1998 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.

IEEE Transactions on Antennas and Propagation
Volume 46 Number 2, February 1998

Biconical Antennas with Unequal Cone Angles

Page 181.

Abstract:

The problem of radiation and reception of electromagnetic waves associated with a spherically capped biconical antenna having unequal cone angles \psi _1 and \psi _2 is investigated. Both cones that comprise a bicone are excited symmetrically at the apices by a voltage source so that the only higher order modes are TM. A variational expression for the terminal admittance is derived. Under the wide-angle approximation, expressions for the radiated field, the effective height, and the terminal admittance are obtained. In addition, limiting values of these quantities are derived for electrically small and electrically large wide-angle bicones. The results for arbitrary cone angles are new and subsume results that appear in the existing literature as special cases such as where \psi _1 = \psi _2 or \psi _2 = \pi / 2. Moreover, the approximations of this paper are more accurate than many in the literature. It is argued that the radiation pattern of an electrically small cone is proportional to \sin\theta, which is similar to that of a short dipole; whereas the pattern behaves like 1 / \sin \theta for electrically large cones. The parameter \theta is the angle from the bicone's axis of symmetry to the observation direction. Consequently, the direction of maximum radiation changes with exciting frequency for a bicone of fixed length. Although most of the analyses are presented in the frequency-domain, time-domain responses of bicones are discussed for some special cases that are similar to situations considered by Harrison and Williams. In particular, the time-domain radiated field and the received voltage are shown to depend on the input's passband and on the match between the source and the bicone.

References

1. S. A. Schelkunoff, Electromagnetic Waves.New York: Van Nostrand, 1943, ch. XI.
2. P. D. P. Smith, "The conical dipole of wide-angle," J. Appl. Phys., vol. 19, pp. 11-23, 1948.
3. C. T. Tai, "On the theory of biconical antennas," J. Appl. Phys., vol. 19, pp. 1155-1160, 1948.
4. --, "A study of the E.M.F. method," J. Appl. Phys., vol. 20, pp. 717-723, 1949.
5. --, "Application of variational principle to biconical antennas," J. Appl. Phys., vol. 20, pp. 1076-1084, 1949.
6. C. H. Papas and R. W. P. King, "Input impedance of wide-angle conical antennas fed by a coaxial line," Proc. IRE, vol. 37, pp. 1269-1271, 1949.
7. --, "Radiation from wide-angle conical antennas fed by a coaxial line," Proc. IRE, vol. 39, pp. 49-51, 1951.
8. S. S. Sandler and R. W. P. King, "Compact conical antennas for wide-band coverage," IEEE Trans. Antennas Propagat., vol. 42, pp. 436-439, Mar. 1994.
9. C. W. Harrison and C. S. Williams, "Transients in wide-angle conical antennas," IEEE Trans. Antennas Propagat., vol. AP-13, pp. 230-246, Mar. 1965.
10. F. W. J. Olver, "Bessel functions of integer order," in Handbook of Mathematical Functions with Formulas, Graphs, and Mathematical Tables, M. Abramowitz and I. A. Stegun, Eds.New York: Dover, 1965, p. 360.
11. C. W. Harrison Jr., "Tables of impedance and radian effective length of wide-angle conical antennas," Sandia Nat. Labs., Albuquerque, NM, Rep. SC-R-662, June 1963.
12. A. Erdelyi, Higher Transcendental Functions.New York: McGraw-Hill, 1953, vol. 2, p. 183 [Eq. (53)] (Bateman manuscript project).
13. J. G. Siambis and R. E. Symons, "Ultrawide-band clustered-cavity^ TM klystron," in Ultra-Wideband, Short-Pulse Electromagnetics, H. L. Bertoni, L. Carin, and L. B. Felsen, Eds.New York: Plenum, 1993, p. 121.