A magnetic corrugated horn antenna system is disclosed. This system includes a magnetic hybrid-mode horn antenna composed of a circular waveguide and a corrugated horn antenna which has a thin magnetic coating on its inner wall. The corrugation of the conical horn helps it to produce equal E-plane and H-plane patterns with low sidelobes. The magnetic coating can enhance or duplicate the beneficial effects of the corrugation, while avoiding the high gain loss and poor patterns reported in prior art systems that relay only on corrugated horns.

Magnetic hybrid-mode horn antenna

The radiation from a rectangular waveguide with a lossy flange coating is studied both analytically and experimentally. An analytic method using Fourier analysis and an impedance boundary condition is proposed. The experiment was performed using a flange covered with a rubber ferrite sheet at an X-band frequency. The numerical and measured results agree well and show that the lossy flange improves the E-plane radiation pattern and the crosspolar radiation. A boresight gain drop of about 2 db is predicted theoretically and measured experimentally. >

Radiation from a rectangular waveguide with a lossy flange

Cavity-backed slot (CBS) antennas are commonly used in Earth-based and space-borne applications. In this manuscript, the finite-difference time-domain (FDTD) method is used to analyze different antenna characteristics of such elements including input impedance, coupling, and radiation patterns. Emphasis is given to coupling calculations, especially to different methods to reduce coupling. Specifically, coupling reduction is attempted using lossy material superstrates or ground plane discontinuities, such as slits. Numerical issues concerning the analysis of CBS antennas in the context of FDTD are also discussed.

Coupling modeling and reduction techniques of cavity-backed slot antennas: FDTD versus measurements

A wireless communication device includes an antenna (600g) configured with two conductive elements (601/602) separated by an insulating medium (603). One conductive element (602) is a ground plane and the other is a microstrip line (601). The ground plane (602) is formed with a bend (644) proximate an end. The microstrip line and the ground plane exhibit a characteristic impedance that may vary along the length of the microstrip line. The separation distance of the microstrip line (601) from the ground plane (602) is changed to reduce the resonant frequency of the microstrip line.

Methods and apparatus for implementation of an antenna for a wireless communication device

An electric conducting surface coated with a thin, lossy magnetic layer has been both theoretically and experimentally observed to be equivalent to a surface that is conducting to both electric and magnetic fields of plane waves at near-grazing incidence angles. This dual conductivity phenomenon has been utilized to design horn antennas for desired performance characteristics such as symmetric beams, low sidelobes, and low cross polarization. The effects of this surface are in many ways similar to those of the corrugated conducting surface. However, this coated surface appears to have a broader spectrum of applications in other antennas and microwave devices because of its apparent dual (electric and magnetic) conductivity. >

The magnetically coated conducting surface as a dual conductor and its application to antennas and microwaves

It is shown that a circular waveguide horn coated with a lossy material in its interior wall can be used as an alternative to a corrugated waveguide for radiating a circularly polarized (CP) field. To achieve good CP radiation, the diameter of the structure must be larger than the free-space wavelength, and the coating material must be sufficiently lossy and magnetic. The device is cheaper and lighter in weight than the corrugated one. >

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D. W. Justice

Papers

A simple circular-polarized antenna: circular waveguide horn coated with lossy magnetic material