In this paper, we present an analysis of microstrip line with a trapezoidal dielectric ridge in multilayered media. The method employed in this characterization is called partial-boundary element method (p-BEM) which provides an efficient technique to the analysis of the structures with multilayered media. To improve the convergence of the Green's function used in the analysis with the P-BEM, we employ a technique based on a combination of the Fourier series expansion and the method of images. Treatment on convergence for the boundary integrals is also described. After this treatment, it requires typically one tenth or one hundredth of Fourier terms to obtain the same accuracy compared with the original Green's function. Numerical results are presented for two microstrip lines that have a trapezoidal dielectric ridge placed on a one-layered substrate and a two-layered substrate. These numerical results demonstrate the effects on the characteristics of the microstrip line due to the existence of the dielectric ridge as well as the second layer between the ridge and the fundamental substrate.

This paper presents a configuration of circularly polarized annular-ring microstrip antenna (ARMSA) and its design method to obtain high gain and low axial ratio including the analysis of finite ground plane effect using G.T.D. for personal satellite communication use. The ARMSA excited at TM21 mode through co-planar branch-line hybrid coupler for circular polarization produces a conical pattern which has high gain in low elevation angle. The relation of gain and axial ratio versus the dielectric constant of substrate are shown and the existence of the dielectric constant which satisfies two requirements, that is, high gain and low axial ratio are clarified. For car-top application, experimental results in the L-band showed satisfactory characteristics for vehicle antenna.

Resonant properties of resistance shunted tunnel junctions have been investigated using the RLCSJ model. We found that an increase in dc current resulted from an increase in impedance of the shunted tunnel junctions. The static and dynamic properties of the shunted tunnel junctions were described in detail by numerical simulations and experiments. The simulated and measured results showed good agreement in I-V characteristics. A Josephson array oscillator has been proposed using the resonant properties for increasing oscillator output impedance. We designed and fabricated the oscillator with 20 shunted tunnel junctions. The output power of the oscillator delivered to the load resistor was estimated to be about 0.5µW at 312 GHz.

A cavity model well suited for computed-aided design is developed to synthesize the dimensions of patches for a given resonant frequency, an input resistance and a substrate. The antennas which have been investigated are rectangular patches fed with either a microstripline or a coaxial probe.

In this paper, we present for the first time two three-dimensional analytical electrostatic Green's functions for shielded and open arbitrarily multilayered medium structures. The analytical formulas for the Green's functions are simply expressed in the form of Fourier series and integrals, and are applicable to the arbitrary number of dielectric layers. In combination with the complex image charge method, we demonstrate an efficient application to analyze microstrip discontinuities in a three-layered dielectric structure. Numerical results for the capacitance associated with on open-end discontinuity show good agreement with those from a previous paper and the effectiveness of using the analytical Green's functions to analyze three-dimensional electrostatic problems.

In this paper, we presented an analysis of single and coupled microstrip lines covered with protective dielectric film which is usually used in the microwave integrated circuits. The method employed in the characterization is called partial-boundary element method (p-BEM). The p-BEM provides an efficient means to the analysis of the structures with multilayered media or covered with protective dielectric film. The numerical results show that by changing the thickness of the protective dielectric films such as SiO2, Si and Polyimide covered on these lines on a GaAs substrate, the coupled microstrip lines vary within 10% on the characteristic impedance and within 25% on the effective dielectric constant for the odd mode of coupled microstrip line, respectively, in comparison with the structures without the protective dielectric film. In contrast, the single microstrip lines vary within 4% on the characteristic impedance and within 8% on the effective dielectric constant, respectively. The protective dielectric film affects the odd mode of the coupled lines more strongly than the even mode and the characteristics of the single microstrip lines.

In this paper, a waveguide-fed slot-coupled microstrip antenna is proposed as enhanced feeding structure of microstrip antenna and an analysis is pesented. The presence of dielectric substrate between a strip and a slot is explicitly taken into account in this analysis. The evaluation of the antenna characteristics is carried out using the method of moments and the spectral domain approach in terms of the electric current distribution on the strip and the magnetic current distribution on the slot.

