Short- or open-circuited dipole parallel to perfect reflector plane and embedded in substrate and acting at resonance

The properties of an open or short-circuited flat resonant dipole parallel to a reflector plane and embedded in a substrate are given. Simple transmission-line model analysis is used. Correct agreement is obtained between theoretical and experimental results, and literal formulas for radiation resistance and bandwidth are thus justified. To a first approximation, the radiation resistance is independent of the substrate, whose effect is to reduce the length and the bandwidth of the radiating dipole.     

Large-bandwidth flat cylindrical array with circular polarisation and omnidirectional radiation

Experimental properties of a flat cylindrical array with circular polarisation and omnidirectional radiation are presented. The thickness of the array wrapped on a perfect conducting cylinder is 0.04?0. A bandwidth of 10% has been obtained. It is now possible to decrease the thickness by a factor 2 (i.e. to 0.02?0), when using a short-circuited elementary source instead of a flat folded dipole, and yet retain the same band-width.     

Log-periodic flat short-circuited dipole array with a squinted beam

A new class of microstrip travelling wave antenna of large bandwidth is described. The log-periodic array is composed of flat short-circuited half dipoles acting at quarter-wave resonance and fed in series by means of a high characteristic impedance microstrip line. A model has been constructed and tested. A large squinted main beam is obtained between 0.75 and 4.5 GHz. The constant experimental radioelectric properties are in good agreement with the theoretical predictions.     

Flat short-circuited strip of one wavelength width and acting at quarter-wave resonance

Properties of a large, flat short-circuited half-radiating strip acting at a quarterwave resonance are presented. It is excited by means of several feed points. The obtained bandwidth is large. When the width is about one wavelength, it appears as an antenna with excellent efficiency and high directivity. Correct agreement is obtained between theoretical and experimental results.