A new millimeter-wave (MMW), electromagnetic band-gap (EBG) structure is presented. The proposed EBG structure without the use of metallic vias or vertical components is formed by etching two slots and adding two connecting bridges to a conventional uniplanar EBG unit-cell. The transmission characteristics of the proposed EBG structure are measured. Results show that the proposed EBG structure has a wide bandgap around the 60 GHz band. The size of the proposed EBG unit-cell is 78% less than a conventional uniplanar EBG, and 72% less than a uniplanar-compact EBG (UC-EBG) operating at the same frequency band. Moreover, and despite the fabrication limitations at the 60 GHz band, the proposed EBG unit-cell provides at least 12% more size reduction than any other planar EBG structures at microwave frequencies. Its enhanced performance and applicability to reduce mutual coupling in antenna arrays are then investigated. Results show a drastic decrease in the mutual coupling level. This EBG structure can find its applications in MMW wireless communication systems.

This article proposes an efficient and complete wireless power transfer (WPT) system (WPTS) for multipurpose biomedical implants. The WPTS is composed of a self-diplexing implantable antenna, efficient rectifier, and WPT transmitter (WPT Tx). The proposed system is capable of simultaneously transmitting recorded data and recharging the batteries of the devices (so as to elongate the implant life). The WPT Tx occupies dimensions of 50 ×50 ×1.6 mm ³ and is optimized to effectively transfer power at 1470 MHz to a 55-mm deep implantable device. An efficient and compact ( 3.4 ×6.7 mm ² ) rectifier is used at 1470 MHz to convert the harvested RF power into a useful direct current (dc) power. The proposed rectifier circuit exhibits a high conversion efficiency of 50% even at an input power of -14 dBm and maximum efficiency of 76.1% at 2 dBm. The proposed self-diplexing implantable antenna occupies small dimensions (9.4 mm ³ ) and operates at 915 and 1470 MHz by exciting ports 1 and 2, respectively. The biotelemetry operation is performed using a 915 MHz band (port 1), and the rectifier circuit is connected to port 2 (1470 MHz) to perform wireless powering. The simulated results are validated by examining the individual elements (WPT Tx, rectifier, and self-diplexing antenna) and overall WPTS in a saline solution and minced pork. The results prove that the proposed scheme is suitable for biotelemetry and wireless powering of biomedical implants.

This article presents a low-profile multiple-input–multiple-output (MIMO) implantable antenna system, including a capsule endoscopy and a scalp implantation at medical implant communication service (MICS) band (402–405 MHz), and industrial, scientific, and medical (ISM) band (433.1–438.8 MHz). It consists of two elements with an edge-to-edge gap of $0.0018\lambda _{g}$ and overall dimensions of $\pi \times (5.65)^{2} \times 0.13$ mm ³ and is placed on a 0.13 mm-thick RO3010 ( $\epsilon _{r} = 10.2$ and tan $\delta = 0.0022$ ) substrate. The antenna is integrated with batteries, sensors, and electronic components in two different types of implantable devices (capsule and flat-type devices). The simulation result shows that the antenna has a fractional bandwidth (FBW) of 33.9%, a maximum realized gain of −30 dBi, and isolation of more than 26 dB. The fabricated prototype is measured in a saline solution and minced pork meat. The measured results are found in good accordance with simulations. The antenna parameters are calculated and showed a significant independence between the radiators. A link budget is estimated to be 78 Mb/s for a distance of 20 m. Thus, the proposed antenna is considered as a promising solution for high-data-rate medical applications such as capsule endoscopy, live surgeries, and other biomedical applications where the high data rate is required.

A quad-element multiple-input–multiple-output (MIMO) antenna is designed at 433 MHz industrial, scientific, and medical (ISM) band, to increase the transmission data-rate and minimize the multipath fading. The proposed MIMO antenna consists of semicircular meandered radiators with a shared ground. It is designed and optimized inside an implantable medical device in a human head model. The antenna’s results show a 10 dB fractional bandwidth of 38.26% (355–523 MHz) with a peak realized gain of −28.3 dBi. A high isolation ( $>$ 32.6 dB) between MIMO elements is obtained using a central metallic via. Specific absorption rate and link budget are analyzed to validate the effectiveness of this antenna. The 4 × 4 MIMO channel parameters are calculated and validated. Furthermore, this antenna provides a channel capacity of 19.9 bps/Hz which is about three times higher than the single-input–single-output configuration of $\approx$ 5.89 bps/Hz. Hence, this MIMO configuration is a promising candidate for high-data-rate head implants.

Design, fabrication and testing of millimeter-wave (MMW) dielectric resonator antenna (DRA) surrounded by electromagnetic band-gap (EBG) structure are presented. For this purpose, MMW mushroom-like, circular patch EBG (CP-EBG) cell is designed and fabricated. The propagation characteristics of the proposed CP-EBG structure are measured using the asymmetric microstrip line method. A cylindrical DRA incorporating the developed CP-EBG structure is then designed and its performance is evaluated with and without the CP-EBG around the 60 GHz bandwidth. Measurements show a significant improvement in the antenna radiation characteristics when it is surrounded by CP-EBG structure. A gain increase of up to 3.2 dBi is obtained while preserving the gain flatness over the suggested bandwidth ( ± 0.7 dB). An additional backlobe suppression of up to 6.5 dBi is achieved. Moreover, radiation toward substrate edges is significantly reduced.

Uncertainty quantification is an important aspect of engineering design, also pertaining to the development and performance evaluation of antenna systems. Manufacturing tolerances as well as other types of uncertainties, related to material parameters (e.g., substrate permittivity) or operating conditions (e.g., bending) may affect the antenna characteristics. In the case of narrow- or multi-band antennas, this usually leads to frequency shifts of the operating bands. Quantifying these effects is imperative to adequately assess the design quality, either in terms of the statistical moments of the performance parameters or the yield. Reducing the antenna sensitivity to parameter deviations is even more essential when increasing the probability of the system satisfying the prescribed requirements is of concern. The prerequisite of such procedures is statistical analysis, normally carried out at the level of full-wave electromagnetic (EM) analysis. While necessary to ensure reliability, it entails considerable computational expenses, often prohibitive. Following the recently fostered concept of constrained modeling, this paper proposes a simple technique for rapid surrogate-assisted yield optimization of narrow- and multi-band antennas. The keystone of the approach is an appropriate definition of the optimization domain. This is realized by considering a few pre-optimized designs that represent the directions of the major changes of the antenna resonant frequencies and operating bands. Due to a small volume of such a domain, an accurate replacement model can be established therein using a small number of training samples, and employed to improve the antenna yield. Verification results obtained for a ring-slot antenna, a dual-band and a triple-band uniplanar dipoles indicate that the optimization process can be accomplished at low cost of a few dozen of EM simulations: 62, 74 and 132 EM simulations, respectively. Result reliability is validated through comparisons with EM-based Monte Carlo simulations.