Quad Ridge Flared Horns
Frequency Range: FL to 6FL GHz
Aperture Efficiency for Half-Angle: HA >50%, typically >55%
(Aperture efficiency is for a fixed position of the feed relative to the reflector focal point; i.e., any degradation due to phase center variation with frequency is included in the specification.)
Output Reference Impedance: 50 ohms
Return Loss: >10 dB, >15 dB over 90% of the band
Maximum Diameter: 40cm / FL for HA=50
Length: 34cm / FL for HA=50
Approximate Weight: 0.7kg /( FL^3)
QRFH-HA-6-FL feeds are Quad-Ridge Flared Horn antennas designed to efficiently illuminate microwave reflector antennas over a frequency range of FL to 6FL GHz where FL is to be specified for each feed and can range from 0.5 to 3 GHz. The feeds are dual-linear polarized designed for a given half-angle, HA, subtended by the reflector or sub-reflector facing the feed, specified for each feed. A typical feed that has been constructed and tested with a shaped Cassegrain reflector is the QRFH-50-6-2 shown at left.
The feeds are constructed entirely of aluminum, except for the coaxial line center conductor and SMA connectors, which are gold-plated steel. The feed may be operated at any temperature in the 4K to 350K range with very little change in performance.
An important characteristic of all antennas is the scaling of performance with wavelength relative to dimensions. Thus the measured return loss and patterns of the antenna with FL=2 GHz can be expected at frequency 2/X GHz for an antenna with all dimensions multiplied by X. The QRFH antenna can be scaled except for the SMA connector which has only minor effect on return loss for frequencies up to 18 GHz.