FSS provided a UWB stopband filter response covering a bandwidth of 10.5 GHz, for frequencies from 2.2 GHz to 12.7 GHz. The proposed FSS had a compact physical dimension of 5 mm × 5 mm × 1.6 mm, with a printed array of 19 × 19 FSS unit cells. An equivalent circuit configuration (ECC) was used to verify the FSS unit cell structure’s performance. The proposed FSS was identified to contribute towards independent polarisation for obliques incidences transverse electric (TE) and transverse magnetic (TM) polarisations from 0° to 20°. Besides, the performance of the proposed FSS is stable over a wide range of incident angles for TE and TM polarisations.

Frequency Reconfigurable Microstrip Antenna Array Based on Reconfigurable Defected Ground Structure

Aug 1, 2021

Journal PRZEGLĄD ELEKTROTECHNICZNY

publisher Wydawnictwo SIGMA-NOT Sp. z o.o. (SIGMA-NOT Publishing House Ltd.)

DOI 10.15199/48.2021.08.20

Issue 2021

Volume 8

In this article, a frequency-reconfigurable microstrip antenna array based on a defected ground structure is presented for C-band applications. The proposed antenna used the integration of two patches and the feeding network attached with a circular defected ground structure. The reconfigurable feature of the proposed antenna array is realized using a single switch inserted on the circular defected ground structure to modify the current distribution on the ground plane, which changes the resonance frequency. By switching the switch OFF, the antenna array eligible to resonate at two states and thus array centered at 4.83 and 5.36 GHz simultaneously. While switching ON, the antenna array eligible resonates at three states, and then the antenna array centered at 5, 5.52, and 5.90 GHz simultaneously. Furthermore, design steps, impedance bandwidth, and radiation patterns are introduced for the description and analysis of this antenna array. The finalized antenna array is simulated, manufactured, and measured successfully.

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Pattern reconfigurable planar antenna array based on two circular defected ground structure

Jul 1, 2021

Journal PRZEGLĄD ELEKTROTECHNICZNY

publisher Wydawnictwo SIGMA-NOT Sp. z o.o. (SIGMA-NOT Publishing House Ltd.)

DOI 10.15199/48.2021.07.10

Issue 7

Volume 2021

A pattern-reconfigurable dual-element microstrip antenna array based on reconfigurable two circular defected ground structures was proposed. Five switches are embedded in the two circular defected ground structures to tune the beam orientation. The proposed design is able to work in two modes by selecting various combinations of the switch states. The proposed array was fabricated on a Roger board and prepared to shift the beam orientations at the working frequency of 7 GHz. Finally, one prototype of the antenna array was fabricated and tested. The simulated results illustrate that the beam steered 52° while the measured beam steered 37.

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Circuit Model for Microstrip Array Antenna with Defected Ground Structures for Mutual Coupling Reduction and Beamforming Applications

Jan 30, 2021

Journal INTERNATIONAL JOURNAL OF INTEGRATED ENGINEERING

publisher Association of Polish Electrical Engineers - Stowarzyszenie Elektryków Polskich, SEP

DOI doi.org/10.30880/ijie.2021.13.01.010

Issue 1

Volume 13

A microstrip array antenna (MAA) structure incorporated with an orthogonal I-shaped defected ground structure(OI-DGS) was proposed and investigated and its equivalent circuit was created. Reflection losses were simulated and verified with the proposed circuit model using CST Commercial and AWR Microwave Office software. The optimized S11 parameter of the model was obtained by tuning the dimensions of the microstrip patch elements in the MAA and the lengths and widths of the slots of defected ground structure (DGS). The proposed equivalent circuit is expected to be useful as a model for the DGS design and to study its behavior. Finally, two prototypes of MAA, without and with OI-DGS, were fabricated by the milling technology and tested. The simulated results showed that -5.53 dB mutual coupling reduction and the measured around -3 dB. The simulated results demonstrate that main beam shifted 43° while the measured main beam shifted 36°

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Microstrip antenna array with defected ground structure and copper tracks for bandwidth enhancement

Dec 22, 2020

publisher Association of Polish Electrical Engineers - Stowarzyszenie Elektryków Polskich, SEP

