Siddik Cumhur Basaran

Bu çalışmada, WLAN ve WiMAX uygulamaları için elektriksel olarak frekansı ayarlanabilir yeni bir düzlemsel evrilmiş-F anten (DEFA) tasarımı önerilmektedir. 30 × 25 × 10 mm3 boyutlarındaki antenin ana radyatörü simetrik olmayan kıvrımlı şerit elemanlarından oluşmakta ve frekans cevabı bu elemanlar arasında optimum konumda kullanılan bir PIN diyotu aracılığıyla dinamik olarak ayarlanabilmektedir. Sayısal tasarımı Ansoft-HFSS ve CST Microwave Studio benzetim yazılımları aracılığıyla gerçekleştirilen antenin prototip üretimi de gerçeklenerek, diyotun açık/kapalı durumları için geri dönüş kaybı ölçümleri alınmıştır. Önerilen anten diyotun kesim durumunda WiMAX bandında tek bent rezonans gösterirken, iletim durumunda 2.4 ve 5.2 GHz WLAN bantlarında rezonansa gelmektedir. Ayrıca E ve H-düzlemleri için ilgili frekans bantlarında oldukça düzgün ışıma karakteristikleri sergileyen antenin mutlak kazanç değerleri 2-4 dBi arasındadır.

This paper presents a compact implantable antenna’s design, fabrication, and measurement for biotelemetry applications. The proposed design with the size of 255 mm³ provides a triple-band operation that covers all the Medical Implant Communication Service (MICS: 402 MHz), Medical Device Radiocommunications Service (MedRadio: 405 MHz), and Industrial, Scientific, and Medical (ISM: 433, 915 and 2450 MHz) bands simultaneously. The compact structure with triple- band performance is essentially achieved by using a spiral-like radiator loaded with meandered and internal gear-shaped elements excited by a vertical coaxial probe feed. Also, the slots-loaded partial ground plane is utilized to improve impedance matching at the desired frequency bands. The design and analysis of the antenna were carried out using the Ansoft HFSS software in a homogenous skin model and the CST Microwave Studio in a realistic human model. The proposed antenna was fabricated to validate the simulated results, and characteristics of its return loss and radiation patterns were measured in minced pork meat. Moreover, realized gains and specific absorption rate (SAR) values of the antenna were numerically computed using the simulators. Based on the simulated and measured results, the proposed antenna performance was found to be comparable to the limited number of multiband implantable antenna designs reported in the recent literature.

A dual‐band implantable complementary split‐ring (CSR) antenna is proposed for Medical Implant Communication Services (MICS) and Industrial Scientific and Medical (ISM) bands biotelemetry applications. The proposed antenna is printed on a grounded RO3010 substrate and the total size of the compact design is only 14 × 14 × 1.27 mm³. The metallic top layer of the antenna is composed of three homocentric rectangular CSR elements and slots inserted between the rings. While the slots are used for fine frequency tuning, a shorting pin appropriately placed between the top copper radiator and the ground plane is utilized for miniaturization purpose. In order to improve impedance matching and enhance bandwidths of the antenna, we employ a hook‐shaped slot in the ground plane. The proposed implantable CSR antenna (ICSRA) is fed by a coaxial probe. The proposed ICSRA was fabricated and measured in two different gels mimicking the real human skin tissue at the MICS and ISM bands. Also, a prototype of ICSRA was measured in a real skin sample obtained from a donor rat for in vivo verification. The ICSRA provides 23.5% bandwidth at 460 MHz and 12% bandwidth at 2.34 GHz and it exhibits acceptable radiation pattern characteristics at the respective bands. The specific absorption rate values of the antenna satisfy the limits set by standard safety guidelines.

A frequency‐reconfigurable microstrip monopole antenna for WLAN applications is presented. Based on two side‐by‐side split‐ring (SR) resonators as the primary radiator, the antenna exhibits single or dual frequency operation that is tunable using an integrated switch. The antenna is electrically small, thanks to the SR structure, and exhibits similar radiation patterns for both frequency bands. The return loss and radiation pattern measurements of the fabricated antenna are in very good agreement with simulation results. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:55–58, 2015

A compact dual-band planar inverted-F antenna (PIFA) working in the GPS (1572 MHz), DCS (1800 MHz) and WiMAX (3500 MHz) frequency bands is presented. The antenna based on split-ring (SR) resonators provides 30% and 11% impedance bandwidth performance at the respective bands. Also, the antenna exhibits uniform radiation pattern at both frequency bands.