Electrically-Small Circularly-Polarized Quasi-Yagi Antenna

Abstract

Abstract-In this letter, an electrically-small circularly polarized (CP) quasi-Yagi antenna is presented. It is composed of three elements; i.e., a compact single-feed crossed-dipole antenna acted as the driver and two parasitic elements acted as the reflector and director, respectively. Each arm of all elements contains a meander line with an arrowhead ending to realize compactness. The driver has double vacant-quarter printed rings incorporated into it to generate the CP radiation. The parasitic elements are incorporated with the crossed-dipole driver to not only produce a directive radiation, but also broaden the antenna bandwidth. The final design with overall size of 35 mm × 35 mm × 27 mm (0.184λ o × 0.184λ o × 0.142λ o at 1.575 GHz, ka = 0.93) a measured 10-dB bandwidth of 19.23% (1.476-1.790 GHz), 3-dB axial ratio bandwidth of 7.67% (1.505-1.625 GHz), a broadside gain of 3.0 ± 0.2 dBic, and the maximum front-to-back ratio of 8.2 dB. The proposed antenna is applicable to a variety of wireless system operating near 1.575 GHz, such as Global Positioning Systems, Global Navigation Satellite Systems, as well as international maritime satellite organization (Inmarsat) networks.

High-Isolation Wide-Beam Dual-Polarized Antenna Utilizing Symmetrical Feeding

“…A performance comparison between the proposed antenna and the related priors is given in Table 2. Firstly, as compared to most antennas with single-ended feed scheme [4][5][6][7][8][9][10][11][12][13], the proposed antenna yields a significantly higher isolation, comparable overall-size, and bandwidth. Secondly, the proposed antenna achieves a similar isolation, but a simpler feeding structure, related to the double differentialfeed designs [17][18][19].…”

“…The feeding structure is an integrated balun, which consists of a Γ-shaped microstrip-line coupled to a coplanar-stripline. This type has been widely utilized in several previous dual-polarized printed dipoles, e.g., see [11]. The unbalanced structure of the balun degrades the port-to-port isolation, and consequently, antennas utilizing this feeding only achieved an isolation up to about 30 dB [9][10][11].…”

“…This type has been widely utilized in several previous dual-polarized printed dipoles, e.g., see [11]. The unbalanced structure of the balun degrades the port-to-port isolation, and consequently, antennas utilizing this feeding only achieved an isolation up to about 30 dB [9][10][11]. This is because when the other orthogonal dipole similar to Fig.…”

“…Moreover, to achieve pervasive coverage, different techniques have been presented to widen the beamwidth of the dual-polarized antenna. The techniques, for instance, include adding parasitic elements [9], tetrahedral ground [10], cavity [11], notched wall [12], and via fence [13].…”