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A scanning-beam Doppler radar has been presented which can detect moving intruders from a moving platform. The limitations of the scanning-beam sensor in terms of platform velocity and rotation rate were discussed for a fixed antenna beamwidth. Targets moving at any velocity relative to the platform can be detected, even when the person is moving along with the platform, producing no Doppler return...
A SIW- series fed DRA linear array was designed at millimeter wave range using two configurations. Then, a simple circuit model for the proposed antenna array was presented as a fast and easy way to predict the overall antenna return loss saving the huge CAD computation time especially for large arrays.
In this paper, a novel UWB TEM horn antenna enclosed in a dielectric medium has been proposed for microwave imaging in breast cancer detection. It obviates the use of coupling medium. Also, the outer surface of the dielectric enclosure has been covered by copper sheets and a microwave absorbing sheet to decouple the antenna from surrounding interferences. The design is accomplished through full-wave...
In this paper, a new H-guide antenna has been presented. The obtained results show that the proposed antenna can achieve approximately 12.0 dBi of gain at 9 GHz and has acceptable return loss from 8 to 10 GHz. Furthermore, the radiation patterns and insertion loss of the antenna have been presented and discussed.
A design for a reconfigurable planar quasi-Yagi antenna with a folded dipole driver element is presented. Reconfigurability of the operating frequency of the antenna is achieved by changing the effective electrical length of the folded dipole, which is controlled by a varactor diode. The predicted operating frequency of the quasi-Yagi antenna can be continuously tuned from 5.6 to 7.6 GHz using a typical...
An internal PIFA/slot antenna for quad-band mobile handset applications is presented. The quad-band operation for the bar-type mobile handset is obtained by the resonant modes of the slot antenna in conjunction with those of the PIFA. The proposed antenna has a compact size of 42 times 10 times 4 mm3. The quad-band operation includes GSM850 (824-894 MHz), GSM900 (880-960 MHz), DCS1800 (1710-1880 MHz),...
A novel tunable antenna is proposed to provide ultra-wide tunable range with a high selectivity. A reconfigurable matching network is implemented to achieve impedance matching at desired frequency of semi-ultra wideband (S-UWB) antennas, which can be designed in a straight forward manner. The L-C series matching network is chosen to demonstrate the performance by simulations. The simulation results...
This paper presents a detailed comparison of the results of a 3D FDTD numerical model and experimental measurements of the antenna response of a microwave tomography system. The FDTD algorithm uses the thin-wire approximation to model the antenna structure and a resistive voltage source is used to excite the signal. The algorithm was validated against experimental data obtained for an array of monopole...
Loop-tree bases are used to model the object in the current EPA scheme. Compared to the RWG based EPA, the new method can deal with the low frequency problem more accurately. Numerical results show the validity of the proposed scheme. More realistic and complicated testing examples will be considered in the future work.
The performances of a wideband passive repeater including two broadband antennas and a coaxial line are analyzed both from full-wave electromagnetic simulations and measurement data over 1.6 GHz bandwidth centered at 4 GHz. For carrier signal level lower than the detection threshold, the use of passive repeater can significantly improve the reliability of the wireless link.
Microstrip patch antennas with inset feed have been studied extensively over the past two decades because of its practical advantage when used in mobile wireless systems. The length of MPA, however, is comparable to a half wavelength with single resonant frequency and bandwidth around 2%. In this paper, we describe a novel approach to reduce the antenna size and provide multiband operation. Electromagnetic...
A compact low-cost planar antenna is proposed to cover the WLAN frequency bands centered at 2.4, 5.2 and 5.8 GHz. It was observed that the resonant frequencies of the antenna can be easily adjusted. The return loss in the 5.2 to 5.8 GHz range is effectively controlled by using a strip to short out the surface current. The antenna shows a donut-shaped radiation pattern in the E-plane and an omnidirectional...
This paper presents the design of a low profile, wideband, vertically polarized antenna to be used on an unmanned aerial vehicle (UAV) or airplane in place of multiple monopole antennas. The new antenna was modeled in Microwave Studio (MWS) and optimized with a genetic algorithm (GA). The GA minimized S11middot from 800 MHz to 2.4 GHz. Experimental measurements for S11middot and the antenna pattern...
A new procedure for an efficient solution of the problem of scattering from large cylindrically- shaped reflectors has been proposed in this paper. It utilizes the CBFs that are obtained by applying the SVD (singular value decomposition) procedure to analytically-derived basis functions. These bases, which are constructed by totally bypassing any conventional MoM-type computation, can be used for...
The electric field integral equations (EFIE) solved by method of moments (MOM) is widely used in scattering, antenna, and microwave circuit problems. However, it is well known that EFIE will break down when applied to electrically small structures or low frequency problems. A loop-star decomposition for the RWG discretization overcomes this problem and provides a valid solution from zero to microwave...
In this paper, we presented a new metamaterial antenna which consists of single and double layer of CRLH structure using thick substrate in the lower layer. The second layer is used to improve the matching of the antenna with the feeding structure. The results show the antenna efficiency has been improved by using the second layer.
In this work, we have used the opened waveguide cavity to enhance the isolation. The proposed reflector with the donor and receptor antenna satisfied the isolation, more than 80 dB as well as the gain and return loss of the antennas. Also the size of the reflector is reduced considerably compared with conventional reflectors.
In this paper, a dual frequency antenna with meandering slots is proposed. The effects of every slot of the proposed antenna are analyzed in detail using FEM. The proposed antenna has with an air-layer substrate of 13 mm and covers the required bandwidths of the GSM and WCDMA systems. The proposed antenna is especially suited for application in wireless communication repeater systems.
A novel PNM textile with extremely small thickness on the order of a few micron was characterized at millimeter wave frequencies (26.5 - 40 GHz), and the impedance analysis of the material was presented. The results show that the PNM is an excellent absorber for wideband applications; the highly polarized materials can be utilized for polarization detection and sensing applications. The impedance...
In the presented work, a reduced size planar UWB antenna, which avoids some of the above-mentioned shortcomings, is proposed. It has a very compact size with dimensions of (0.9 cm x 1 cm). The simulated performance of the proposed antenna in an environment, which is similar to the real situation in the breast imaging system, shows an ultra wideband behavior with high fidelity.
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