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Radiation from a finite sinusoidally modulated reactance surface (SMRS)


  • S. H. Cho,

  • R. J. King


An integral equation is used to study numerically the surface field and radiation from a finite planar structure which has a sinusoidally modulated reactance. The surface reactance is assumed to be uniform near a magnetic line source and modulated sinusoidally in the propagation direction beyond the uniform segment. On the modulated section of the surface, the magnetic field is essentially that for an infinitely long SMRS, provided that most of the energy is radiated through the fast waves before they reach the termination. By taking account of the radiation through the fast waves only, approximate expressions for the radiation pattern are also obtained. The approximated pattern compares well with the radiation pattern found numerically which includes all of the extraneous radiation due to the source, the transition between the uniform and the modulated reactance sections, and the termination insofar as the main beam and the largest sidelobe are concerned. The effects of the parameters such as the modulation amplitude, period, length of modulated section, and the average surface reactance are discussed.

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