A Hybrid Approach for Receiving Antennas: Concepts and Applications
Résumé
The long-standing problem of constructing an accurate equivalent circuit for receiving antennas by handling both the absorbed and scattered powers for all kinds of antennas, is addressed. By combining the electrical properties of the antenna with its radiating and scattering characteristics, it is shown that the input impedance, radiation pattern and vectorial effective height are three essential parameters to which the open-circuit scattering parameter (new) should be added. The antenna's power budget is then established and applied to various kinds of antennas. Theoretical results showed a perfect agreement with the method of moment (MoM) and the finite integration technique (FIT) over a large frequency-range under various conjugate-matched loads. It comes out that good radiating antennas are good scatterers as well but, without a precise power budget calculation, it is not evident to predict whether an antenna would absorb more or less than it scatters. Thin-metallic structure directive antennas (TMSDA) appear to be the best candidates to absorb more than they scatter under matching conditions. The two-element Yagi antenna can reach an absorption efficiency of 65%, while the pyramidal horn achieves only 12% maximum. The dipole is confirmed at 50%-absorption efficiency.