A dual-element microstrip antenna array with two circles defected ground structure, and two copper tracks are proposed for the bandwidth enhancement. Bandwidth enhancement achieved with the introduction of dual circular slots defected ground structure. Furthermore, two copper tracks are integrated into one of the circles' defected ground structure to reduce the input impedance, producing more bandwidth enhancement of the antenna array. Parametric analysis of the proposed antenna array investigated for the investigation of bandwidth enhancement. The proposed antenna array generates a simulated impedance bandwidth of 1.52 GHz from 6.03 to 7.55 GHz, with an acceptable far-field radiation pattern achieved within the operating band.

DEFECTED GROUND STRUCTURE FOR BEAM STEERING ARRAY ANTENNA APPLICATIONS

Oct 1, 2015

Journal ARPNJournal of Engineering and Applied Sciences

publisher Association of Polish Electrical Engineers - Stowarzyszenie Elektryków Polskich, SEP

Issue 19

Volume 10

Incorporation of Defected Ground Structure (DGS) into the Microstrip Phased Array Antenna (PAA) provides desirable changes to the direction of the main beam. In this paper, an investigation on the development of 2 x 1rectangular patches that operate at 9 GHz is presented. The two rectangular patches are separated at 0.258 and the microstrip line is feeding to the center of the patches to provide impedance matching. Then, an orthogonal-I-shaped DGS is inserted in between the two patches at the ground plane. It is found that by changing the dimension of the DGS, the main lobe of the PAA increases from 39 to 137, however, the directivity of the arrays maintains about 6 dBi. This demonstrates the potential of employing DGS to steer the main beam of PAA instead of using additional phase shifter which is bulky and more complicated to connected to the antenna’s feeding line.

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Miniaturized Hybrid Rat-Race Coupler of a 2.5 GHz Loaded by Resistors

Jan 7, 2013

Journal Journal of Networks

publisher Academy Publisher

DOI :10.4304/jnw.8.7.1465-1469

Issue 7

Volume 8

A rat-race coupler is one of the essential components used in microwave circuits Rat-race coupler has numerous applications in satellite communication, phased array radar antenna systems and radar Recently, wireless communication systems usually require smaller device size, in order to meet circuit miniaturization Thus, size reduction becoming major design considerations for practical applications This paper includes design the proposed microstrip rat-race coupler for frequency 25 GHz The area of the proposed rat-race coupler compared with the conventional structure, the proposed rat-race coupler in this paper has smaller size than the conventional structure The main outcome of this work is reducing the area of the proposed coupler by 10% Microwave Office (MWO-225-SUF) tool is used to execute the design of the coupler in this work.

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Frequency Reconfigurable Array Antenna with Modified Circular Slot

Dec 19, 2022 - Dec 21, 2022

Publisher IEEE

DOI 10.1109/RFM56185.2022.10064819

Country Malaysia

Location Kuala Lumpur

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Microstrip Antenna Array with Defected Ground Structure and Copper Tracks for Bandwidth Enhancement

Dec 14, 2020 - Dec 16, 2020

Publisher 2020 IEEE International RF and Microwave Conference (RFM)

DOI 10.1109/RFM50841.2020.9344781

Country Malaysia

Location Kuala Lumpur, Malaysia

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A Dual-Band Frequency Reconfigurable Antenna Array Based on Reconfigurable Defected Ground Structure

Dec 14, 2020 - Dec 16, 2020

Publisher IEEE

DOI 10.1109/RFM50841.2020.9344790

Country Malaysia

Location Kuala Lumpur

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Dual microstrip antenna patches with orthogonal i-shaped defected ground structure for beam steering realization

Dec 11, 2016 - Dec 13, 2016

Publisher IEEE AP/MTT/EMC Joint Chapter of Malaysia

DOI 10.1109/APACE.2016.7915880

Country Malaysia

Location Kedah

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Beam Steering of Array Antenna with 2-Orthogonal-I-Shaped Defected Ground Structure

Dec 11, 2016 - Dec 13, 2016

Publisher IEEE

DOI 978-1-5090-1060-8/16/$31.00 ©2016 IEEE

Country Malaysia

Location Kedah