Hi-VHF 4-Element Yagi Antennas - based on Dave47's antenna, designed per K7MEM (DL6WU) on-line calculator: http://www.avsforum.com/avs-vb/showthread.php?p=13785312 http://www.avsforum.com/avs-vb/showthread.php?p=16552404
Compares 300-ohm Folded Dipole Yagi (Dave47's) to 75-ohm non-folded Yagi: essentially the same performance. Same Boom Lengths=58.7-in.
Net Gain only covers Ch8 and Ch9. Raw Gain extends throughout Ch10, but with excessive SWR. So these 4-Element Yagis have LESS bandwidth than similar 8-Element Yagis.
NEC simulation normally does NOT include the boom. When constructing a real antenna, a "Boom Correction" is added to the length of each element to compensate for the additional loading from the metal in the boom, but ONLY when using METAL boom construction.
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Date(s): 30May2009. Album by holl_ands. 1 - 9 of 9 Total. 2017 Visits.
enlarge 0KB, 1024x747 1 Although Raw Gain covers Ch7-10, Net Gain is best only over Ch8-9. Rapidly falling Net Gain across Ch10 can cause reception problems.
Essentially no difference between 300-ohm Folded Dipole Yagi and 75-ohm "Normal" Yagi.