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Including space harmonics in the interior region of the waveguide, the fields radiated by a $$ HE^{{{\left( 1 \right)}}}_{{11}} $$ mode in an aperture of a corrugated groove conical horn are described, and theoretical radiation patterns of the horns are given. Experimental results in support of our theory have also been presented.

In this paper, finite-difference time-domain (FDTD) method is used to calculate the driving-point impedance of radial transmission-line in circular groove guide. A simple way is used to approximate the curvilinear metal boundary of circular groove guide. And perfectly matched layer (PML) is applied on the open boundary of circular groove guide. Fine-grid is used to calculate the EM fields in the radial transmission-line in which we are interest. Discretized wave equation is used to update the tangential electric field on the boundary of coarse- and fine-grid. At last, the driving-point impedances related to different diameter of the radial transmission-line are obtained from the ratio of the Fourier transform of the voltage to the Fourier transform of the current.

In this paper, a new type of W band circular waveguide Y-junction circulator is presented. The structure of this type of Y-junction is a cylindrical cavity connecting with three circular waveguides. The performances of the type of circulator are analyzed by the edge-based vector finite element method hybridized with the modal expansion. The numerical results show that this type of waveguide Y junction circulator has good circulation performance.

Finite-difference time-domain (FDTD) method is used to calculate the driving-point impedance of the circular groove guide diode mount. A simple way is proposed to approximate the curvilinear metal boundary of circular groove guide. Discrete equations are obtained from the Ampere's law and Faraday's law. Perfectly matched layer (PML) is applied on the open boundary of circular groove guide. At last program is made to obtain the field components. The driving-point impedance can be achieved from the ratio of the Fourier transform of the voltage and the Fourier transform of the current. The cutoff frequency and field pattern of the dominant mode are also obtained with well agreement with the theoretical results, this verifies the validity of the FDTD program.

By using method of space harmonics in the interior and higher order modes in the slot region of the corrugated circular groove waveguide, The dispersive equation of this waveguide is derived.

The structure of circular groove guide coupled with high-Q cavity is studied. As a new type of millimeter wave component, it can be used for wavemeter and highly stabilized circular groove guide oscillator. The design and analysis of the novel structure are given in this paper.

This paper presents an instance of using FD-TD method to analyze the aperture field of circular groove guide horn antenna. This process is one part of a hybrid method to solve the radiation field of aperture antenna. To verify the calculated aperture field the radiation pattern is computed from it and compared with the measured one. Good agreement is reached.

Using the mode matching technique and neglecting the space harmonics, the characteristic equation of corrugated circular groove guide is given.

When the periodic spacing of corrugated wavesguides is much less than wavelength λ, the slot width d≈L, and the space harmonics are neglected, the characteristic equation of corrugated square groove waveguides is formulated based on Maxwell's equations and boundary conditions.

When neglecting space harmonics and higher-order slot modes, the attenuation characteristic of corrugated circular groove waveguide has been investigated. It is shown that under certain conditions, the attenuation coefficient of HE11 mode will be lower than that of dominant TE(1)11 mode of circular groove waveguide with same radius.

A rectangular to circular groove waveguide transition is described in millimeter-wave band. The transition maintains a constant cutoff wavelength. Using the Finite Element Method, the size of the variable cross-section throughout the transition are calculated and the transition is designed.

Using the Fourier transform and the mode matching technique, the circular groove guide is analyzed. While deriving a series of simultaneous equations basing on boundary conditions, we get the characteristic equation of this guide structure that is strict than those before. The numerical result shows that the approach presented in this paper has a good precision.

This paper gives a structure on the mode converter from TE 0n O mode of gyrotron output to the main mode of the circular groove guide. The design consists of two parts: the first part is to convert TE 0n O to TE 01 O using an advanced periodic wall perturbation technology, the second part is to convert TE 01 O to mode basing on the method of gradually changing the wave guide cross section. An example at 37.5Ghz is given. For the first part, the efficiency is 94.71%, the length is 1.868m. For the second part, the theoretic figure of reflectance coefficient vs. frequency is given.

A novel horn antenna for millimeter waves based on circular groove guide is presented and investigated in this paper. Its radiation patterns are calculated by employing the aperture field method. The patterns obtained by experiment show agreement with calculated results.

A novel structure for the transition from the dominant mode in circular waveguide to that in circular groove guide is presented. The mode converter based on this structure which has low reflection coefficient is designed. The numerical result shows that the performance of this new type of transducer is improved.

A novel method for solving arbitrary cross-sectionn waveguides is presented. The novel method is a modification of the eigen-weighted boundary integral equation method; the EWBIEM is modified by using the eigenfunction of a fictitious regular boundary as weighting function, whose eigenvalue may be the known value, and meanwhile using the domain-bases. To confirm the validity of the novel method, numerical analysis are presented for circular groove guide as an example.

Double circular groove guide is a simple structure which can be used to construct directional coupler. In this paper, the coupling property of two uniformly coupled circular groove guides is studied based on the transverse resonance analysing results of closed double circular groove guide.

The dispersion characteristics of symmetrical and asymmetrical double circular-groove guide are analyzed by using the method of weighed residuals (MWR) and the theoretical performance of the directional coupler based on double circular-groove guide is also presented.

Circular groove guide is a kind of waveguide for millimeter waves with low loss, large dimensions, and low dispersion. In this paper, the dominant mode characteristics of it is analysed. The technique that mode macthing method combines with point matching method is used to derive the Nth-order characteristic equation of the guide. The 1st order, 2nd order and 3rd order approximate curves that the normalized cutoff wavelength of circular groove guide varies with c/a are given. The attenuation curves are given at 1mm, 1.5mm and 3mm wavelength. The numerical results are in well agreement with the experimental results published.

The structure of closed circular groove guide is similar to that of open circular groove guide, but it can prevent energy from leaking out of the guide. In this paper, the dominant mode in closed circular groove guide is considered. The characteristic equation is derived and solved and the results are discussed.

The variations in propagating characteristic of circular groove guide due to tolerance are analyzed by using eigen-weighted boundary integral equation method (EWBIEM). Theoretical analysis and experimental results show that as long as the tolerance of circular groove guide is not very large the variations in characteristic of circular groove guide are very small.

A transition between rectangular waveguide and circular groove guide is described. The composite transition consists of two sections. It is theoretically designed to provide both mode matching as well as low reflection coefficient. The performance of the transducer is plotted.

According to the analyses of the moding properties of circular groove guide, the guide dimension for single mode operation is determined. Our results show that circular groove guide has the advantage of wide band.

The circular groove guide is one of several waveguides that will widely be used at millimeter and submillimeter waveband. The leaky antenna based on the circular groove guide is studied by the method based on a transverse equivalent network in this paper.

When the circular-groove guide is closed at the two side ends by metal, its dispersion characteristic is studied in this paper, and theoretical values are presented. The eigen-weighted boundary integral equation method was used here.

The characteristic equations of higher-order modes, including TE mode and TM mode, are derived in this paper. These equations are very useful for us to understand the mode distribution in circular groove guide.

In order to get a better understanding of the coupling properties of asymmetric double circular groove guide, the characteristic equation of this structure has been solved and its theoretical curves has been given and discussed.