M.M. Gantsevich, A.V. Kharkov

High power microwave feeds illuminate reflected antennas or phased arrays, which are used in different types of microwave radars. Airtight waveguide feeder with high level microwave power is filled with pressed air. Some technical solutions of pot feed horns are considered. Four-channel circularly polarized feed horn was used in reflected phased arrays. It has two-tier sealing. Eight-channel waveguide feeder with cross-section of 120×57 mm was filled by air under pressure over 5 standard atm. and was separated from feed horns with quartz windows. The feed was placed in hermetical case, which was filled with slightly pressed by 50% mixture of non-ionized gas and air. The case was closed from the direction of horns with outer аirtight window. This window had several millimeters thickness and was made from composite material "polast" (interleave layers of polyethylene and glass cloth) Such feed radiated the microwave power up to 120 MWt in impulse at 144 KWt of average power. Four-channel feed horn of microwave power up to 20 MWt in impulse at 200 KWt of average power was developed for passed phased arrays. Power comes up to feed with water-cooled 72×34 mm waveguides. Multistep sealing with progressive pressure from 9 atm. in waveguides to 1 atm. in antenna was applied in this feed. Such construction simplifies requests to mechanical strength of sealing. The feed placed in case, which was filled by air pressed to 5 atm. Two same quartz plates set up at about half wavelength seal apertures of four feed horns. The cavity between quartz plates is blown by air under pressure of 2 atm. for electrical strength and cooling. External case is filled with 50% mixture of non-ionized gas and air pressed at 0,3 atm. It is closed with microwave transparent composite "polakvart", which was created with the use of quartz cloth. The circularly polarized feed of radio telescope reflector radiates continuous microwave power up to 300 KWt. Power comes to feed with the help of 35×15 mm waveguide. Open end of circular waveguide with diameter of 56 mm is used as feed. The feed is filled with 50% mixture of non-ionized gas and air pressed at 0,5 atm. The feed was sealed three-layered film consists from two outer polyethylene layers with lavsan or propylene in between which are reinforced by net. That seal has the form of a disk, with diameter of 100 mm. Average meaning of power flux density at the center of seal disk is about 7 Wt/cm3. Air-cooling sealed disk is used for prevention of thermal breakdown.