Circularly polarized broadband antenna using waveguide and an L-shaped feed probe

Reduction of cross polarization in higher frequency for circularly polarized broadband antenna with L-Shaped probe and parabolic short wall

“…Fig. 2 (d) shows a comparison of AR and gain characteristics (φ = 0 • , θ = 90 • ) between the proposed antenna and the previous antenna [5]. AR characteristics are slightly deteriorated in lower frequency range.…”

“…Fig. 3 shows comparisons of radiation pattern between the proposed antenna and the previous antenna [5]. Cross polarization level barely changes in the x-y plane.…”

“…In [4], inserting poles at the inside corners of the waveguide is effective to reduce the effect of higher order mode of TM 11 which deteriorates good broadband axial ratio (AR) characteristics. Besides, further wideband characteristics are achieved by optimizing the center frequency, inserting thin poles and shifting the feed point [5]. This antenna attains 10-dB S 11 bandwidth of 50.8% and 3-dB AR bandwidth of 54.4% in the boresight direction.…”

“…A broadband CP waveguide antenna using an L-shaped probe has been proposed in [2]. Since that, numerous broadband CP antennas using an Lshaped probe have been proposed [3,4,5]. In [4], inserting poles at the inside corners of the waveguide is effective to reduce the effect of higher order mode of TM 11 which deteriorates good broadband axial ratio (AR) characteristics.…”

“…Therefore, the parabolic short wall attains lower cross polarization level in higher frequency. For achieving lower AR, four fine square poles with a cross section of 2 × 2 mm are installed parallel to the x axis at the corners [5] as shown in Fig. 1.…”