A novel thick ground plane is proposed as a support for a slot-coupled microstrip antenna and as a heat sink for an MMIC installed on the back plane of the active array antenna. A multi-layer structure of ground planes is also studied for the benefit of easy installation of MMICs. The influence of this thick metal ground plane with a mono- and multi-layer has been investigated in detail. Both measured and calculated results of VSWR and calculated results of the back lobe are shown in detail. The calculated results of VSWR agree well with the measurements. It is made clear that the thickness of the ground plane can be extended to twenty times that of the antenna substrate while maintaining the antenna's performance. An LNA composing an MMIC was developed, attached to the back of the antenna, and operated at 23 GHz. The measured results of this active element agree well with calculated ones and confirm the applicability of the novel design.

A new mm-wave IC, constructed by flip-chip bonded heterojunction transistors and microstrip lines formed on Si substrate, has been proposed and demonstrated by using MBB (micro bump boding) technology. Millimeter-wave characteristics of the MBB region has been estimated by electro-magnetic field analysis. Good agreements between calculated and measured characteristics of this new IC (named MFIC: millimeter-wave flip-chip IC) have been obtained up to 60 GHz band. Several MFIC amplifiers with their designed performances have been successfully fabricated.

Design techniques are presented for high performance microstrip bandpass filters using GaAs FETs for loss compensation. The filters are based on conventional planar filter topologies with the addition of GaAs FET negative resistance circuits to amplify the signal within the resonators via a reflection-mode of amplification. Three practical filters have been demonstrated using these negative resistance techniques: (1) A filter employing an active loop configuration, (2) a dual-mode microstrip ring resonator filter, and (3) an end-coupled half-wavelength resonator filter. The investigation of this negative resistance method of loss compensation has led to the development of an exciting new type of miniaturised filter which employs MIC microstrip resonators with MMIC negative resistance chips bonded into the filter for loss compensation. This approach has the advantage of combining the proven capabilities of established MIC microstrip filter topologies with the excellent reproducibility of the MMIC loss compensation circuits.

In this paper, mutual coupling S21 between RMSA (ring-shaped microstrip antenna) elements was estimated by the EMF method based on the cavity model. Then, the validity of the proposed method was tested by experiments. The experiments confirmed satisfactory agreement between the computed and experimental data for S21 in both E- and H-plane arrangements. In addition, a circularly polarized planar array composed of R-MSA elements was designed on the basis of the data of S21. The experimental results of such a planar array demonstrated high performance in radiation pattern as well as axial ratio property. Furthermore, the active reflection coefficient Γ in the R-MSA array was also investigated in both equilateral and square arrangements. The computed results of active reflection coefficient in the array demonstrated high performance in both arrangements.

Recent works have shown that the size reduction of printed dipole antennas was possible thanks to a proper shaping of the radiating element. Following the same idea (choice of suitable shape), a shortened slot fed patch antenna exhibiting two step discontinuities, is described, analysed and optimized with a simple transmission line model. The shortening ratio (ρ) can reach 80% for matched antenna, printed on a substrate with a low dielectric constant (εr=2.2). The calculated results of input impedance are validated by experiment.

A light, thin and flexible applicator using a microstrip patch array for microwave heating is presented and tested in this work. The applicator is made of a flat silicone rubber bag, inside of which flows cooling water. EM coupling feeding is applied, which has no direct contact between the feed and the patch, to improve durability and reliability when it is repeatedly applied to the uneven surface of the heated portion of the human body. Simulations of SAR distribution are performed using the finite difference time domain (FD-TD) method. Simulated data are compared with the experimental ones using cubic and cylindrical phantom models with single and multielement patch applicators. Simulations of temperature distribution are also performed using the heat transfer equation. Simulated data are compared with the experimental ones using cubic and cylindrical phantom models. The simulated results agree well with the experimental ones. The results obtained here show that the multielement flexible microstrip patch applicator which operates at 430MHz can heat a relatively shallow and widespread area on the human body for hyperthermia treatments.

A new approach using radiation mode expansions is presented for calculating radiated fields from arbitrary distribution of electromagnetic sources in the half space region partitioned by a dielectric layer with a ground conductor. This method is applied to the calculation of radiation from microstrip-type antennas with a dielectric substrate of theoretically infinite extent. To be able to use this method, it is necessary to obtain first the field distribution around antenna patches, which is accomplished rather easily by using the FD-TD method. Radiation pattern calculations are presented for a rectangular patch antenna to verify the feasibility of this approach.

