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ABSTRACT Circular waveguides loaded with shaped dielectric rods are studied. The waveguide is entirely filled with a dielectric rod, extended from the waveguide aperture and conically shaped to modify the aperture distribution. Its performance as a primary feed is investigated, without and with quarter-wavelength chokes, to improve sidelobe and backlobe levels. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1568-1573, 2015 [ABSTRACT FROM AUTHOR]

ABSTRACT Radiation characteristics of dielectric loaded circular waveguide feeds are investigated and a design procedure is outlined. For a given waveguide radius, the radiation pattern equalization is achieved by adjusting the extended dielectric length from the aperture. A prototype is designed, fabricated, and studied in the laboratory, validating the design procedure. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1432-1438, 2015 [ABSTRACT FROM AUTHOR]

In this article, we present a study dealing with the design, optimization, and manufacturing of different versions of a broadband monopole antenna with a convex conical reflector. These antennas are created by a wire monopole that is placed into the axis of a convex conical reflector. The principle of antennas is based on the transformation of the impedance of a coaxial transmission line to the open space impedance via a circular waveguide. The results of simulations performed in CST Microwave Studio are mutually compared. Then, the simulated versions of broadband monopole antennas were optimized with respect to specified objectives. According the available materials, we built selected versions of the antenna and experimentally verified their properties. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1243-1247, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27598 [ABSTRACT FROM AUTHOR]

A method is presented that incorporates thin, lossy layers into a finite-difference frequency-domain algorithm designed for structures with circular geometry. The method allows the grid spacing to be much larger than the thickness of the thin layers. This greatly reduces the computational effort required when simulating circular structures such as optical fibers that incorporate thin layers. The method is validated by a comparison with the analytical solutions. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 453–457, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21378 [ABSTRACT FROM AUTHOR]

In this paper, a new spatial-images procedure has been applied to the analysis of microstrip-to-circular waveguide transitions. The numerical technique is based on the utilization of stratified image rings, from which the weights and orientations of either discrete charges or dipole images are determined. This is accomplished by enforcing the scalar and vector potentials' boundary conditions on the cavity walls. The results obtained with the new Green's functions have been compared to those given by a standard integral-equation method based on the free-space Green's functions, and a finite-element implementation. Good agreement is shown between the different techniques, thus demonstrating the usefulness of the new approach. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 563–568, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20881 [ABSTRACT FROM AUTHOR]

An efficient technique to locate minima (zeros) in the smallest singular value of a singular value decomposition, as used to solve eigenvalue problems in electromagnetics, is presented. The efficiency of the technique depends only on the availability of a sufficiently accurate representation of the smallest singular value; the sharpness of the peaks is of minor relevance. The technique is applied to determine the cutoff wave numbers of a ridge circular waveguide to demonstrate its efficiency. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 14: 318–321, 1997. [ABSTRACT FROM AUTHOR]

The scattering optimization method is utilized to design compact circular waveguide mode converters, which are compared with some earlier designs. This approach is used to design a TE11 to TM11 mode converter at 9.94 GHz, which was subsequently fabricated with easily available components. At this frequency, the purity of the TM11 mode at the output of the mode converter was measured to be 98.1%, which is very close to the theoretical value of 99.5%. [ABSTRACT FROM AUTHOR]

A simple expression for the length of a dielectric ring or rod resonator in a cutoff circular waveguide is given. Instead of using a determinant equation to design the resonator, it is only required to determine the phase of the reflection coefficient of the resonating mode at a step discontinuity between an infinitely long rod or ring and an infinitely long cutoff waveguide. The technique is validated by comparison to an analytical solution, as well as previously published results from the literature. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 23: 203–205, 1999. [ABSTRACT FROM AUTHOR]