Comments on "Anomalous mutual coupling between microstrip antennas" [with reply]

The paper by Haddad and Pozar (see ibid., vol.42, no.11, p.1545, 1994) contains important observations about the mutual coupling between printed antennas. It presented the oscillatory behavior of the mutual coupling between two printed dipoles as the separation between elements is increased. The authors used a closed form asymptotic Green's function to evaluate the mutual impedance between the elements. The oscillatory behavior of the mutual coupling is supposed to be a consequence of the interference between the surface waves and the space waves. The authors of the aforementioned paper stated that this behavior was previously unreported. Rosales here comments that the "anomalous" oscillatory behavior of the mutual coupling between microstrip antennas was in fact reported in a paper presented at the Ninth Computing Conference on the Computation of Electromagnetic Fields, and by Haddad and Pozar in their paper, almost simultaneously. The results and conclusions of both papers confirm each other. Haddad and Pozar reply to the Comment.