An efficient full–wave spectral domain moment method is developed to compute the current distribution and the radiation associated with microstrip discontinuities. Two techniques are used to increase the efficiency of the method of moments algorithm so that a transmission line of moderate electrical size can be analyzed in reasonable time.

A method using the microstrip line resonator is applied to measurements of the dielectric properties of a substrate and the surface resistance of a conducting strip line versus the frequency as well as the temperature. The variational expressions for the capacitance per unit length of several microstrip lines such as an inverted microstrip line and multi-layer microstrip lines are derived. The expression involves an integral along a semi-infinite interval, but the numerical integration is very easy. Effects of a buffer layer deposited on the substrate are investigated by using a multi-layer microstrip line model. The permittivity and the loss tangent of several dielectric materials are measured by the MSL and the IMSL or the multi-layer microstrip resonator. The measured surface resistance of copper and iron is also presented to show the validity of the present method. The surface resistance of a BSCCO thick film is also presented.

In this paper, we analyze high-Tc superconducting (HTS) microstrip antenna (MSA) using modified spectral domain moment method. Although it is assumed that the patch and the ground plane of the MSA are perfect electric conductors (PECs) in the conventional spectral domain method, we modify this method to compute the conduction loss of the HTS-MSA. In our analysis, the effect of the HTS film is introduced by the surface impedance which we can estimate by using the three fluid model and experimental results. This paper presents numerical results about the HTS-MSA, for example, the relations between the thickness of the substrate and the radiation efficiency, the temperature and the resonant frequency, and so forth. And we discuss the effective power range where the performance of the HTS-MSA is superior to that of the Cu-MSA.

This paper theoretically and experimentally investigates the mutual coupling between two ports of dual slot-coupled circular microstrip antennas. Presented are the effects of feed configuration, slot length, slot offset from the circular disk center, circular disk radius and the dielectric constant of the feed substrate on the mutual coupling. Based on these results, the antenna with low mutual coupling was designed. The mutual coupling of under -35dB at the resonant frequency was obtained.

The radiation patterns of a circularly polarized GPS microstrip disk antenna mounted on the roof of a car are analyzed using UTD. Based upon the excellent agreements between the calculated and the measured results in all the observation directions, the effects of the antenna location upon radiation patterns are discussed in detail. As the distance between the antenna and the edge decreases, the gain in the low elevation angle on the same side as the edge considerably decreases. The effects of the earth are also extracted. They cause the fine ripples in the low elevation angle, though they are negligible in macroscopical view. Furthermore, the validity of the simple design neglecting the earth and the plates other than roof is investigated. The errors are localized at low elevation angle. The results obtained in this paper are useful in the design of the general antennas for mobile communication.

A semicylindrical microstrip applicator system is proposed and designed, both for microwave heating and for noninvasive temperature estimation, in application to hyperthermia treatment. The experimental results showed that the system functions both as a heating device and as a means of noninvasive temperature estimation. Therefore, electrical switching of these two functions makes the system realize both heating and temperature estimation. These functions reduce the pain of hyperthermia therapy for patients. The system is constructed of a water-loaded cylindrical applicator. Thus, the whole system can be made compact compared to conventional applicators. This improvement allows for various merits, such as realizing a surface cooling effect and decreased leakage of electromagnetic (EM) waves. When the applicator is set as an array arrangement, the system can be used as a microwave heating device. The penetration depth can be varied by adjusting phases of the EM wave radiated from each applicator. The experimental results at 430 MHz showed that semicylindrical microstrip applicators can be expected to be valid for tumor heating at depths within 55 mm. Moreover, by measuring transmission power between the two applicators, the system can be used to estimate temperature inside the medium. The transmission power which was measured in the frequency domain was converted in the time domain. By such a method, temperature distribution was calculated by solving simple simultaneous primary equations. The results of the temperature estimation show that the number of estimated temperature segments which have an error within 0.5 is 28 out of 36. The system can be easily used as a temperature measuring applicator as well as a heating applicator.