Current Issue : April - June Volume : 2013 Issue Number : 2 Articles : 5 Articles
A novel internal antenna has been developed for indoor reception of UHF terrestrial digital TV broadcasting. The overall size of\r\nsome configurations of the new antenna is less than 2 cm3, and its weight is less than 1 gm. It is made of a flexible material that can\r\nbe bent or folded and shaped in any form. It is an unbalanced resonant antenna that does not need a matching circuit. The new\r\nantenna can be fully embedded inside TV sets or portable computers. It has a bandwidth of about 68%. Thus, it can also cover the\r\nbands of GSM and CDMA, which is advantageous in case of portable computers. The new antenna is linearly polarized. It can be\r\neasily modified to be dual polarized by combining two orthogonal antennas with one or two feed points. The overall efficiency of\r\nsome configurations of the new indoor digital TV receiving antenna is more than 80%, and its peak gain is about 2 dBi over the\r\nwhole UHF band. The peak gain can be increased to more than 5 dBi by adding EBG (electromagnetic bandgap) structures. The\r\nEBG structure also increases the efficiency to around 90%....
A downconverting second harmonic self-oscillating mixer (SOM) is developed for low-cost wireless communications applications.\r\nIncorporating resonant cell in the SOM, we can provide suitable oscillation for generating LO and terminations to all major\r\nunwanted mixing products, leading to high conversion gain design. The proposed SOM was measured with 8.5 dB downconversion\r\ngain at the RF frequency of 8.2 GHz RF, LO frequency of 4.0 GHz, and IF frequency of 0.2 GHz. The proposed design achieves\r\nhigher conversion gain than that of the SOM without resonant cell....
An approach to reconstruct buried objects is proposed. It is based on the integral equations of the electromagnetic inverse\r\nscattering problem, written in terms of the Green�s function for half-space geometries. The full nonlinearity of the problem is\r\nexploited in order to inspect strong scatterers. After discretization of the continuous model, the resulting equations are solved\r\nin a regularization sense by means of a two-step inexact Newton algorithm. The capabilities and limitations of the method are\r\nevaluated by means of some numerical simulations....
In this paper, and for the first time, the performance of various ultra wideband pulse modulation schemes are discussed and\r\ncompared in terms of narrowband interference robustness, symbol error rate, system complexity, data rate, and maximum transmit\r\npower with respect to transceiver distance and channel capacity. The channel model is the UWB IEEE 802.15.3a multipath indoor\r\nchannel model under additive white Gaussian noise. The transmit power was evaluated by integrating the fifth derivative of the\r\npower spectrum density of the Gaussian pulse over the whole bandwidth....
A highly selective planar band pass filter is proposed for satellite receivers to suppress intermodulation components. The 4-pole\r\nfilter has a center frequency of 19.825 GHz with a bandwidth of 240 MHz. The measured quality factor is over 600 and the insertion\r\nlosses are 4.1 dB. The micromachining technological process is used to fabricate this filter. A BCB (benzocyclobutene) thin layer\r\nis used as an electrical and mechanical support for the filter. The compatibility of the BCB with the spatial constraints was tested.\r\nVarious tests were accomplished for this purpose and the results of all these tests are presented in the paper. The tests showed a\r\nvery small influence of the temperature variation and high temperature storage test and practically no influence of the radiation\r\ntest on the circuit....
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