Microstrip antennas on various Uniplane Compact Photonic BandGap (UC-PBG) substrates are investigated. Particularly, anisotropic characteristics of UC-PBG is studied and applied to the design of microstrip diplexer antennas. Moreover, an Embedded UC-PBG (EUC-PBG) scheme is presented to overcome the strong backward radiation caused by the conventional UC-PBG antennas. Such antennas demonstrate the improved radiation properties over the conventional UC-PBG antennas, and the evidence on surface wave suppression is also demonstrated. Experimental results show very good agreement with theoretical predictions.

In this paper, a novel circuit structure of Push-Push oscillator using λg/2 microstrip resonator is proposed, in which a common resonator plays two functions of frequency determining and power combining. This type of Push-Push oscillator is named "Dipole Resonator Push-Push oscillator" here, where an additional power combiner circuit required in conventional Push-Push oscillators can be eliminated. The Push-Push oscillator adopting this design concept has the advantages of the easy circuit design, the simple circuit structure and the miniaturization of the circuit size. As a most simple example of this design concept, a K-band Push-Push oscillator using a λg/2 microstrip resonator is designed and achieved. The high output power of +8.4 dBm at the frequency of 21.68 GHz (2f0) is obtained with the phase noise of -100.5 dBc/Hz at the offset frequency of 1 MHz. Besides, a high suppression of the undesired fundamental frequency signal (f0) of -26 dBc is realized.

On a transmission line lowpass filter fabricated on a printed circuit board using open-circuited microstrip straight-line stubs, the frequency at the edge of a passband or stopband tends to be higher than the frequency determined by the filter synthesis theory. One of the reasons for this is thought to be the interconnection of a low-impedance straight-line stub and transmission lines. The length of a constituent transmission line cannot be determined precisely because of the finite width. Therefore, as a means of avoiding the frequency shift between a trial circuit and a theoretical one, we first introduce a radial-line stub, and then show the equivalency of a radial-line stub to a straight-line stub in a range of zero to the first resonant frequency from the view point of their input impedances. Dimensional data of radial-line stubs corresponding to low-impedance straight-line stubs are investigated with respect to examples of three-, five- and seven-element Butterworth and Chebyshev filters. It was found that frequency characteristics of trial lowpass filters using radial-line stubs agree well with theoretical characteristics known as the Butterworth or Chebyshev.

A novel periodic element for the sandwich photonic bandgap (PBG) structure named as H-shape element is presented in this paper. Sandwich PBG structure is a kind of PBG structure whose periodic lattice is buried in the midmost of the substrate. There's no requirement to drill or suspend the substrate. The new H-shape element is made of a central block connected with a long and narrow block on either side, and possesses a quite deep forbidden gap, whose width and depth can be tuned by varying the dimension of the central block. Theoretical results, as confirmed experimentally, indicate that the maximum insertion loss in the stopband is up to 80 dB. This sandwich microstrip structure can be constructed using conventional printed-circuit-board fabrication processes and integrated with other microwave components in a multilayered circuit. An improved notch filter with chirped central blocks is presented. The length of the filter is reduced by 16.7%, and the fractional bandwidth is increased by 8.1% compared with that of a conventional sandwich microstrip notch filter on the same substrate. The experimental results agree well with the finite difference time domain (FDTD) simulations.

In an attempt to enhance the impedance bandwidth and gain, a notched patch antenna is proposed that has a pair of L-strip feeders, and it has been experimentally studied. The enhanced features were confirmed and proved by comparing the proposed antenna with the antennae that have been reported in the relevant literatures. The experimental results showed that the impedance bandwidth (SWR2) of 35.74% and the peak gain of 8.69 dBi (at 2.17 GHz) were obtained by the frequency band under 2.5 GHz. Designed originally for PCS and IMT-2000 service band, the proposed antenna, with its simple structure, may easily be mass-produced and may have various commercial applications.

In transient analyzing of a crosstalk, the crosstalk waveform can be obtained with a commercial simulator such as SPICE simulation or FDTD (Finite Difference Time Domain) simulation. In case of using a simple model, a CMOS-IC load is considered as a constant capacitance load in crosstalk simulation. However, the semiconductor devices, such as CMOS-IC, have a characteristic of nonlinear impedance depending on the input voltage. We measured the far-end crosstalk of two parallel microstrip lines for a CMOS inverter (74HC04) load by changing the magnitude of the input step voltage. As the result, we found that the far-end crosstalk for the CMOS inverter load dose not necessarily depend on the input capacitance of the CMOS inverter.

