Search

In this article, a four-antenna module in a capsule endoscopy is proposed for multiple-input multiple-output (MIMO) operation to achieve the purpose of real-time transmission of high-resolution images with high data rates. For compactness, the proposed design adopts conformal architecture and fully utilizes the inner wall space of the capsule body to accommodate four antennas in the very limited space of the capsule endoscope. For the availability of MIMO operation, three different technical approaches are used to decouple or improve the isolation between neighboring antenna elements and between diagonal antenna elements. System considerations (interaction between the electronic components and the antenna in the endoscope) and specific absorption ratio (SAR) evaluation are performed to verify the robustness and human safety of the proposed design, respectively. In addition, link margin analysis and MIMO channel parameter studies are carried out to verify the wireless telemetry performance and MIMO operation performance, respectively. Antenna prototypes were fabricated and implanted in minced pork for ex-vivo measurements (S-parameters, gain, and radiation patterns). The measured overlapping impedance bandwidth of the four antenna elements is 120 MHz, which can fully cover the 915 MHz industrial scientific medical (ISM) band. The measured isolation between the neighboring antenna elements and the diagonal antenna elements is better than 20 and 10 dB, respectively. The measured maximum peak realized gain is −18.1 dBi. [ABSTRACT FROM AUTHOR]

In this article, an antenna with quasi-isotropic radiation pattern is proposed in a 915 MHz industrial, scientific, and medical (ISM) band for robust communication with external devices. The overall structure of the proposed antenna is a folded inverted-F antenna (FIFA). In the simulation, the proposed antenna is integrated with dummy electronics to form a fully encapsulated capsule endoscope architecture. These dummy electronics are encapsulated in a copper cylindrical bucket used as the antenna ground to avoid electromagnetic (EM) interference between these dummy electronics and the antenna. The spherical phantom model is used in the initial design of the proposed antenna. Subsequently, an anatomical realistic phantom was used to evaluate the performance of the proposed antenna in a more realistic human environment. The simulated gain variation (GV) of the proposed antenna in the regular spherical phantom is about 8 dB, and the reflection and other factors caused by the irregular shape of the realistic human tissue environment lead to the GV of the antenna in the anatomically realistic phantom that is about 4 dB. The measurement of reflection coefficient and radiation pattern is carried out in a semisolid muscle-mimicking phantom using a fabricated prototype of the proposed antenna. The measured GV value is about 10.5 dB. Finally, the specific absorption ratio (SAR) was calculated to meet the human safety regulations and the communication link budget was calculated to evaluate the wireless biological telemetry performance of the proposed antenna. [ABSTRACT FROM AUTHOR]