Abstract:
In the hf range radiation from aircraft must be accomplished by exciting radiating currents on the airframe itself. One method of exciting such currents is by shunts or n...Show MoreMetadata
Abstract:
In the hf range radiation from aircraft must be accomplished by exciting radiating currents on the airframe itself. One method of exciting such currents is by shunts or notches which electrically penetrate the airframe. The strength of coupling of such devices is analyzed and shown to be proportional to the square of the normal mode current which they interrupt. A theory is developed and substantiated by experimental data, which enables the prediction of the impedance characteristics of such antennas. It is shown that these antennas are most effective when located in a region of high current concentration, and that the current concentration which occurs in the fillet area of swept-wing aircraft makes this area particularly favorable for their installation. Shunt and notch antennas, when they can be used, have a number of structural advantages over cap-type antennas, and certain electrical advantages also. They require no special lightning protection and eliminate the need for special isolating devices. In general, they are capable of handling higher powers before encountering high-altitude voltage breakdown.
Published in: IRE Transactions on Antennas and Propagation ( Volume: 6, Issue: 1, January 1958)
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1.
J. V. N. Granger, Wing-Cap and Tail-Cap Aircraft Antennas, March 1950.
2.
J. V. N. Granger, "Shunt-excited flat-plate antennas with applications to aircraft structures", Proc. IRE, vol. 28, pp. 280-287, March 1950.
3.
J. V. N. Granger and J. T. Bolljahn, "Aircraft antennas", Proc. IRE, vol. 43, pp. 533-550, May 1955.
4.
W. L. Jones, Notch Coupling to the Electromagnetic Resonances of a Delta Wing Aircraft, December 1955.
5.
E. J. Moore, Performance Specification and Evaluation of Liaison Antennas, November 1953.
6.
These admittance data were obtained by actual measurement on a full scale mock-up of a light aircraft with a wing span of 36 feet. The measurements were made with the aircraft mounted on an insulating tower 40 feet high. An appropriate scaling factor is used.
7.
This example is cited through the courtesy of the Douglas AirCraft Co., Tulsa Division. G. A. OReilly of Douglas supervised the model measurements.
8.
The simple theory as stated here neglects the radiation resistance due to the loop or transmission line mode. This component is the major contributor to the actual impedance at the frequency which makes the shunt λ/2 in length.
