Radiation quality factor, Q, of an electrically small lossless structure that fits an oblate spheroidal volume for transverse-to-axis polarisation is investigated. Q is evaluated for different size and shape of a spheroid by integrating numerically the stored energy associated with radiation. It is found that Q depends on the distribution of power amongst the various spheroidal modes, and a minimum of Q is achieved by suitable optimisation of the relative amplitudes of these modes. A graphical comparison between the minimum Q of a transversally polarised oblate and an axially polarised prolate spheroid is provided for ellipticities in the range 0.2,…,1. The inverse of the obtained minimum Q serves as an estimate for the bandwidth potential of an arbitrary, linearly polarised lossless radiator inside that volume.
|Journal||AEÜ: International Journal of Electronics and Communications|
|Publication status||Published - 2003|
|MoE publication type||A1 Journal article-refereed|