Experimental studies of the backward wave oscillator with a ”grid” diffraction grating that is formed by a periodic set of metallic threads inside a rectangular waveguide are proceeded with study of the generation intensity as a function of the grating length.

We describe an experimental and theoretical characterization of rectangular resonant cavities integrated into parallel-plate waveguides, using terahertz pulses. When the waveguide is excited with the lowest-order transverse-electric mode, these cavities exhibit resonances with narrow linewidths. Broadband transmission spectra are compared with the results of mode-matching calculations, for vari...

One of the problems of the finite element and the finite difference method is that as the dimension of the problem increases, the condition number of the system matrix increases as @(l/hz) (of the order of hz, where h is the subsection length). Through the use of a suitable basis function tailored for rectangular regions, it is shown that the growth of the condition number can be checked while ...

In this paper, the characteristic equations of the E mn and Ex mn modes of the dielectric rectangular waveguide have been derived using the mode matching technique. No assumptions have been taken in the derivations which have been straight forwardly done. Two ratios have been introduced in the characteristic equations and the new set of characteristic equations thus obtained are then plotted an...

The electrodynamical properties of a volume resonator formed by a perodic structure built from the metallic threads inside a rectangular waveguide (”grid” volume resonator) is considered for travelling wave tube and backward wave oscillator operation. Peculiarities of passing of electromagnetic waves with different polarizations through such volume resonator are discussed.

The transverse operator method is used for the analysis of an open-ended rectangular waveguide, in particular as a radiating element. It is shown that the method allows a systematic formulation of problems involving discontinuities whether they are radiating or not. The numerical results concerning the admittance and power patterns of a waveguide aperture surrounded by an infinite conducting fl...

First observation of generation in the backward wave oscillator with a ”grid” diffraction grating and lasing of the volume FEL with a ”grid” volume resonator that is formed by a perodic set of metallic threads inside a rectangular waveguide is considered.

This paper presents statistical signal processing approaches for clutter reduction in Stepped-Frequency Ground Penetrating Radar (SF-GPR) data. In particular, we suggest clutter/signal separation techniques based on principal and independent component analysis (PCA/ICA). The approaches are successfully evaluated and compared on real SF-GPR time-series. Field-test data are acquired using a monos...

In the millimeter-wave bands, the series-fed array antenna is facing a problem of large transmission loss and narrow bandwidth by using a high permittivity and large-loss tangent material. In this report, an air-layer is inserted in a LTCC waveguide of εr=6.6 and tanδ=0.013 to reduce the transmission loss. The reduction of the equivalent dielectric constant by the air insertion structure enhanc...

Fabrication process of multimode 1 x 2 optical rectangular planar power splitter suitable for low-cost short distance optical network is presented. The splitters were designed by beam propagation method for standard input/output plastic optical fibre. Materials used for the splitter were: UV acrylate photopolymer polymer or epoxy resin for optical core waveguide layers and Y-groove substrate fo...