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Basing on the characteristic mode theory, this paper develops the concepts of source-mode (SM) couplings and mode-mode (MM) couplings, which characterized by the modal weighting coefficients and the inter-modal coupling coefficients, respectively. It is found that SM couplings could be adjusted by MM couplings when feeding configuration remains unchanged. Therefore, just by properly adjusting mode-mode...
Recently, a public attention to ground subsidence due to the subsurface cavities in the urban area is growing. To prevent such catastrophe, a ground-penetrating radar (GPR) technique is being widely used to image and detect roadbed cavities. In this paper, properties in timedomain of antenna configurations are investigated to construct a bistatc GPR system. The system is categorized into two types:...
A fundamental study was focused on the investigation of wireless power transmission by near-field coupling from the view point of the antennas. Two types of antennas - dipole and loop antennas - were used as the transmitting antenna and the receiving antenna for electrical near-field coupling and for magnetic near-field coupling, respectively. The relationships among the power-transmission efficiency...
Wireless embedded sensors are ideally suitable for monitoring concrete structures because of their small size and ability to measure various quantities inside concrete. Wireless power transmission for such sensors embedded in plain/reinforced concrete slab is studied here. The return loss and transmission loss of dipole and patch antennas are studied at typical RFID frequencies. Also, the antennas'...
In this paper, we treated analytically the cellular phone antenna radiation parameters in the presence of a human body and the electromagnetic absorption concept by a human body in different realistic talking situations (in free space, in conductive environment, indoor, outdoor) is also investigated. Numerical investigations have been carried out to analyse the EM field coupling problem from cellular...
The integral-differential equation for the current of an electrically small antenna inside a resonator, which is induced by given sources, is solved by the so-called ldquomethod of small antennardquo. The calculated input impedance of the antenna in the resonator and the calculated coefficients of the mutual coupling between two antennas are compared to experimental measurements, performed within...
Recently, the near-field RFID systems operating at either LF (125-134 kHz) or HF (13.56 MHz) bands have been widely used due to the matured technology. However, the larger size of the antennas used in the LF/HF band systems limits their commercial applications. Thus, it is straight forward to reduce antenna size by designing the system in a higher frequency band, such as the UHF (860-960 MHz) band...
It is well known that spatially separated antennas can provide uncorrelated signals in a rich scattering environment. Under suitable conditions, orthogonally polarized antennas can provide uncorrelated signals without requiring any or much spatial separation. The channel capacity gains that result from MIMO (in general) depend heavily on the scattering environment. In this paper, we are interested...
In this paper, a novel and simple dual-band planar omni-directional antenna is proposed. Through proper adjustment of the couplings between the two coupling arms and the main dipole-based radiating section, the proposed antenna can operate either in the wideband mode or dual-band mode. Operated in the dual-band mode, the proposed antenna is able to cover both 3.25~3.85 GHz and 5.25~5.85 GHz for WiMAX...
A novel technique of suppressing coupling between two main antennas is presented. By inserting complementary radiation structure that is shorted (shorted radiation structure: srs), coupling between antennas in the commercial handset is dramatically decreased without the variation of return losses and efficiency.
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