Equivalent circuit model for top-loaded folded monopole of extremely low profile

Abstract

In this article, a concise equivalent circuit model for top‐loaded folded monopole antenna (TLFMA) of low profile is presented. The TLFMA has one driven post and one shorting post, loaded with a circular conducting plate on the top, which can achieve a very low profile with a good radiation resistance. The equivalent circuit consists of two models, which are transmission‐line mode and antenna mode. The impedance of TLFMMA can be easily get from this equivalent circuit model. The accuracy of the presented equivalent circuit model has been verified by the simulation and measurement results.

Narrow transverse‐size compact vertically polarized end‐fire antenna using dual‐hat composite elements

“…A equivalent antenna model of the quasi-Yagi array antenna model (antenna 3) in Figure 2 was firstly extracted as shown in Figure 3A for easy analysis. Similar to numerous analyses in the references, 17,19 the understanding of the antenna model in Figure 3A can be implemented in terms of an equivalent circuit, this is shown in Figure 3B.…”

“…To calculate the values of the passive components of the circuit in Figure 3B, it may find their calculation expressions in terms of transmission-line and antenna theory. 15,17 3 | NARROW TRANSVERSE-SIZE COMPACT VERTICALLY POLARIZED END-FIRE ANTENNA…”

“… is static capacitance and the composition of can be expressed as . Among that, refers to the parallel‐plate capacitance due to the top hat and the ground plane, and is the capacitance introduced by the vertical posts 17 . Input impedance is primarily obtained in terms of a shorted‐circuited two‐wire transmission line mode.…”

“…Actually, the top hat patches are permitted a large degree of design freedom because the shorting posts are served as the main radiator. 17 For a quasi-Yagi array design, twoelement array has received increasing interests because the increase of the director element number generally has weaker influence on the end-fire gain. 18,19 Therefore, paying more attention to the design of the reflector element has become a flexible way to create a narrow transverse size, end-fire radiation and other good performance.…”

“…Possible solutions for such an element design can be implemented by using top‐loaded 13,14 or folding techniques, 15,16 with the top‐loaded manner the top hat of capacitive characteristics can compensate for the inductance of the connected post. Actually, the top hat patches are permitted a large degree of design freedom because the shorting posts are served as the main radiator 17 . For a quasi‐Yagi array design, two‐element array has received increasing interests because the increase of the director element number generally has weaker influence on the end‐fire gain 18,19 .…”