Use of log-periodic feeds in corner reflectors

Comparison of V-Grid Reflectors Fed with a Single Dipole or with Yagi Antennas

“…The frequency response for the V-grid reflector fed with a single dipole is almost flat for the range of frequencies considered, so it has a better bandwidth than the same reflector fed with a Yagi, at the expense of less gain and larger sidelobes. A similar result of limited bandwidth was found by (Stephenson & Finley, 1972) using a log-periodic feed, as well as very large VSWR values. However, this last reference does not mention anything about gain or FBR.…”

“…In Figure 1, the Yagi feed is shown with its directors positioned away from the reflector vertex, but it was also investigated what happened if the Yagi orientation was inverted. This last alternative demanded a larger separation S between the vertex and the folded dipole in order to allow enough room for the directors, and was considered to find out if, by any chance, the antenna could work in a "parabolic reflector fashion," providing increased gain and bandwidth performance with respect to that of an isolated Yagi, following a similar philosophy as Stephenson and Finley (1972) with the orientation of a log-periodic antenna feed.…”

“…This last arrangement gives an average gain of about 13 dBi. Likewise, some authors have reported results for corner reflectors that use a log-periodic feed trying to get increased bandwidth (Stephenson & Finley, 1972), but without significant success. On the other hand, although V-grid reflector antennas illuminated by Yagi exciters fed with folded dipoles are widely used in a variety of applications, no detailed information is available on their theoretical parameters of operation, so it is important to fill this gap and to know better their performance over a wide range of frequency, as compared with reflectors that use only a single dipole as feed.…”