The Phillips laboratory has recently designed and constructed a CW, low-level simulator (ELLIPTICUS) for use in determining coupling of electromagnetic energy to aerospace systems. The antenna is loaded with ferrite beads which have resistors wrapped around them so that a relatively constant resistive load is achieved over a large frequency band. Furthermore, the number of ferrites on the antenna is determined to make the field patterns similar to those produced at the high level pulse simulator, HPD.The HPD simulator with the HAG /I pulser was used to measure responses of the Same test points on the EMPTAC aiorcrai? which were measured with the CW simulator. This re or! examines how well the responses in the low level C W and high Lvel pulse simulators compare when normalized to similar incident field strengths.The Phillips Laboratory has recently desi ned a high frequenc low electric field amplitude, CW simulator, ELLIPTIC& [1,2]. A diagram oyihe ELLIPTICUS antenna is shown in Figure 1. The simualtor is constructed of two solid jacketed coaxial cables which are joined at the top of the antenna with a balun. The inside conducting surfaces of one of the coaxial cables acts as a feed to the balun, and currents from the output of the balun are delivered to the outside of the outer conductors of the coaxial cables. These currents are responsible for the fields created by the simulator.
Figure 1. The ELLIPTICUS SimulatorThis simulator was intentionally crafted to make the field atterns for this antenna much like those of the HPD simulator. Because the ligh level pulse simulator, HPD, has a resistive loading to control the low frequency ratio of the Electric-to-Ma netic field amplitudes, a method to achieve this criteria for the ELLIPTIC& antenna was also needed. In order to accomplish this, ferrite beads made of material number 77 were used. Figure 2 shows the real and imaginary loading presented by one of these beads to a current passing through it.. As can be seen in the figure, the impedance of a single bead is both resistive and reactive. 30 25 20 15 5 0 -5 -1 0 In
The high power microwave program at the Air Force Research Lab (AFRL) includes high power source development in narrow band and wideband technologies. The 112 source is an existing wideband source that was developed at the AFRL. A recent AFRL requirement for a wideband impulse generator to use in materials tests has provided the need to update the H2 source for the current test requirements. The H2 source is composed ofa dual resonant transformer that charges a short length ofcoaxial transmission line. The transmission line is then discharged into an output coaxial transmission line with a self-break Hydrogen switch. The dual resonant transformer is driven by a low inductance primary capacitor bank operating through a self-break gas switch. The upgrade ofthe coaxial Hydrogen output switch is the focus ofthis paper.The Hydrogen output switch was developed through extensive electrical and mechanical simulations. The switch insulator is made ofUltem 2300 and is designed to operate with a mechanical factor ofsafety equal to 4.0 at 1,000 psi. The design criteria, design data and operational data will be presented.
The JOLT system is a highly directive, impulse-like radiator. The antenna for JOLT is a IO-ft-diameter half-impulse radiating antenna (HIRA). JOLT was one of the first impul se radiating systems to employ a half IRA . For that reason , extensive measurements were made with a prototype, scale model HIRA in order to under stand the performance of this class of antenna. In addition, a serie s of low-voltage antenna subsystem tests were performed with the full JOLT antenna before it was couple to the pulsed power and run at high voltage. The low-voltage measurem ent s proved to be quite valuable , as an important manufacturing defect-a failure to mount the dish perpendicular to the ground plane-was identified and mitigated.
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