Optimum Current Distributions on Vertical Antennas

Paz, Lincoln La; Miller, G. A.

doi:10.1109/jrproc.1943.230327

Cited by 23 publications

(2 citation statements)

References 7 publications

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“…The far-field pattern function is now more clearly related to the 2D Fourier transform of the current density pattern Π θ over the unit sphere. The far-field expression (10) indicates that there are no dc components of the source excitation radiated into the far field and that the radial dependence is that of a spherical wave. The Fourier transform integral determines if there are any preferred directions into which the fields are radiated.…”

Section: Needle Radiation From Currents On a Small Spherementioning

confidence: 99%

“…Both end-fire (maximum radiated power is oriented along the array direction) [8] and broadside (maximum radiated power is oriented perpendicular to the plane of the array) [9] pattern enhancements from different array configurations were considered initially. La Paz and Miller [10] purported to show that the maximum directivity from an aperture of a given size was fixed, but Bouwkamp and De Bruijn [11] correctly demonstrated that there was no theoretical limit on the directivity from an aperture of any size. Dolph realized that one could control the sidelobe levels of the pattern by properly weighting (Chebyshev polynomial tapering) the amplitudes of the element excitations [12].…”

Section: Introductionmentioning

confidence: 99%

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Using Huygens Multipole Arrays to Realize Unidirectional Needle-Like Radiation

Ziolkowski

2017

Phys. Rev. X

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For nearly a century, the concept of needle radiation has captured the attention of the electromagnetics communities in both physics and engineering, with various types of contributions reoccurring every decade. With the near-term needs for highly directive, electrically small radiators and scatterers for a variety of communications and sensor applications, superdirectivity has again become a topic of interest. While it is well known that superdirective solutions exist and suffer ill-posedness issues in principle, a detailed needle solution has not been reported previously. We demonstrate explicitly, for the first time, how needle radiation can be obtained theoretically from currents driven on an arbitrary spherical surface, and we explain why such a result can only be attained in practice with electrically large spheres. On the other hand, we also demonstrate, more practically, how broadside radiating Huygens source multipoles can be combined into an end-fire array configuration to achieve needle-like radiation performance without suffering the traditional problems that have previously plagued superdirectivity.

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Section: Needle Radiation From Currents On a Small Spherementioning

confidence: 99%