A compact wearable antenna with a novel miniaturized electromagnetic bandgap (EBG) structure at 2.4 GHz for medical application is presented in this letter. The design demonstrates a robust, compact, and low-profile solution to meet the requirements of wearable applications. The EBG structure reduces the back radiation and the impact of frequency detuning due to the high losses of human body. In addition, the structure improves the front-to-back ratio (FBR) by 15.5 dB. The proposed compact antenna with dimensions of 46 × 46 × 2.4 mm ³ yields an impedance bandwidth of 27% (2.17-2.83 GHz), with a gain enhancement of 7.8 dBi and more than 95% reduction in the specific absorption rate. Therefore, the antenna is a promising candidate for integration into wearable devices applied in various domains, specifically biomedical technology.

A frequency-reconfigurable microstrip patch switchable to slot antenna is proposed. The antenna is capable of frequency switching at nine different frequency bands between 1.98 and 3.59 GHz. The patch is resonating at 3.59 GHz, while the slot produces eight different operating frequencies between 1.98 and 3.41 GHz. Five RF p-i-n diode switches are positioned in the slot to achieve frequency reconfigurability. Simulated and measured results are used to demonstrate the performance of the antenna. The simulated and measured return losses, together with the radiation patterns, are presented.

A novel frequency and pattern reconfigurable slot antenna is proposed. Slot antenna produces a bidirectional radiation pattern, thus a reflector is positioned behind of the antenna to generate a directional radiation pattern. Two switches are placed in the slot to produce three reconfigurable frequency bands: at 1.82 GHz, 1.93 GHz and 2.10 GHz. The introduction of four slits at the edge of the ground plane offers pattern reconfigurability. To tune the beam angles, three switches are inserted into each slit. By manipulating the phase of upper and lower slits in the ground plane, the proposed antenna is capable of reconfiguring its beam to three different angles at 0°, -15° and +15°. The simulated and measured results of reflection coefficient and radiation patterns are presented and compared.

A frequency-reconfigurable microstrip slot antenna is proposed. The antenna is capable of frequency switching at six different frequency bands between 2.2 and 4.75 GHz. Five RF p-i-n diode switches are positioned in the slot to achieve frequency reconfigurability. The feed line and the slot are bended to reduce 33% of the original size of the antenna. The biasing circuit is integrated into the ground plane to minimize the parasitic effects toward the performance of the antenna. Simulated and measured results are used to demonstrate the performance of the antenna. The simulated and measured return losses, together with the radiation patterns, are presented and compared.

The recent advancement in the wireless technology has led to the advent of wearable antennas. These antennas are utilized for Wireless Body Area Networks (WBANs) purposes such as health-care, military sportive activities and identification systems. Compared to conventional antennas, wearable antennas operate in an environment which is in highly near proximity to the curved human body. Therefore, the wearable/flexible antenna performance parameters, including reflection coefficient, bandwidth, directivity, gain, radiation characteristic, Specific Absorption Rate (SAR), and efficiency are anticipated to be influenced by the coupling and absorption by the human body tissues. In addition, an electromagnetic band-gap structure is introduced in the wearable/flexible antenna designs to enable and give a high degree of isolation from the human body which also decreases the SAR dramatically. This paper reviews the state-of-the-art wearable/flexible antennas integrated with the electromagnetic band-gap structure on flexible materials concentrating on single and dual-band designs. Besides, it also highlights the challenges and considerations for an appropriate wearable/flexible antenna.

The design and analysis of a compact dual-band wearable antenna for WBAN applications is presented. The antenna was prototyped on a semi-flexible Rogers Duroid RO3003™ with compact dimensions of 41 × 44 mm ² which corresponds to 0.33 λ ₀ × 0.35 λ ₀ , where λ ₀ is the free space wavelength at 2.4 GHz. The antenna is designed in the preliminary stage to resonate at 5.8 GHz. An inverted U-shaped slot is added to the patch to create one more resonant frequency at 2.4 GHz. In order to enhance the antenna’s bandwidth and gain, two slots at the patch’s bottom edge and a partial ground are added. The measured percentage of impedance bandwidth at 2.4 GHz and 5.8 GHz are 3.75% and 5.17%, respectively. The gain is measured to be 3.74 dBi and 5.13 dBi and the efficiency is 91.4% and 92.3%, respectively at the operating bands. The measured radiation patterns exhibit a bidirectional and directional radiation pattern in the E -plane at 2.4 GHz and 5.8 GHz bands, while omnidirectional radiation patterns are observed in the H -plane. At 2.4 GHz, the SAR limits are simulated to be 0.955 W/kg and 0.571 W/kg for 1 g and 10 g of human tissue, while at 5.8 GHz, the SAR limits are 0.478 W/kg and 0.127 W/kg, respectively. Therefore, the proposed antenna has met the FCC and ICNIRP standards. Bending conditions and on-body measurements of the proposed antenna indicate that the antenna’s performance is unaffected. As a result, it is shown that the antenna possessed the ability to be utilized in WBAN applications.