This paper proposes a dual-band circularly polarized antenna with ``X'' parasitic structures applied in the Beidou satellite navigation system. The innovation of this paper is to introduce the radome with ``X'' parasitic structures to broaden the beam width of the L-band and to improve the low-elevation gain of the antenna. Furthermore, high dielectric constant materials are used to realize the miniaturization and embedded application of the antenna. The measured results show that the VSWR of the L-band is 1.09 at 1616 MHz, and the VSWR bandwidth (VSWR<2) is 45 MHz (1589 MHz-1634 MHz). The VSWR of S-band antenna is 1.24 at 2492 MHz, and the VSWR bandwidth (VSWR<2) is 54 MHz (2471 MHz-2525 MHz). By adding the designed radome, the 20-degree elevation gain of the L-band is increased by 3.755 dBic. The measured results show that the gain variation at 20-degree elevations of the antenna at 1616 MHz and 2492 MHz are 4.981 dBic and 3.7 dBic, respectively. Moreover, the beam widths of the antenna at 1616 MHz and 2492 MHz are 130 degrees and 104 degrees, respectively. The antenna has an improved gain and a good roundness at low elevation angles, thus providing a favorable choice for navigation antenna solutions.
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