Abstract The objective of the present study is to evaluate the Specific Absorption Rate (SAR) within the human head model exposed to the radiation of planar monopole antenna with T-shaped coupling feed and an inductive shorting strip. The presented design has a compact structure, a planar configuration and occupying a small size of 36×20mm2. Two wide bands can be generated by the proposed antenna 546 MHz (734-1280 MHz) and 1066 MHz (1934-3000 MHz) for the LTE/WWAN/WLAN internal mobile phone. The antenna performance parameters comprising return loss, radiation patterns, and gain are discussed. In this research work four different human head models have been implemented: homogenous spherical head, spherical seven layer model, Specific Anthropomorphic Mannequin (SAM) phantom and HUGO human head model. On the other hand the effects of operating frequency and gap distance between the mobile phone antenna and the human head model on distributions of the SAR inside the human head are investigated. All the simulations are done for three different distances between the antenna and the head model (5 mm, 10 mm and 20 mm). Moreover, the SAR levels for the head tissues are calculated in accordance to the two currently accepted standards: Federal Communications Commission (FCC) and International Commission on Non-Ionizing Radiation Protection (ICNIRP).

In this paper, a new microstrip diplexer using open loop resonators with compact size and high isolation is designed and fabricated for the WLANs (IEEE 802.11b/g at 2.4 GHz and IEEE 802.11a at 5.2 GHz) applications. The diplexer is formed by two dual-mode band pass filters (BPFs) using an asymmetric fork-form feed line and two open loop resonators. The diplexer has less than 3 dB insertion loss and the isolation between the two channels is more than 25 dB. Furthermore, the proposed diplexer shows several transmission zeros beside the pass bands which improves the selectivity of the BPFs and thus improves the isolation between lower and upper channel filters and achieves a significant attenuation of the undesired harmonics. The electrical performances of the diplexer are investigated numerically by using Momentum integrated in ADS Agilent and CST microwave software. Good agreement between the simulation and measurement results is achieved.

A wideband diplexer in waveguide technology is designed to demonstrate the feasibility of using stepped waveguide junctions for diplexer designs. It consists of a channel filter, a low pass filter and a T E-plane junction. To validate the previous concepts, a C-band diplexer was constructed and tested using conventional milling techniques. The relative bandwidth of the whole diplexer is about 64%. The inputs and outputs return losses were less than 23dB, the isolation is better than 60dB and the transmission loss was 0,1dB. Moreover, a manufacturing tolerance has been taken into account at the design step, and therefore, the designed diplexer need not be tuned after manufacture.

En este trabajo se presenta el diseño teórico de un duplexor de gran ancho de banda usado en tecnología de guía de onda basado en uniones con varios pasos. El dispositivo está formado por un filtro pasa banda, un filtro pasa bajo y una unión T plano-E. Para validar el diseño propuesto, un duplexor en banda C fue construido y medido utilizando las técnicas clásicas de fresado. El ancho de banda relativo logrado es de aproximadamente de un 64%. Las pérdidas de retorno en los puertos de entrada y de salida están por debajo de los 23 dB, el aislamiento es mayor que 60 dB y las pérdidas de inserción son de 0,1 dB. Además se consideraron las tolerancias mecánicas de fabricación en la etapa del diseño, que probaron que el duplexor no necesita ajustes adicionales después de ser construido.