A Miniaturized Wide-Beamwidth Circularly Polarized Planar Antenna via Two Pairs of Folded Dipoles in a Square Contour

Abstract

A circularly polarized (CP) antenna with a wide axial-ratio (AR) beamwidth is presented by placing the two pairs of folded dipoles in a square contour. First, our study demonstrates that the CP radiation can be achieved at the broadside by setting a 90 • phase difference between the vertical-and horizontal-paired folded dipole radiators. Second, a radiation pattern subtraction approach is presented to explain how the radiation beamwidth of the paired folded dipoles could be appropriately widened or narrowed according to the radiation pattern subtraction of two opposite electric current densities in the folded dipoles. Using this approach, the E-plane beamwidth of a pair of folded dipoles is made certainly widened, whereas its H-plane counterpart becomes narrowed. On this basis, the Eand H-plane radiation patterns can still be made approximately identical with each other over a wide range of polar angle, even though the distance between dipoles is deliberately shortened. As such, the desired CP antenna with shortened dipole-to-dipole distance and unaffected wide AR beamwidth can be achieved using two pairs of parallel folded dipoles with shortened distance between them instead of linear dipoles in [24]. Finally, a CP printed antenna is designed and fabricated on a single dielectric substrate. Experimental results are found in good agreement with the simulated ones in terms of radiation patterns, gain, AR, efficiency, and reflection coefficient. In particular, the 3-dB AR beamwidth at the central frequency of 1.6 GHz is extended to 135 • at XZ-plane and 142 • at Y Zplane. Moreover, the overall size of the constituted CP antenna with folded dipoles is decreased to 0.43 λ0 × 0.43 λ0 (λ0 is the wavelength in free space).Index Terms-Circularly polarized antenna, folded dipole and radiation pattern subtraction, wide beamwidth. Y. Luo and Q.-X. Chu are with the

A Novel Circularly Polarised Antenna With Wide Power and Axial-Ratio Beamwidth by Using Tilted Dipoles

“…7 demonstrates the measured and simulated radiation efficiencies of the proposed antenna, which keep above 90% in the operating band. A comparison of the CP radiation performance is made between the proposed antenna and the previous designs in [5] and [9], as shown in Table 3. The data show that wider 3 dB ARBW and HPBW can be realized by the tilted dipoles.…”

Localization of Compact Circularly Polarized RFID Tag Using ToA Technique

“…Compared to linear polarization, circularly polarized tag antennas are theoretically proven to increase the read range of the tag by 41% [2]. Several circularly polarized tag antennas have been proposed based on planar dipole antennas [3], circular microstrip patch antennas [4], square patch antennas [2], and loop antennas [5]. However, these designs are large in size and incorporate multi-layered substrates that have a high dielectric value resulting in a bulky antenna.…”

Broadband, Wide Beam Circularly Polarized Antenna With a Novel Matching Structure for Satellite Communications

“…Moreover, wide beamwidth is also required to ensure the signal quality at any place on the earth [2]. CP antennas are divided in two types in general.…”

“…CP antennas are divided in two types in general. 1) single-fed antenna [3][4][5] and 2) dual-fed antenna [2,[6][7][8]. There is no external feed network for a single-fed antenna.…”

“…The antenna is a crossed-dipole fed by a broadband 90 • power divider. The axial-ratio bandwidth of the proposed antenna is larger than that of the antennas in [2][3][4][5][6][7][8]. The 3-dB beamwidth is larger than 88 • over the whole working frequency band.…”