High-power VLF transmitter facility utilizing a balloon lofted antenna

Koons, H. C.; Dazey, M. H.

doi:10.1109/tap.1983.1143044

Cited by 12 publications

(3 citation statements)

References 10 publications

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“…Therefore, VLF antennas have large dimensions and are frequently constructed to take advantage of local geographical features, such as natural valleys, mountain ranges, and volcanic craters, for suspension of their radiating elements [Watt, 1967]. Vertical antennas of lengths exceeding 1 km have even been suspended from helium-filled balloons [Koons and Dazey, 1983]. At ELF the input impedance of vertical dipoles becomes intolerably large, and then it is more usual to resort to horizontal electric dipole antennas to excite the earthionosphere waveguide, in spite of their low efficiency [Burrows, 1978].…”

Section: Introductionmentioning

confidence: 99%

ELF and VLF radiation from the “polar electrojet antenna”

Barr¹,

Stubbe²

1984

Radio Science

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First, an approximate evaluation is made of the ELF/VLF dipole moment of the polar electrojet antenna established by ionospheric heating via the use of powerful HF waves amplitude modulated with frequencies in the ELF/VLF range. Then, the theory of reciprocity is used to determine the magnitude of the ELF/VLF waveguide excitation produced by such a dipole immersed in the ionosphere. Propagation under a series of ionospheres ranging from quiet auroral nightime to disturbed auroral daytime is considered. contrast between land and seawater, this method was found not to be feasible in practice [Wait, 1979; Bart, 1980]. More recently, Getmantsev et al. [1974] have shown that the D region of the ionosphere, when illuminated by a powerful source of HF radiation amplitude modulated at an extremely low frequency, can also act as a source of ELF radiation. The observed field strengths were quite small (• 10-1ttV m-•) and were explained in terms of nonlinear detection of the modulated HF signals in the ionosphere [Kotik and Trakhtengerts, 1975]. This work at midlatitudes has been continued by Ferraro et al. [1982] who, working with the powerful HF heating facility at Arecibo, have also generated ELF/VLF radiowaves in the D region of the ionosphere. Stubbe and Kopka [1977] suggested that by working at high latitudes, in the region of the polar electrojet, a much more effective VLF/ELF transmitting source could be produced in the ionosphere. Such a system has been in operation near Tromso in Norway for 3 years, and typical field strengths • 100 ttV m-x have been recorded 20 km south of the heating site when operating with an HF effective radiated power of 100 MW modulated at a few kilohertz [Stubbe et al., 1981[Stubbe et al., , 1982. ELF radiation from the electrojet, when heated byRussian low-frequency transmitters, has also been invoked as a mechanism to explain the reception of 1-kHz "pips" on ELF receivers in Northern Europe [Cannon, 1982]. Initial estimates of the radiation efficiency of the polar electrojet antenna (PEJ) have assumed the antenna to be in free space [Stubbe and Kopka, 1977; Cannon et al., 1982], but more recent calculations at ELF by Bart and Stubbe [1983] have shown that these simplistie analyses tend to overestimate the effective radiated power. This current work extends the ELF calculations of Barr and Stubbe into the VLF range and calculates the excitation of the five least 1111 FROM POLAR ELECTROJET 1113 BARR AND STUBBE: RADIATION FROM POLAR ELECTROJET Wait, J. R., On natural slot antennas, Radio Sci., 14(5), 765-766, ß 1979. R. Barr,

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Section: Introductionmentioning

confidence: 99%

ELF and VLF radiation from the “polar electrojet antenna”

Barr¹,

Stubbe²

1984

Radio Science

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“…rough the measurement of electric field intensity as a function of distance from balloon lofted antenna and radiated power by antenna as a function of frequency, the performance of the facility is worth relying [8]. With the help of the method of moments and the butterfly mating optimization, Li et al [9] have minimized electric field of top-wire insulator grading rings on the VLF transmitting antenna.…”

Section: Introductionmentioning

confidence: 99%

Structural Parameters Optimization of Corona Ring of Tethered Balloon-Type VLF Antenna

Wang

Zhang

et al. 2021

International Journal of Antennas and Propagation

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The antenna end of the tethered balloon-type high-power VLF communication system will be exposed to an extremely strong alternating electric field environment when it is in operation. Due to dielectric loss, an abnormal temperature rise may occur at the antenna end, which may lead to an antenna fracture in serious cases. It is an effective measure to install a corona ring at the end of the antenna to prevent such accidents. In this paper, the structural parameters of the corona ring, including ring radius, tube radius, and ring depth, are optimized based on intelligent optimization algorithm to significantly improve the electric field distribution and restrain the temperature rise to the maximum extent. The effectiveness of the optimization results is verified by simulation.

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“…Because the antenna would exceed one-quarter wavelength at very low frequency (VLF), it could radiate VLF with high efficiency and wide bandwidth at low driving voltages. We therefore incorporated VLF into the demonstration, making a hybrid ELF electrically short balloon-hoisted VLF transmitting antenna is described by Koons and Dazey [1983].…”

Section: Introductionmentioning

confidence: 99%

An aerostat‐supported ELF/VLF transmitter

Field¹,

Kies²,

Bannister³

et al. 1989

Radio Science

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A demonstration of an aerostat-supported extremely low frequency/very low frequency (ELF/VLF) transmitting antenna was performed. At ELF the vertical electric dipole (VED) antenna radiated at least 100,000 times more power than would a horizontal electric dipole having the same moment. That efficiency was achieved with an altitude of 12,500 feet (3810 m). Calculations show that the radiated power will increase as the fourth power of aerostat altitude. The tether antenna exhibited a corona onset voltage of 180 kV and was resistant to the degrading effects of ELF corona. Prolonged in-corona operation is therefore possible. The antenna was continuously tuned, despite changes in height and capacitance caused by the aerostat flight dynamics. The huge 300-H ELF tuning inductor posed no problem. Enhanced VED moments were achieved at ELF by operation at voltages up to 260 kV, 40% above the corona onset voltage. At VLF the antenna emulated a monopole that had a radiation efficiency greater than 90%. The measured bandwidths were large: 1.5 kHz at 23 kHz and 3.5 kHz at 34 kHz. The antenna height exceeded one-quarter wavelength at VLF, so the antenna could be tuned capacitively and required relatively low base voltages. At both VLF and ELF the measured fields agreed closely with predictions.

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High-power VLF transmitter facility utilizing a balloon lofted antenna

Cited by 12 publications

References 10 publications

ELF and VLF radiation from the “polar electrojet antenna”

ELF and VLF radiation from the “polar electrojet antenna”

Structural Parameters Optimization of Corona Ring of Tethered Balloon-Type VLF Antenna

An aerostat‐supported ELF/VLF transmitter

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