[Show abstract][Hide abstract] ABSTRACT: A new compact tapered microstrip monopole-like slot antenna for ultra-wideband (UWB) applications is proposed and studied both numerically and experimentally. The antenna is similar to the conventional microstrip monopole-like slot antenna; however, by introducing a tapered slot, UWB performance may be obtained. The dimensional parameters of the antenna and the corresponding current distribution on the conductor surface of the antenna are investigated numerically first. Based on numerical results, some prototypes are designed, fabricated and measured. The properties of the antenna, including return loss, radiation patterns and gain have been investigated experimentally again in order to confirm numerical results. Furthermore, the performance for the antenna when mounted in a handset is also investigated experimentally. As is reported, the operation bandwidth of the antenna is from 2.91 to 12 GHz, which is over 4:1. Relative omnidirectional and constant radiation patterns can be obtained over the entire bandwidth
Full-text · Article · May 2007 · IET Microwaves Antennas & Propagation
[Show abstract][Hide abstract] ABSTRACT: An equivalent expressions for the structures singular value is proposed, leading to an alternative algorithm for its computation. The approach is based to the geometric properties of the m-form numerical range of certain tuples of matrices. Similar to previously considered schemes, the algorithm proposed is proved to give the correct value for block structures of size up to three. For larger sizes, insight is gained into the question of the possible gap between the structured singular value and its known upper bound
No preview · Article · Feb 2007 · IEEE Microwave and Wireless Components Letters
[Show abstract][Hide abstract] ABSTRACT: A modified form of the time domain electric field integral equation (MFTD-EFIE) is proposed for determining the transient scattering from arbitrarily-shaped conducting bodies. In the analysis, the 2nd time derivative of the magnetic vector potential is approximated with a second-order central finite difference, and the time derivative of the electric scalar potential is averaged over time. The details of an implicit scheme for MFTD-EFIE are also outlined. Owing to the breaking of Courant condition, the method not only behaves efficiently but also yields stable transient responses. Numerical computations are carried out for quite a few conducting structures, such as plate, cube, hemisphere and cone, which demonstrate the accuracy and the efficacy of the proposed method.
No preview · Article · Jan 2007 · Journal of Electromagnetic Waves and Applications
[Show abstract][Hide abstract] ABSTRACT: A novel technique for simultaneously extracting electromagnetic responses in time and frequency domains is presented. The method involving simultaneous generation of early time and low frequency information employs a nonlinear optimization scheme to find the optimum natural frequency so as to achieve the best performance. Numerical examples are presented to demonstrate the validity of the proposed method
No preview · Article · Dec 2006 · IEEE Microwave and Wireless Components Letters
[Show abstract][Hide abstract] ABSTRACT: A novel frequency notched ultra-wideband (UWB) fractal printed slot antenna is proposed. The antenna is similar in configuration to a conventional microstrip-fed wide slot antenna, however, by introducing a Koch fractal slot, not only the size of the antenna is reduced significantly but also frequency notched function is achieved. Several properties of the antenna such as impedance bandwidth, frequency notched characteristics, radiation patterns and gain, have been investigated numerically and experimentally in detail. As will be seen, the operation bandwidth of the antenna is from 2.85 to 12GHz, in which a frequency notched band from 4.65 to 6.40GHz may be achieved, and relatively stable, omnidirectional radiation performance over the entire frequency range has also been obtained.
Full-text · Article · May 2006 · IEEE Microwave and Wireless Components Letters
[Show abstract][Hide abstract] ABSTRACT: A new frequency notched ultra-wideband microstrip slot antenna with a parasitic tuning stub is proposed. The antenna is similar in configuration to a conventional microstrip slot antenna; by introducing a parasitic open-circuit tuning stub, flexible frequency notched function is achieved. Several properties of the antenna, such as frequency notched function, antenna transfer function and gain, have been investigated. As is reported, the operation bandwidth of the antenna is 2.91-11.16 GHz, in which a frequency notched band of 5.10-5.85 GHz has been achieved. Furthermore, good ultra-wideband linear transmission performance over the entire operation frequency range has also been achieved.
Full-text · Article · Oct 2005 · Electronics Letters