This paper describes the design, fabrication, and measurement of a sequential-rotation microstrip-array antenna for Electronic Toll Collection System (ETCS). The ETCS is made possible by using roadside equipment with a radiation pattern that can accurately pinpoint the designated communication area, without interference from other lanes. The sequential-rotation microstrip-array antenna is designed and an absorber attached to the antenna is considered to reduce the side lobe level (SLL) for the antenna of ETCS. Results show that the antenna yields a return loss at a center frequency of -20.675 dB, an axial ratio of 1.15 dB, and a gain of 20.26 dBi.

We have devised and implemented a new low-loss microstrip transmission structure on LTCC substrate by including void cavities in the dielectric layer between conductor strip and ground plane. Measurements of λ/4 T-resonators with the novel microstrip structure reveal total loss of 0.0126dB/mm and Q-factor of 267 at 15.85GHz. The dielectric loss is analyzed as small as 0.0005dB/mm at the frequency, and that is equivalent to an improvement of a factor of 18 compared to the conventional LTCC microstrip structure. The proposed microstrip structure with the embedded void cavities is suited for low loss LTCC based RF-MCM applications.

As a typical planar antenna in Japan, a microstrip antenna and radial line slot antenna are chosen and some original technologies are introduced for them. About the microstrip antenna, the analyzing method is described first and the method based on the theory of microstrip planar circuit born in Japan is introduced. According to the formulas derived by this method, the design procedure considering the bandwidth is established. In addition, it is shown clearly that a microstrip antenna can produce the circular polarizations at two kinds of frequencies with a single feed. Furthermore, two kinds of broadband techniques born in Japan are picked up. About other unique microstrip antennas, they may be introduced in a suitable section each time. As for the RLSA, the history on invention is briefly presented. The radiation mechanisms depending on the slot-set arrangement and the excitation mode are discussed. The slot-coupling analysis to simulate the excitation of a two-dimensional uniformly-excited slot array is explained. The simple design based on the operation with traveling-wave propagation is also described. The technical progress to keep high efficiency in a wide gain range for satellite-TV reception is reviewed. Extensions of the RLSAs to millimeter-wave bands and plasma etching systems are finally summarized.

A four-pole quasi-elliptic function bandpass filter is designed and fabricated using a miniaturized microstrip square Stepped Impedance Resonator (SIR). The Nonuniform Finite Difference Time Domain (NUFDTD) method is used to design the resonator and to calculate the coupling coefficients of three basic structures. Theoretical and experimental results are presented. This filter is not only compact size but also has a wide upper stop band.

This study investigates the anisotropy substrate and dielectric cover effects of the rectangular microstrip patch antenna on anisotropy substrates with air gap, based on rigorous full-wave analysis and Galerkin's moment method. Results show that the resonant frequencies in the variation of air gap, patch length, and permittivity of superstrate can be determined and analyzed with varying dielectric cover thickness.

An efficient method for calculating impedance matrix elements is proposed for analysis of microstrip structures with an arbitrary substrate thickness. Closed-form Green's functions are derived by applying the GPOF method to the remaining function after the extraction of the contributions of the surface wave pole, source dipole itself, and quasi-static (i.e.real images) from a spectral domain Green's function. When closed-form Green's functions are used in conjunction with rooftop-pulse subsectional basis functions and the razor testing function in an MoM with an MPIE formulation, the integrals appearing in the calculation procedure of the diagonal matrix elements are of two types. The first is x0n [e^(-jk0(x02 + y02 +a2)1/2)/(x02 + y02 +a2)1/2)]dx0dy0 (where n=0, 1) for the contribution of both the source dipole itself or real images where a=0 and complex images where a=complex constant, while the other is x0n H0(2)(kρp (x02 + y02)1/2)dx0dy0 for the contribution of the surface wave pole where kρp is a real pole due to the surface wave. Adopting a polar coordinate for the integral for both cases of n=0 and n=1 and performing analytical integrations for n=1 with respect to the variable x0 for both types not only removes the singularities but also drastically reduces the evaluation time for the numerical integration. In addition, the above numerical efficiency is also retained for the off-diagonal elements. To validate the proposed method, several numerical examples are presented.

