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A novel exponentially tapered TEM horn antenna is presented. It is fed directly by a coax through a compact transition section and possesses a wide bandwidth, good radiation characteristic, and easy integration with microwave circuits. Two specially tapered metal flares have been designed to make a wideband characteristic and reduce the reflection. To overcome aperture reflections at low frequencies and unbalanced aperture field at higher frequencies, an arc surface is added at the end of the flare plates, and an absorbing material is loaded on the outer surface of the flare section. Measured results show that the presented antenna has a wide bandwidth from 0.83 to more than 12.8 GHz under a return loss

A novel compact planar tapered-slot antenna for ground penetrating radar (GPR) system is proposed. The antenna is fed by a coplanar waveguide (CPW) and evolved from one slotline of the compact CPW. Another slotline of the compact CPW forms a magnetic antenna as a supplement to the tapered-slot antenna. Some discontinuous points on the compact antenna structure will produce a relatively strong reflection, so the resistive loading is introduced. In order to validate the antenna performance, one prototype is fabricated and measured. The results demonstrate that the impedance bandwidth of the tapered slot antenna can span 0.64-6 GHz with the VSWR below 2, which agrees well with the simulated result. The radiation characteristics of the proposed antenna are measured, and its application for moving target tracking is also validated in a GPR system.

The motion of a relativistic electron is analyzed in the field configuration consisting of a circular wiggler magnetic field, an axial magnetic field, and the equilibrium self-electric and self-magnetic fields produced by the non-neutral electron ring. By generating Poincare surface-of-section maps, it is shown that when the equilibrium self-fields is strong enough, the electron motions become chaotic. Although the realistic circular wiggler magnetic field destroys the integrability of the electron motion as the equilibrium self-fields do, the role the latter plays to make the motions become chaotic is stronger than the former does. In addition, the axial magnetic field can restrain the occurrence of the chaoticity.

The laws of reflection and transmission of harmonic waves at a plane interface between a linear dielectric and a nonlinear dielectric are carefully analyzed. The exact expressions of the reflective and transmissive fields are derived. The further discussions are made to the fields at the conditions of vertical incidence and phase-matching.

Based on the nonlinear dispersive relation for fundamental frequency, reflection and transmission from a multilayer nonlinear slab is discussed when a plane wave is obliquely incident on it. The higher order iterative approximations of reflectivity and transmittivity are derived. Some calculations are made on a single-layer slab and a two-periodic multilayer slab, which is composed of two different nonlinear dielectric plates. It was concluded by some discussions about the influences of nonlinearity to EM wave propagation.

In this paper, we put forward a new version of Cantor fractal multilayers, which are nonlinear medium, and investigate its properties of reflection and transmission when a plane wave is obliquely incident upon it. A new exact self-similarity algorithm that make use of the self -similarity of these structure are developed. The results for different stages of fractal growth within the first-order nonlinear approximation are found. Compared with the traditional chain-matrix approach, the scheme provides the reflection and transmission coefficients for any stage (S) with much less calculation time on a personal computer.