A. Vertical Array theory A.2. WAVE FRONTS AND SOURCE CURVATURE
than a continuous flat source.
If we compare the polar diagram of a continuous flat source to an array of curved sources, we see
that the dispersion is very similar, with small differences only in the lateral lobes. Imposing the condition
that the lateral lobes remain at a level of at least 10dB lower than the central lobe, we find that the
curvature of the source is one-fourth the wavelength of the lowest frequency it must reproduce.
Therefore it is not necessary, even in the use of a perfectly straight array, to use HF devices that are
perfectly flat.
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