This paper extensively investigates the Specific Absorption Rate (SAR) variations with respect to the category and size of the host device, frequency, and separation distance between a wireless terminal and a phantom. It is shown that SAR variations due to the host device depend on all of the conditions. SAR measurements were also conducted for comparison to the numerical results. The measurement results mostly support the numerically obtained results. Note that more attention should be given on the SAR measurement when the frequency is low such as 835MHz and the separation distance is not short, e.g., 15mm.
Binary codes for a multi-range-resolution radar are proposed. Inverse filters can be then used for a multi-range resolution radar and compress the proposed codes to different pulse widths. These binary codes are compressed to several sub-pulses, only if a matched filter is applied. We describe that the compressed pulses have very small pulse compression losses and side-lobe amplitudes, even though the binary codes are compressed to the pulse width smaller than the reciprocal of the bandwidth of the codes. This fact is confirmed by computer calculations.
Ultra wideband (UWB) technology in low band has being attracted considerable attention for high-speed and real-time transmission from inside to outside human body. However, it suffers from large attenuation and shadow fading in human tissues. A diversity technique is expected to provide effective improvement on its communication performance. This study aims to derive an approximate model for correlated in-body to on-body diversity channel and clarify the diversity effect. First, correlated statistical distribution between each two single signals is approximated as a lognormal sum distribution. Then two flexible parameters s1 and s2 in the lognormal sum approximation are optimized to obtain the probability density function (PDF) of the diversity channel. Finally the average bit error rates (BERs) are calculated theoretically to clarify the diversity effect, and its validity is verified by computer simulations.
Considering the very short distance between transmitter and receiver in the near-field MIMO system, the impact of the radiation pattern of each antenna element is not neglectable. In this paper, the dual-dipole arrays are utilized to investigate the effect of HPBW (half-power beamwidth) on channel capacity. The HPBW can be changed by varying the internal distance between two dipoles in one element. With a proper HPBW of the antenna element, the channel capacity of a dual-dipole array is improved obviously from a conventional dipole array. And the optimum HPBW is found to be approximately 50°.
A measurement method by comparing the time domain characteristics of impulsive electromagnetic noise and light emission was proposed to identify the noise from LED light bulbs which generated electromagnetic interference. To identify their noise, the waveform of the electromagnetic noise and light intensity from the LED lamp was measured simultaneously using an oscilloscope. This method identified the noise by means of property that the LED light bulb had a product-specific switching pattern corresponding to the power supply, both of radiation of impulsive electromagnetic noise and amplitude modulation of light emission from the LED light bulb occurs in synchronization with it. The validity of the proposed method was experimentally demonstrated.