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The Earth Station
Published in Jerry D. Gibson, The Communications Handbook, 2018
The antenna itself can vary in design, but it is usually a parabolic dish with a feedhorn assembly. The feedhorn is the point at which satellite signals are collected from the antenna reflector surface to be fed to receive equipment. It is also the point where transmit signals are sent out to the reflector surface of the antenna to be focused into a beam aimed toward the satellite. The diameter of the reflective surface determines the gain and beamwidth of the antenna. The gain of the antenna becomes an important part of calculating a system link budget to determine the quality and availability of the signal.
From launch to transmission: satellite communication theory and SNG
Published in Jonathan Higgins, Satellite Newsgathering, 2012
Note that if a linearly polarized feedhorn receives a circularly polarized signal, the signal can be received on both X and Y polarizations, though at −3 dB (half power) compared to a correctly adjusted circularly polarized feedhorn.
Earth Stations
Published in A.F. Inglis, A.C. Luther, Satellite Technology: An Introduction, 1997
The dual-reflector antenna [Figure 4.1(b)] is an important variation. The feed horn is aimed away from the main reflector; its beam is intercepted by a subreflector and reflected back to the main reflector.
Linear to Circular Polarization Converter Single Layer Reflectarray Antenna
Published in Electromagnetics, 2021
Reza Shamsaee Malfajani, Alireza Gholipour, Zahra Atlasbaf
CST Studio Suite is used for simulations and full-wave analysis of the designed reflectarray. The antenna is fabricated on an RO4003 substrate with a thickness of 0.813 mm. LP feed horn antenna and the measurement setup in which the feed is placed along the center of the reflectarray at the distance of 38 cm is shown in Figure 8. Radiation pattern measurements for the feed horn antenna (ETS 3160–08) show of 17 and 18 at E-plane and H-plane, respectively (the normalized radiation pattern is modeled by ).
A single layer SIW H-plane Horn Antenna with nearly equal E- and H-plane beamwidths
Published in Electromagnetics, 2020
Robab Kazemi, Rasoul Safamanzar
However, the main limitation of these antennas is their unequal E- and H-plane radiation patterns, as H-plane horn has narrow beam in H-plane and wide beam in E-plane. When an H-plane horn is used as a reflector feed, the asymmetric beam pattern results in a degraded aperture efficiency and large spillover power loss, as the feed does not perfectly illuminate the reflector. In order to improve the gain and efficiency of a prime focus reflector, the radiation pattern equalization of the feed horn is an essential requirement (Mak and Luk 2009; Olver et al. 1994; Potter 1963).
A novel twin conjugate matched feed for dual-beam offset reflector antennas
Published in Electromagnetics, 2021
Ranajit Dey, S B Chakrabarty, M B Mahajan
The design of the feed has been carried out for offset reflector having diameter D = 600 mm, F/D = 0.5, and offset angle θ0 = 90°. The twin conjugate matched feed has been simulated and designed in Ansys HFSS-18. The modal amplitude variations with frequency of TE21 mode for H- and V-polarization are shown in Figures 3 and Figures 4, respectively. The modal phase variations with frequency of TE21 mode relative to TE11 mode for H- and V-polarization are shown in Figures 5 and Figures 6, respectively. The simulated radiation pattern of the twin conjugate matched feed horn is shown in Figure 7. The schematic diagram of the offset reflector with twin matched feed is shown in Figure 8. The secondary simulation has been carried out using TICRA, GRASP-10.6. The secondary pattern has been simulated for the twin matched feeds using the feed horn without posts, i.e., shared aperture simple TE11 mode horn, and the corresponding feed horn pattern is shown in Figure 9. In Figure 9, the secondary pattern has been simulated exciting one of the shared aperture feeds. Here, the pattern is in the direction of beam peak. The secondary cross-pol. using the above-said feed horn is −16 dB over the specified bands. From the focal region field analysis, the calculated TE21 modal power w.r.t. TE11 mode at the aperture of the feed for maximum cross-polar field cancellation is −6 dB. The optimized values of the TE21 modal power w.r.t. TE11 mode of the designed twin feed is close to −6 dB ± 1 dB which are shown in Figures 3 and Figures 4. The secondary radiation patterns of the reflector with exciting H and V polarized feed of the twin matched feed horn are shown in Figures 10 and Figures 11, respectively. It has been observed that the cross-polarization component is −32 dB for the twin conjugate matched feed at Ku-band at the center frequency, which is an improvement of 16 dB. The cross-polar bandwidths of the twin matched feed are shown in Figure 12. Cross-polar bandwidth better than 5% for 10 dB improvement in cross-polarization is achieved.