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This research presents an innovative dual-band microstrip patch antenna design enhanced with defected ground structures (DGS) and barium strontium titanate (BST) thin film, tailored for wireless local area network (WLAN) and WiMax applications. The first design phase involved the development of an microstrip patch antenna (MPA) using an flame retardant (FR4) substrate with a permittivity (er1) of 4.3 and a thickness of 1.524 mm, enhanced with DGS. This configuration achieved a single-band resonance at 4.1 GHz, with a bandwidth of 0.82 GHz and a return loss (S11) of -32 dB. The second phase involved the integration of a BST thin film, with a high permittivity(er2) of 250 and a thickness of 0.1 mm, into the DGS-enhanced microstrip patch antenna (MPA). This modification led to a transformation in the antenna's performance, enabling dual-band operation at resonance frequencies of 2.8 GHz and 5.8 GHz. Further, there was a corresponding substantial increase in bandwidth to 1.34 GHz and 1.25 GHz, respectively, an improvement in S11 values to -16.3 dB and -21.4 dB. Moreover, and antenna's size of 14×10×1.524 mm³. The study underscores the critical role of innovative material use and design optimization in advancing antenna technology, offering significant enhancements in bandwidth, and miniaturization, for wireless communication systems. [ABSTRACT FROM AUTHOR]

A novel miniature wideband rectangular ring antenna is proposed for 4.6–6.2 GHz which is compatible with IoT applications. The wideband response of the proposed antenna is achieved by a partial ground and stair step structure. Because modifying the width and etching the ground plane does not improve the impedance matching over a large bandwidth, a triangular shape DGS is inserted in the partial ground plane to increase the antenna bandwidth with enhanced return loss. The wideband features of the antenna were explored here by incorporating different DGS shapes such as triangles, rectangle, pentagon, circle, and oval in the partial ground. The results have been successfully verified through measurement. The simulated fractional bandwidth is greater than 29% at 4.6–6.2 GHz whereas the measured fractional bandwidth is 27.6% at 4.75–6.2 GHz. In both cases, the maximum return loss is greater than 55 dB. The gain of the antenna is greater than 2.6 dB with good efficiency and nearly omnidirectional radiation pattern in shape. Due to its compact size and outstanding performance, the suggested stair step-shaped rectangular ring antenna could be a promising choice for IoT and wireless applications. [ABSTRACT FROM AUTHOR]

A two‐port planar dual circularly polarised microstrip patch antenna is presented. The designed antenna has two groups of patches, each for transmission and reception. In one such group, only the central patch with truncated opposite corners is probe‐fed whereas the surrounding patches act as parasitic patches for bandwidth and gain enhancement. A defected ground structure (DGS) consisting 4 units of complementary square spiral resonators is used to enhance the port‐to‐port isolation as well as the axial ratio (AR) bandwidth. Based on the measured data of the fabricated prototype, the antenna is seen to have an impedance bandwidth of 900 MHz with the centre frequency of f0=6.40GHz. Moreover, the AR bandwidth is measured to be 600 MHz at fAR=6.36GHz, whereas the peak gain within this band is found to be ranging from 6.8 to 7.9 dBic. It is also noted that the AR bandwidth lies entirely within the impedance bandwidth and the cross‐polarisation discrimination is 20 dB in the boresight direction. [ABSTRACT FROM AUTHOR]

In this paper, new designs of optically transparent wearable antennas have been presented. The explored antennas have the excellent features of high flexibility, small size, low specific absorption rate (SAR) and high optical transparency. The proposed antennas are realised by utilising highly flexible, optically transparent and low‐cost materials. For achieving compactness in antenna dimension and for improved transparency, square‐ring‐shaped radiator is used in the antenna design. To improve the efficiency and gain of the square‐ring patch antennas, a new technique is proposed in this paper. The proposed technique utilises a strip line that connects the middle of the two opposite sides of the ring. Full ground plane is used in antenna design to reduce the back radiation. However, full ground plane reduces optical transparency. To elevate optical transparency without affecting antenna's back radiation significantly, a new technique of defected ground structure is investigated in this study. With this defected ground structure, the optical transparency is improved by about 6% without significantly compromising the SAR. The compatibility of the proposed antennas for wearable applications are investigated by examining the performances on flat and bent phantoms. Moreover, the robustness of the antennas are studied by subjecting the prototypes to multiple bending operations. [ABSTRACT FROM AUTHOR]

This study presents a new slitted electromagnetic bandgap (EBG) structure to filter undesired wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) bands in the ultra‐wideband (UWB) spectrum. A simple UWB antenna which consists of a microstrip tapered feed line, a circular patch and a defected ground structure is used as a reference antenna. The antenna is then integrated with a slitted EBG structure near the feed line to notch two interfering bands. The created notched bands by the EBG structure can be independently controlled. Owing to structural symmetry of the proposed antenna, the size can be reduced by approximately half to form a miniaturised antenna. The miniaturised antenna has the same full‐size antenna characteristics with little change in the notched bands specifications. Frequency domain measurement results show that the full‐size and miniaturised antennas have a flat transfer function, and a group delay variation of about 0.5 ns in the entire UWB band except for the notched bands. [ABSTRACT FROM AUTHOR]

In this article, the radiation characteristics of the microstrip patch antenna with periodic defected ground structures have been studied. These structures are realized by etching off defected patterns from the ground plane of planar circuits and antennas. Results indicate that a periodic defected ground structure has good effect on reducing the patch resonant length without decreasing the impedance bandwidth. [ABSTRACT FROM AUTHOR]

This Letter presents a novel H‐shaped conducting wall structure that effectively suppresses the mutual coupling between two closely spaced microstrip antennas (MSAs). The wall consists of an H‐shaped copper strip printed on a dielectric substrate, and a row of periodic vias through which the strip is connected to a ground plane. The wall is inserted between the MSAs and surrounds half the periphery of each antenna. Measurements of a prototype show that the high isolation of about 51 dB is achieved between two MSAs separated by the edge‐to‐edge distance of 0.052 λ0 at 5.2 GHz. The proposed structure greatly improves the isolation without causing any significant degradation of the antenna bandwidth, gain, or front‐to‐back ratio, unlike other isolation structures based on resonators or defected ground structures. [ABSTRACT FROM AUTHOR]

A printed ultra‐wideband (UWB) antenna with five notched stop bands is presented. By introducing a pair of arc‐shaped slots, two defected ground structures and an open‐loop resonator, five sharp notches are achieved at frequencies of 2.4, 3.2, 5.2, 5.8 and 7.5 GHz. The proposed antenna has been fabricated and tested. The measured results indicate that the proposed design not only supports UWB bandwidth requirements but rejects five narrow bands to avoid possible interference with existing communication systems. In addition, the proposed antenna has relatively omnidirectional radiation patterns in passbands. [ABSTRACT FROM AUTHOR]