This paper demonstrates the performance of a potential design of a paper substrate-based flexible antenna for intrabody telemedicine systems in the 2.4 GHz industrial, scientific, and medical radio (ISM) bands. The antenna was fabricated using 0.54 mm thick flexible photo paper and 0.03 mm copper strips as radiating elements. Design and performance analyses of the antenna were performed using Computer Simulation Technology (CST) Microwave Studio software. The antenna performances were investigated based on the reflection coefficient in normal and bent conditions. The total dimensions of the proposed antenna are 40 × 35 × 0.6 mm³. The antenna operates at 2.33–2.53 GHz in the normal condition. More than an 8% fractional bandwidth is expressed by the antenna. Computational analysis was performed at different flexible curvatures by bending the antenna. The minimum fractional bandwidth deviation is 5.04% and the maximum is 24.97%. Moreover, it was mounted on a homogeneous phantom muscle and a four-layer human tissue phantom. Up to a 70% radiation efficiency with a 2 dB gain was achieved by the antenna. Finally, the performance of the antenna with a homogeneous phantom muscle was measured and found reliable for wearable telemedicine applications.

A compact ultrawideband (UWB) antenna based on a hexagonal split-ring resonator (HSRR) is presented in this paper for sensing the pH factor. The modified HSRR is a new concept regarding the conventional square split-ring resonator (SSRR). Two HSRRs are interconnected with a strip line and a split in one HSRR is introduced to increase the electrical length and coupling effect. The presented UWB antenna consists of three unit cells on top of the radiating patch element. This combination of UWB antenna and HSRR gives double-negative characteristics which increase the sensitivity of the UWB antenna for the pH sensor. The proposed ultrawideband antenna metamaterial sensor was designed and fabricated on FR-4 substrate. The electrical length of the proposed metamaterial antenna sensor is 0.238 × 0.194 × 0.016 λ, where λ is the lowest frequency of 3 GHz. The fractional bandwidth and bandwidth dimension ratio were achieved with the metamaterial-inspired antenna as 146.91% and 3183.05, respectively. The operating frequency of this antenna sensor covers the bandwidth of 17 GHz, starting from 3 to 20 GHz with a realized gain of 3.88 dB. The proposed HSRR-based ultrawideband antenna sensor is found to reach high gain and bandwidth while maintaining the smallest electrical size, a highly desired property for pH-sensing applications.

In this work, we present a shared aperture (SA), dual-band in metal-rim antenna system targeting the sub-6GHz and millimeter-wave (mm-wave) bands of the 5G wireless standard. The antenna system consists of a SA cactus-shaped slot engraved on the side of standard mobile terminal rim that hosts a microwave radiating structure covering the sub-6 GHz bands as well as a 4-element slot based connected antenna array (SB-CAA) covering the mm-wave bands. This provides a compact sized solution for multiband operation within these bands. The CAA has beam forming capabilities where the beam can be steered between +/− 30 degrees with acceptable gain and side lobe levels (SLL). A single 4-element slot based in-rim SB-CAA is also proposed that covered more than 6 GHz of frequency bandwidth (25.5–32 GHz) with a total efficiency exceeding 85% and realized averaged gain of 8.2 dBi over the bands covered. The SA cactus antenna structure had a bandwidth exceeding 3.5 GHz with total efficiency exceeding 75% and an average realized gain of 8 dBi between 26.5 – 30 GHz. For the microwave band covered (3.45-3.56 GHz) by this SA cactus antenna, a bandwidth of 140 MHz, efficiency of 90% with 2.5 dBi of measured gain were achieved.

A miniatured NRI metamaterial comprised of meander line and elliptical split ring resonator is presented in this paper, offering a negative refractive index with small unit to wavelength ratio. The meander line technique miniatures the cell size, where the elliptical split ring resonator give the desired permeability. It has two double negative regime one is from 2.46 to 3.31 GHz (bandwidth of 850 MHz) and another one is from 3.85 to 4 GHz (bandwidth of 150 MHz). An effective medium ratio of 12.86, implies the novelty of the proposed design for S-band applications. The electrical length of the structure is 0.06λ×0.07λ×0.009λ. Moreover, the specific absorption rate is also analyzed on human head phantom. The analysis demonstrates an 35.93% reduction in the SAR value at 2100 MHz. Using negative refractive index metamaterials as a shield, the human body can be protected from electromagnetic radiations.

This paper is aimed to present a very small sized patch antenna for UWB applications. The antenna used microstrip feed-line. This antenna is very small in dimension. The total size of the antenna is 20×18mm ² . Triangular slots in the partial ground plane, are used to get a better bandwidth. The antenna has VSWR<;2 over the bandwidth. The whole designing and simulation process of the antenna is done by CST Microwave Studio software.

This letter reveals a $30 x 18$ mm$²$ metamaterial unit cell using coupled rectangular split-ring resonator (SRR), fabricated on only one side of the epoxy resin fiber substrate material. The proposed design consists of two separate SRRs outside and three split array rectangles with a small rectangle inside. It gives a wide magnetic repose throughout the C-band (4-8 GHz) microwave frequency spectrum. In the lower frequency band, the inclusion shows a negative epsilon, and in the upper frequency band, it shows double-negative characteristics (bandwidths of 0.72, 0.52, 0.2, and 0.71 GHz) with low losses in the C-band frequency range. The perceptible novelty of the proposed metastructure is achieved negative permeability throughout the whole C-band maintaining an effective medium ratio of 4.5.