An exact analysis for magnetostatic surface wave excitation by a single microstrip is presented. Conventional approaches for such an excitation problem do not explain experimental results in a reasonable manner. The theory proposed here explains radiation resistances obtained by experiments, owing to having considered the edge conditions and an expansion form of excitation current on the microstrip properly.

An omnidirectional microstrip antenna using a parasitic cylinder is presented. A rectangular patch is formed on a dielectric substrate and it's completely covered with an aluminum cylinder which is somewhat shorter than a half of free space wavelength. Under such configuration the aluminum cylinder works as a parasitic element. This antenna can provides uniform omnidirectional radiation patterns and a broad frequency bandwidth. In this paper an experimental method for designing such an element is described. Measured input impedance characteristics, current distribution around the surface of the cylinder and patterns are also shown. By properly adjusting the coupling intensity between the patch and the parasitic cylinder a broad bandwidth antenna element can be realized. Some methods to adjust the coupling intensity are shown. A wide bandwidth element up to 14% for VSWR1.5 is obtained. Arranging many patches lengthways on a substrate and placing metallic cylinders around each patches, we can realize a high-gain and broad bandwidth collinear antenna.

This letter proposes a microstrip band elimination filter having an optically controlled small gap on a resonant section for the shift of the eliminated frequency range using the semiconductor plasma. The basic characteristics of this filter are analized theoretically utilizing the (FD)2TD method.

For the effective control of microwaves in the frequency domain, we propose a new method utilizing current distributions of standing waves on the terminated microstrip line. We analized a short ended microstrip line using the (FD)2TD method to indicate the effectiveness of our proposal. Further we proposed an optically controlled microstrip filter as an application of this method.

Numerical solutions for the near-field of microstrip antennas are presented. The field distribution is calculated by taking the inverse Fourier transform involving the current distribution with the help of the spectral-domain moment method. A new technique to save the computation time is devised, and the field pattern of the circularly polarized antenna is illustrated.

In this letter, the effectiveness of the quasi-TEM approximation is studied for the microstrip line including optically induced semiconductor plasma region. This approximation is considered to be efficient under several restrictions such as the upper limit of the microwave frequency and the plasma density.

We analyze the mutual coupling between two microstrip antennas (MSAs) with the finite-difference time-domain (FDTD) method. It is suitable for substrates which have a complex configuration or include feed line structures. The mutual coupling between two MSAs on discontinuous orthogonal substrates is successfully calculated.

In this paper, the characteristics of microstrip lines near the edge of dielectric substrate are analyzed by improving the rectangular boundary division method. The numerical results indicate the changes of the characteristics of a microstrip line when the strip conductor is closely located to the edge. When the distance the dielectric substrate edge to the strip conductor is less than the thickness of dielectric substrate, the effects of the edge on the line characteristics are no longer negligible. The numerical results in this paper show high computation accuracy without increasing computation time. Our improvement is effective for the analysis of the microstrip lines both for the narrow strip conductor and the strip conductor close to the edge. The relative errors between the numerical results and the measured values are less than 1.2%.

In this paper, boundary integral equations are derived from the Green's identity of the second kind in circular cylindrical coordinates, and are applied to determine the resonant frequencies of shielded circular ring and disk resonators. The integral equations are numerically solved by discretizating the integration path representing the air-dielectric interface and the surface of thick strip conductor. Because of the choice of the eigen-functions as weighted functions instead of Green's functions, the overall integral path length is shortened and computational time is reduced. Computational results on thick circular disk and ring resonators are compared with other available numerical results and experimental data.

For a method to control the microwave coupled lines with optically induced plasma effectively, we propose the selective mode-control method, which restricts controlled modes to a selected one. We analyzed the basic characteristics of coupled microstrip lines theoretically by using the spectral domain technique and indicated the effectiveness of this method with the aid of numerical results. Further, we designed an optically controlled change-over switch as an application of this method.