Design of Compact Wide-band Folded Loop Feed Antenna for Parabolic Reflectors

A simple design of a dual linear polarized compact folded loop based feed antenna, operating from 1 to 15 GHz, is presented. The design of a new wide-band twin-lead line to microstrip line Balun required for broadband matching is also explained. The dimensions of the feed are 220 mm × 220 mm × 60 mm. The proposed feed antenna is developed in-house and characterized in an antenna measurement facility at an anechoic chamber. The measured gain of the feed antenna is 8.0 ± 2 dBi from 1 to 9 GHz and 6.0 ± 2 dBi from 10 to 15 GHz. 10 dB beam-width is ±55°, which is nearly constant from 1 to 15 GHz frequency range and makes it suitable for reflector illumination with high aperture efficiency. Port isolation of the feed is better than 20 dB and cross-polarization is better than 15 dB over the band. Simulated and measured gain, cross-polarization, and S-parameters of dual-polarized feed are presented and compared. Based on the secondary pattern analysis from the measured feed pattern, the developed feed is suitable for parabolic reflector antennas operating in the 1–15 GHz frequency range.