No abstract

This paper presents a detailed and systematic investigation of the reproducibility of specific absorption rate (SAR) measurements using textile antennas and their simulation accuracy. The ability to accurately predict the SAR is very important for practical textile antenna designers since certified SAR measurements are costly. To that goal, the SAR values of a range of textile antennas operating in various bands of the IEEE 802.15.6 and 802.11 standards are evaluated. The selected textile antenna topologies for the evaluation differ in terms of the bandwidth behavior (broadband, dual band, and ultrawideband). They are chosen to be distinct, have been fabricated using an array of conductive textiles, and are benchmarked against similar structures made from a flexible conductor. SAR values are evaluated at three different frequencies, i.e., 2.45, 5.2, and 5.8 GHz, respectively, using a commercial electromagnetic solver and a certified experimental setup. Factors affecting the SAR behavior are presented and discussed. Results indicate that antennas without a rear ground plane are producing almost three times the SAR of textile antennas that feature a full ground plane. The results of this paper point out that the repeatability of the measurements is about 10Q and that the agreement between simulations and measurements is on the order of about 17Q.

No abstract

Abstract-Agricultural wastes are considered not useful and are commonly dumped or burned after crop harvesting. Rice husks from paddy (Oryza sativa) are example of agricultural wastes. Rice husks have been investigated as the material for the pyramidal microwave absorbers. The setup for the fabrication and measurement of the rice husks pyramidal microwave absorbers are discussed. An 8 × 8 array of pyramidal microwave absorber using the rice husks-polyester-MEKP mixture has been designed and fabricated. There are four main stages in this work: the collection of the raw rice husks materials, the mould fabrication, the pyramidal microwave absorber fabrication and the experiments performed to determine the reflection loss performance of the rice husks pyramidal microwave absorbers. Experimental results show close agreement with the simulation results (using CST Microwave Studio). Results so far have indicated that rice husks have great potential to be used as the materials for the pyramidal microwave absorbers.

Abstract-We investigated a dielectric resonator ceramic microstrip patch antenna. The antenna was formed using barium strontium titanate (BST), which had a dielectric constant of 15. A new approach, i.e., the use of a high temperature dielectric probe kit, was used to determine the dielectric constant of BST. A computer simulation technology (CST) microwave studio was used to simulate the BST array antennas, taking into consideration the dielectric constant. We also measured the gain of the antennas loaded with two-, four-, and six-element arrays of the BST antenna and found that the gain of a six-element BST array antenna was enhanced by a gain of about 1.6 dB over the four-element BST array antenna at 2.3 GHz. The impedance bandwidths of these BST array antennas for voltage standing wave ratio (VSWR) < 2 were in the application ranges,