----- Original Message ----- From: Jeff DePolo To: [email protected] Sent: Thursday, July 02, 2009 7:39 AM Subject: RE: [Repeater-Builder] DB-224 patterns on side of tower.
...that's gain realized due to compression of the elevation pattern. We're talking about azimuthal gain - the horizontal radiation pattern. --- Jeff WN3A . Right! And they're not mutally exclusive, as evidenced in stacked yagis. You don't lose the gain achieved through compressing the elevation pattern when you add gain in one cardinal direction at the expense of another. If we start with a vertical colinear dipole array, with an otherwise omnidirectional gain pattern of 6 dBd, and overlay a 3 dB azimuth offset induced by interaction with a support leg which behaves roughly like a yagi's reflector, we should still expect the average horizon field strength of any two bearings 180º apart, whether they're north/south, east/west, 41º/221º, etc., to still be about 6 dBd, not zero. If the dipoles in the colinear array were stacked 2-element yagis, just a driven element and a reflector, the same thing would happen (only with much sharper backside nulls due to the properly-sized reflector). - Paul, AE4KR
