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This paper presents novel designs, analyses, and simulations of two miniaturised pyramidal double-ridged horn (PDRH) microwave antennas for medical imaging systems. The PDRH antennas have been optimised to operate within a ceramic material filling with permittivity of 41 (which approximately is the permittivity of the human skin in the intended frequency range), in order to make the compact antennas,...
This paper presents a low-cost UWB radar system for imaging concealed metallic targets. A rotating linear UWB antenna array is adopted to form a 2D aperture. LabVIEW is used to enable an automated control of the array. Two imaging algorithms, i.e. Delay-and-Sum (DAS) and Time Reversal (TR) are employed in simulation and experiment. It is shown that the DAS method is better at imaging in free space,...
A novel compact antenna design for ultra wideband (UWB) applications is presented. The proposed miniature antenna is realised by combining three miniaturisation techniques. The optimal design of this type of antenna can offer an ultra-wide 10-dB impedance bandwidth with reasonable radiation properties. It also exhibits a very small dimension, 12mm×23mm in physical size and 0.24λ (at 3.1 GHz) in electrical...
The detection of concealed metallic weapons in bags/suitcase by using UWB (ultra widbeband) imaging is a cheap alternative to the security in the airport, subway or public area, compared to X-ray machines. In this paper, we have proposed and studied a novel UWB imaging system, including a rotating UWB antenna array, RF components and the 2D implementation of the delay-and-sum (DAS) imaging algorithm.
Achieving high data rate greater than 200Mbps for MB-OFDM UWB communications is a challenging task. Constrains of limited power and degrading transmission medium are the key hurdles. Currently most existing data systems can reach a data rate of only 80Mbps. This study proposes the use of spatial diversity to enhance the MB-OFDM UWB system performance while achieving high data rate. Spatial diversity...
Time domain performance of a compact Ultrawideband (UWB) antenna is studied in this paper. The antenna geometry and its frequency domain behaviour are briefly described. A comprehensive time domain investigation of the antenna is then carried out. It is demonstrated that the compact UWB antenna generally presents a good performance in both the frequency and the time domain.
In this paper, an adaptive modulation technique is proposed in a MultiBand Orthogonal Frequency Division Multiplex Ultra Wide Band (MB-OFDM UWB) communication system, to improve the BER performance in a frequency selective fading channel. The modulating bits are varied across the sub-channels depending on the signal to noise ratio (SNR). Sub-channels experiencing severe fading employ lower or no bit-loading...
In this paper, a printed compact UWB antenna is presented. A miniature size of the antenna has been achieved by integrating two miniaturisation techniques utilised in and, i.e. the quasi-self-complementary structure and the tapered slot. It has been shown that the optimal design of this type of antenna can offer an ultra wide 10 dB impedance bandwidth with reasonable radiation properties. Key parameters...
A printed miniature ultra wideband (UWB) antenna has been studied by exploiting a quasi-self-complementary structure and a tapered radiating slot in this paper. The optimal design of this type of antenna features an ultra wide impedance bandwidth with reasonable radiation patterns. It exhibits a rather compact physical dimension of 19mm??16mm, corresponding to an electrically size of 0.19??. A good...
A time domain study of a small quasi-self-complementary UWB antenna is presented in this paper. A brief description of antenna geometry and its frequency domain performance are illustrated first. A comprehensive time domain investigation of the antenna is then conducted. It has been demonstrated that the small quasi-self-complementary UWB antenna generally exhibits a good performance in both the frequency...
A brief review on our recent work on the miniaturised UWB antennas is presented. Three compact designs of UWB antennas are exemplified to illustrate their respective features and operations.
In this paper, the miniaturization of a printed circular disc monopole antenna is investigated. It is shown that by halving the original antenna and adjusting the coplanar ground plane width, an even wider impedance bandwidth at the lower end can be obtained. Furthermore, a clear physical explanation is provided to illustrate the mechanism of this type of half circular disc antenna.
This paper presents an investigation of cross ring/disc antenna for UWB applications. A coaxial cable fed cross the ring antenna with satisfactory -10 dB return loss bandwidth is firstly designed. In order to minimize the radiation pattern distortion at 9 GHz, an extended ground plane is then introduced. A comparison of performance of four different kinds of cross ring/disc antennas is also illustrated.
A 4-element tapered-slot-fed antenna array is proposed for directional UWB applications. The performance of the antenna array and important parameters are investigated both numerically and experimentally. Results show that the array gain and radiation patterns are heavily dependent on the separation between the two adjacent elements. A gain of 13 dBi is obtained when the element separation is properly...
An ultra-wide band (UWB) antenna sub-system has been developed for testing the Autonomous Interference Monitoring System (AIMS) capabilities in a set of field trials scheduled for UK Office of Communications (Ofcom), the independent regulator and competition authority for the UK communications industries. The prototype antenna is a compact planar structure and easy-to-install, thus reducing the planning...
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