| Products - Marx Generator Driven IRA, 6' Dish | |||||||||||||||||||||||||||
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| MARX GENERATOR DRIVEN IMPULSE RADIATING ANTENNA, 6 FT DISH | |||||||||||||||||||||||||||
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APELC has developed an Impulse Radiating Antenna (IRA) that consists of a TEM-horn-fed parabolic reflector that is directly driven by a 22-J, 400-kV Marx generator. The maximum volumetric footprint is 10 ft x 6 ft x 7.75 ft. The system is two man portable and single man operational.
The Marx Generator The Marx generator specifications are listed in the table below. The generator is similar in construction to APELCs MG15-3C-940PF but has 5 stages removed to accommodate a peaking circuit that is confined within the Marx Generator housing.
RF Specifications An in-line balun is used to gradually transition from the coaxial Marx generator geometry to the parallel plate feed required for the TEM horn. An unbalanced TEM horn feeds the parabolic reflector. ¼” brass rods are used source to minimize aperture blockage. The parabolic reflector has a diameter of 180 cm and a focal distance of 68.2 cm (F/D = 0.38). The far field of the system begins beyond 5 m.
System Design
Simulations were performed with CST Microwave Studio using solid models generated from Solidworks. The RF transition was sourced by a unipolar impulse with a 600 ps rise time, a 15 ns fall time, and a total excitation interval of 40 ns to allow the simulated system to reach quiescence. Near Field Simulation Results Simulations were performed following the determination of the optimal source to reflector separation distance. The top down view reveals a spherically diverging wavefront which is approximately conformal to the spherically converging geometry of the parabolic reflector. The side on view in shows a somewhat broken spherical wavefront, likely caused by an asymmetrical unipolar excitation which results in behavior as a half TEM feed antenna. RF Measurements The entire system was tested following the low-voltage diagnostics and the cable load testing of the Marx generator. RF measurements were conducted on a 10-m antenna range using an A. H. Systems double ridge guide horn (model SAS-570) as the receiving antenna. The system was tested at a charge voltage of 40 kV and optimal peaking switch pressure. A peak radiated electric field amplitude of approximately 220 kV/m (when normalized to a distance of 1 meter) was achieved. Conclusions APELC has developed a Marx driven IRA capable of radiated electric field strengths in excess of 200 kV/m at a normalized range of 1 m and a center frequency of 210 MHz. |
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SYSTEM REQUIREMENTS
• Compressed dry air source (250 psig) • High voltage power supply (40 kV) • High voltage trigger generator (~15 kV)
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