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Input Admittance, Directivity and Quality Factor of Biconical Antenna of Arbitrary Cone Angle
  • Ramakrishna Janaswamy
Ramakrishna Janaswamy
Univerisyt of Massachusetts

Corresponding Author:[email protected]

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Abstract

New analytical expressions and numerical results for the quality factor and directivity as well as computationally convenient expressions for the input admittance of a symmetrical biconical antenna of arbitrary length $L$ and cone angle $\theta_0$ are presented. The quality factor for a wide-angle biconical antenna is shown to very closely approach the Chu’s limit of $Q = (kL)^{-1}\{1+(kL)^{-2}\}$. Numerical calculations based on the analytical formula for antenna admittance confirm the conjecture that Foster’s reactance theorem remains invalid even for perfectly conducting antennas. Furthermore, the variation of directivity of a wide-angle biconical antenna is a slowly varying function of its electrical length and is shown to depart significantly from that of a thin cylindrical dipole.
May 2022Published in IEEE Transactions on Antennas and Propagation volume 70 issue 5 on pages 3248-3258. 10.1109/TAP.2021.3138511