Meander Antennas.

Abstract

Meander antennas are a new class of wire structures made from meander sections intended to reduce the resonant length of the antenna. Each half section is formed when the wire is folded three times over its course and a complete section is made when two half sections are connected back-to-back. The resonant frequency and other antenna characteristics depend primarily on the number of sections per wavelength N and the separation of the folded arms w. Usually w is kept small in comparison to the length of the antenna and therefore the undesirable radiation due to the horizontal portions are negligible. In this case the reduction in the resonant length depends on N and is typically 25 to 50 percent. The efficiency is affected only by the ohmic losses in the wire and the b and width of the antenna is generally less than a conventional monopole but comparable to that of other size reduction techniques such as base loaded antennas. When N increases the resonant resistance increases and so does the resonant frequency (less size reduction) however the b and width of the antenna improves. For a constant N, when w is increased the size reduction is enhanced but the b and width decreases. The experimental results on resonant resistance, resonant frequency and the percentage of size reduction are in close agreement with the numerical analysis. The current distribution on the antenna is obtained and compared for several different me and er geometries. The current distribution has a marked peak near the feeding point while the phase is relatively constant along the entire antenna. The effect of wire radius on the antenna characteristics and the effect of w on the pattern of the antenna are also investigated. A log-periodic me and er dipole array and a folded me and er monopole are studied experimentally with satisfactory results as an illustration of the applications. Many variations of me and er structures are also shown to have size reduction potentialities.