Comments on "Pattern characteristics of harmonic and intermodulation products in broad-band active transmit arrays"

[Comments and authors' reply] Active array antenna patterns at harmonic and intermodulation (IM) frequencies have been studied (for original paper see ibid., vol. 50, p. 858-865 (2002)). In particular, the beam directions have been found at IM and harmonic frequencies for different scenarios. Multiple beams may also exist at IM and harmonic frequencies. [Author's reply] Pointing out that a multiple signal transmit array with grating lobes will have intermodulation (IM) lobes associated with the grating lobes, as well as with the main lobe, is an important point. In some array applications, this can be very significant. Also, an array with significant energy radiated at a harmonic could support "harmonic grating lobes" even if the fundamental pattern does not have grating lobes.