Broadband Circularly Polarized Crossed Dipole With Parasitic Loop Resonators and Its Arrays

Abstract

A novel printed crossed dipole with broad axial ratio (AR) bandwidth is proposed. The proposed dipole consists of two dipoles crossed through a 90 phase delay line, which produces one minimum AR point due to the sequentially rotated configuration and four parasitic loops, which generate one additional minimum AR point. By combining these two minimum AR points, the proposed dipole achieves a broadband circularly polarized (CP) performance. The proposed antenna has not only a broad 3 dB AR bandwidth of 28.6% (0.75 GHz, 2.25-3.0 GHz) with respect to the CP center frequency 2.625 GHz, but also a broad impedance bandwidth for a voltage standing wave ratio (VSWR) 2 of 38.2% (0.93 GHz, 1.97-2.9 GHz) centered at 2.435 GHz and a peak CP gain of 8.34 dBic. Its arrays of 1 2 and 2 2 arrangement yield 3 dB AR bandwidths of 50.7% (1.36 GHz, 2-3.36 GHz) with respect to the CP center frequency, 2.68 GHz, and 56.4% (1.53 GHz, 1.95-3.48 GHz) at the CP center frequency, 2.715 GHz, respectively. This paper deals with the designs and experimental results of the proposed crossed dipole with parasitic loop resonators and its arrays.Index Terms-Broad axial ratio bandwidth, circularly polarized dipole, crossed dipole, dipole array.

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Bandwidth-Enhanced Low-Profile Antenna with Parasitic Patches

“…In order to redirect a half of the radiation into the opposite direction, the crossed-dipole antennas are generally horizontally placed on a metallic reflector [14]. In addition, the operational bandwidth of conventional crossed dipoles can be broadened by loading parasitic elements [15,16] or by using an enlarged dipole [17,18]. However, the crossed-dipole antennas equipped with a metallic reflector suffers from a large profile, which is approximately λ/4.…”

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“…In addition, the compact crossed dipole antenna is another effective method to enhance the AR bandwidth of CP antennas. In [8][9][10][11][12], CP characteristics are produced by crossing two dipoles through a 90 • phase delay line of a vacant-quarter printed ring. Although the appropriate 3-dB AR bandwidth of the antenna in [13] is achieved, its impedance bandwidth is narrow and the gain of the antenna is not satisfactory.…”