Paolo Bielli

Analysis and Synthesis of Corrugated Conical Horns

The characteristics of corrugated conical horns, radiating the balanced hybrid mode HE11 have been summarized in a number of linear curves giving the beam width at different levels versus the horn flare angle (2¿) and versus the radius of the horn aperture, normalized to the wavelength (¿ = r/¿). Moreover the feed horn performance for single or double reflectors antennas, have been analysed and curves are presented for the antenna illumination efficiency (aperture efficiency by spillover efficiency) versus parameters d and a. All the curves reported are a useful basis for the antenna design and give a fast and accurate solution to the following problems: - synthesis of a corrugated conical horn with a specified amplitude radiation pattern - synthesis of a corrugated conical horn as a function of the antenna illumination efficiency.

Design and Measurement of Frequency Selective Surfaces

A new method for dimensioning a multiple layer Frequency Selective Surface (F.S.S.) based on an appropriate electromagnetic model will be examined. Feasibility and performance I imitations of F.S.S. having a single grid of Jerusalem crosses packed with several dielectric slabs will be analyzed. The technique of waveguide simulators is proposed as an attractive alternative to the radiation measurement technique. Experimental and theoretical results, in the frequency range of 8÷18Qk, are discussed in order to point out: the val idity of the measurement technique and the accuracy of the electromagnetic model.

2-11 GHz Dual Polarization Antenna for Terrestrial Radio Links

The paper presents the design criteria and the electrical characteristics of a terrestrial radio link antenna operating simultaneously, with dual linear polarization, at 2 and 11 GHz frequency bands. The antenna consists of a 4m parabolic reflector with a double grid shaped dichroic subreflector which is the most innovative component, theoretically designed and optimized by means of a reliable electromagnetic model. The performance are comparable with the typical values of radio link antennas operating at single band. Both electrical and cost requirements have been considered in the choice of the candidate configuration.