ANALYSIS OF SOFT AND HARD STRIP-LOADED HORNS USING A CIRCULAR CYLINDRICAL MODEL

Strip-loaded horns with transverse (soft) and longitudinal (hard) strips are analyzed theoretically. The method is based on a circular cylindrical and uniform waveguide model with a periodic strip structure. The field is represented by an infinite series of space harmonics (Floquet modes) in the air-filled central region and in the dielectrically filled wall region. The tangential field is forced to be continuous across the air-dielectric boundary. The propagation constant and the total field (including the hybrid factor) can be determined by solving the resulting matrix equations. The convergence of the solution has been accelerated by calculating the higher order terms analytically. It has been shown that the soft strip-loaded horn in principle exhibits the same electrical behavior as a corrugated horn. The horn represents an interesting alternative to the corrugated horn in wideband or dual-band applications, in particular for millimeter waves and for lightweight applications onboard satellites. The hard strip-loaded horn has potentially high gain and low cross polarization over a certain frequency range, dependent on the horn dimensions, thickness of the dielectric wall and on how strong the stripline modes are being excited. This horn may be used in cluster feeds to reduce spillover across the reflector, and in limited scan arrays to reduce size, weight, and complexity. © 1990 IEEE