Microstrip antennas with meshed ground planes are suitable for radiation elements of large satellite phased array antennas. Although they have some mechanical advantages such as the possibility of antenna weight reduction, they also cause electrical problems such as the resonant frequency shift and F/B ratio degradation. The first purpose of this paper is the analytical understanding of the resonant frequency shift, for which two perturbational methods are proposed. One has a closed form expression that provides some useful design data. The other is to solve the integral equations by using the periodicity of the meshed ground plane, which gives more accurate results. The second purpose of this paper is to investigate the backward radiation from the meshed ground plane analytically, for which we derive an analysis method from the calculated results of the resonant frequency shift. The proposed methods are verified with the measured ones.

In general, the attenuation characteristics of band-pass filters can be improved by generating attenuation poles in the stop band. In this paper, a design method for a planar band-pass filter with attenuation poles based on a half-wavelength resonator is proposed. According to this design, the attenuation poles can be obtained at any desired frequency by means of coupling structures. Two kinds of filter with the characteristics of steep skirt and wide stop-band were designed and fabricated with the result that the validity of the design method was demonstrated. Therefore, a filter with excellent attenuation characteristics for various applications can be achieved.

We propose a new type of microstrip line to waveguide transition fabricated on a single layer dielectric substrate. Impedance matching of the transition is achieved by controlling the size of a matching element and the length of an inserted microstrip line across a waveguide. As a result of experiments, low transmission loss of 0.4 dB is realized at the design frequency of 76.5 GHz. Bandwidth of the transition is numerically investigated by the finite element method. It is clarified that the bandwidth of the transition becomes wider as the cross section of the waveguide becomes smaller and twice as wide as that of a conventional microstrip patch antenna element fabricated on a dielectric substrate with the same parameters. In addition, the effect of errors in relative position between the dielectric substrate and the waveguide is also investigated. It becomes clear that degradation of transmission characteristics is caused by the shift of resonant frequency and keeps less than 0.1 dB for a manufacturing accuracy within 0.1 mm.

The measurement sensitivity of microwave surface resistance, Rs, of high temperature superconducting (HTS) thin films using half-wavelength microstrip resonator with copper and HTS ground plane is analyzed for fundamental and higher order modes of the resonator. The estimated sensitivity of Rs-measurement is at least an order of magnitude greater at fundamental resonant frequency compared to when measured using higher order harmonic modes.

We report recent achievements in interfacing Josephson junction circuits with superconductor MicroStrip Lines (MSLs). We studied basic techniques that allow satisfactory operation of different devices with MSLs. Successful operation of the interfaces with very low error rate has been demonstrated even at the MSL resonant frequency.

A dual-offset microstrip-fed slot antenna having large bandwidth studied in this paper. The proposed antenna is analyzed by the Finite Difference Time Domain (FDTD) method. In this case, two offsets and other design parameters of the antenna lead to the good impedance matching over a wide frequency band. The experimental bandwidth is approximately 1.587 octave (-10 dB S11). And the experimented data for the impedance loci, the radiation patterns, and gain of the antenna are also described. The measured results are relatively in good agreement with the FDTD results.

A simulation tool for analyzing circuit characteristics of microstrip-type MIC (Microwave Integrated Circuit) passive elements is presented. The major part of this tool is the electromagnetic wave analysis based on the FD-TD (Finite-Difference Time-Domain) method combined with the mode expansion theory. Although the element structures which can be treated in this tool are limited to only less than ten fundamental structures in the present stage, its extension to the more versatile tool applicable to other various element types is rather straightforward and simple in principle. When using this tool, we first choose the element configuration to be calculated and give, on a panel, necessary parameter values related to calculation range and mesh division scheme. Given these values, the first step calculation starts to obtain the characteristic impedance, cross sectional field distribution of the propagating mode, etc. of the basic microstrip line. Field distributions around the element configulation are calculated next with the mode field oscillation being given. Through this process the field distributions on a closed rectangular parallelepiped surface enclosing the element configuration are stored in files, from which S parameter and radiated fields are calculated by invoking the reaction integral with propagation modes and radiation modes, respectively. The results obtained in these three steps can be expressed, at our discretion, as line drawings or two-dimensional density plots.

The diffraction problem of a Gaussian beam by finite number of periodic slots in a parallel-plate waveguide filled with a homogeneous dielectric is considered. The integro-differential equation for the unknown equivalent surface magnetic current density over the slots is derived and solved by the method of moments (piecewise sinusoidal Galerkin method). From some theoretical results for the angular diffraction pattern, the present geometry is observed to simulate well the previous rectangular groove geometry from the viewpoint of scattering behaviour. In addition, two types (resonance and non-resonance types) of Bragg blazing phenomena are discussed. Simultaneous Bragg and off-Bragg blazing is also demonstrated.