At 6/7/2008 17:18, you wrote: >"No, parallel-fed antennas do NOT suffer uptilt/downtilt as frequency is >varied unless the harness was special-ordered for factory downtilt. If the >antenna wasn't ordered with downtilt, all of the elements are fed in >phase, and they will always be in phase regardless of frequency." > >Jeff, the pattern depends on both phasing and spacing. As frequency drops, >the interelement phasing, expressed in degrees, remains the same, but the >spacing, expressed in degrees or wavelengths, drops. If you model a >colinear array of parallel-fed dipoles in an antenna software program, and >don't scale the dimensions as you scale the frequency, you'll see the main >lobe shift up or down, and "butterfly" lobes appear, as you get a few per >cent off-frequency.
I don't see the main lobe shift up or down with frequency in the NEC simulations; it stays on the horizon. It does get narrower at higher frequencies & wider at lower frequencies. The "butterfly" side lobes appear mainly at higher frequencies. Bob NO6B
