Design and Testing of Simple, Electrically Small, Low-Profile, Huygens Source Antennas With Broadside Radiation Performance

Abstract

The efficacy of a simple, electrically small, low-profile, Huygens source antenna that radiates in its broadside direction is demonstrated numerically and experimentally. First, two types of electrically small, near field resonant parasitic (NFRP) antennas are introduced and their individual radiation performance characteristics are discussed. The electric one is based on a modified Egyptian axe dipole NFRP element; the magnetic one is based on a capacitively loaded loop (CLL) NFRP element. In both cases the driven element is a simple coax-fed dipole antenna, and there is no ground plane. By organically combining these two elements, Huygens source antennas are obtained. A forward propagating demonstrator version was fabricated and tested. The experimental results are in good agreement with their analytical and simulated values. This low profile, ~ 0.05 λ 0 , and electrically small, ka = 0.645, prototype yielded a peak realized gain of 2.03 dBi in the broadside direction with a front-to-back ratio (FTBR) of 16.92 dB. A backward radiating version is also obtained; its simulated current distribution behavior is compared to that of the forward version to illustrate the design principles.Index Terms -Broadside directivity, electrically small antennas, Huygens source, low profile, metamaterial-inspired structures, near field resonant parasitic antennas.

The directivity of a compact antenna: an unforgettable figure of merit

“…Even though this quite electrically small, broadside radiating Huygens source system exhibits some sensitivity to its design parameters, slightly larger related designs have been successfully fabricated and measured, confirming the concepts [23]. Moreover, even though a very narrow bandwidth occurs, which arises from the required overlap of two high Q resonators (i.e., the electrically small NFRP elements), it has been demonstrated that by introducing appropriate non-Foster reactances into the NFRP elements, interesting bandwidths can be obtained, while maintaining the desired Huygens source behavior [24].…”

“…The previously discussed cases have provided further insights into the electrically small, low-profile broadside radiating, Huygens source antennas [22][23][24]. The configuration of interest is shown in Figure 19.…”

“…On the other hand, recent designs have suggested that Huygens sources may be advantageous, particularly in regards to their FTBR values [20][21][22][23][24][25]. Consequently, it was explored whether or not the magnetic-based EZ antenna could be augmented with an electric-based NFRP antenna to achieve an electrically small Huygens source.…”

“…These include, for example, end-fire arrays [5][6][7][8], electromagnetic band-gap (EBG) structures [9], high impedance surfaces and artificial magnetic conductors [10][11][12][13], nearfield resonant parasitic (NFRP) elements [14][15][16], nonFoster circuit-augmented antennas [17], two-element NFRP antenna arrays [18,19], and Huygens sources [20][21][22][23][24][25]. The metamaterial-inspired NFRP antenna designs have led to the realization of many performance enhancements of compact systems.…”

Electrically-Small Circularly-Polarized Quasi-Yagi Antenna

“…In order to address this issue, several ways of developing directive ESAs have been proposed. These ways, for instance, include: using electrically small reflectors [3][4][5] or directors [6], associating with ground plane [7,8], arranging ESA elements in linear array [9], and constructing Huygens source antennas [10][11][12]. On the other hand, it well known that circularly polarized (CP) radiation has been used to combat multi-path interferences or fading, mitigate polarization mismatch losses, and reduce Faraday rotation effects caused by the ionosphere.…”