Abstract
Abstract. Interesting, "new", very high peak-power pulsed radio frequency (RF) antennas have been assembled at the HIPAS Observatory (Alaska, USA) and also at the University of California at Los Angeles (UCLA, USA); namely, a pair of quarter wavelength (λ/4) long cylindrical conductors separated by a high voltage spark gap. Such a combination can radiate multi-megawatt RF pulses whenever the spark gap fires. The antenna at HIPAS is 53m long (λ/2) with a central pressurized SF6 spark gap. It is mounted 5 meters (λ/21) above a ground plane. It radiates at 2.85MHz. The two antenna halves are charged to ± high voltages by a Tesla coil. Spark gap voltages of 0.4 MV (at the instant of spark gap closure) give peak RF currents of ~1200A which correspond to ~14 MW peak total radiated power, or ~56 MW of Effective Radiated Power (ERP). The RF pulse train is initially square, decaying exponentially in time with Qs of ~50. Two similar but smaller 80-MHz antennas were assembled at UCLA to demonstrate their synchronization with a pulsed laser which fired the spark gaps in the two antennas simultanoeously. These experiments show that one can anticipate a pulsed array of laser synchronized antennas having a coherent Effective Radiated Power (ERP)>10GW. One can even reconsider a pulse array radiating at 1.43MHz which corresponds to the electron gyrofrequency in the Earth's magnetic field at ~200km altitude. These "new" pulsed high power antennas are hauntingly similar to the ones used originally by Hertz (1857-1894) during his (1886-1889) seminal verifications of Maxwell's (1864) theory of electrodynamics.
Highlights
Electromagnetic, or E and M, waves at ∼50 MHz were first generated in the year of 1886 when a pair of 30-cm diameter conducting spheres (∼15 pF each) were interconnected by two one-meter long straight conductors (∼1.5 μ H inductors), through a central spark gap (Bryant, 1988)
When the spark gap fired, the system radiated powerfully enough to induce a faint spark in another gap in a distant resonant receiving loop (Bryant, 1998)
A twenty cycle L–C line, consisting of 60 50-kV–8 nF ($250 each) capacitors, was designed. This approach was abandoned in favor of the simpler “frozen voltage” generator used originally by Hertz; namely, a pair of oppositely charged high voltage quarter wave long antennas separated by a spark gap
Summary
Electromagnetic, or E and M, waves at ∼50 MHz were first generated in the year of 1886 when a pair of 30-cm diameter conducting spheres (∼15 pF each) were interconnected. A twenty cycle L–C line, consisting of 60 50-kV–8 nF ($250 each) capacitors, was designed This approach was abandoned in favor of the simpler “frozen voltage” generator used originally by Hertz; namely, a pair of oppositely charged high voltage quarter wave long antennas separated by a spark gap. These experiments show that energy storage antennas can be made to emit coherently when triggered by a powerful enough laser pulse. When the 80-MHz antenna was operated with an open-air spark gap its Q was even worse, ∼2 These experiments clearly showed that a coherent array of laser triggered pulsed Hertzian radiators could be assembled that can match or exceed the peak power of the new HAARP system for a fraction of its cost
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