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Old 27-Feb-2017, 12:10 AM   #12
rabbit73
Retired A/V Tech
 
Join Date: Aug 2012
Location: S.E. VA
Posts: 2,544
Quote:
Is it almost certain that something like the AD V4 will work better?
Nothing is certain with an attic and trees involved. You just have to try it. It does have more gain than a folded dipole, and about the same as a 3-element wire yagi, but it might not be enough for WBRA. Do you have room for an antenna that is about 10 feet wide with a 5 foot boom?
Quote:
ADTech, you mentioned the V4 is a cut to channel antenna, do you trim all three components?
You don't trim anything. The term "cut to" means that the V4 was designed to work on channels 2-6, but the best on CH4.
Quote:
What is the difference between the V4 and Winegard HD7000R?
The V4 is designed for VHF-Low, real channels 2-6, and has more gain on that band than the 7000R. The 7000R is designed for all three TV bands, and doesn't have a lot of gain on any of them.
Quote:
Is there an advantage to a full wavelength vs 1/2 wavelength antenna?
A fullwave dipole has little more gain than a halfwave dipole, but it is twice as long. For channel 3, it would be 16 feet long instead of 8 feet. We see fullwave dipoles in UHF bowtie antennas that have fullwave dipoles for each bay. A fullwave dipole is often called a collinear pair, because it has two halfwave dipoles in line side-by-side. The bowtie antenna is derived from the collinear array.







We also see fullwave elements in UHF and VHF loop antennas. Think of it as a folded dipole that has been opened up to form a circle, rectangle, or square. The folded dipole has two halfwave wires connected at the ends.

The most interesting fullwave loop antenna is the element used in Antennas Direct UHF antennas. Think of it as a fullwave dipole that has fat ends to increase the bandwidth, the way that whiskers increase the bandwidth in the bowtie antenna. Then, imagine that the ends are bent up to meet each other and join. This creates a tapered loop. Don't make one to sell, Antennas Direct holds the patent.



Instead of a 3 element ch 3 yagi, you could make a 3 element quad antenna, with 3 fullwave loops, 1/4 wave on each side, about 45 inches. The director loop would be a little smaller and the reflector loop a little larger.
Attached Images
File Type: jpg UHF Tapered Loop2.JPG (142.3 KB, 2187 views)
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Last edited by rabbit73; 27-Feb-2017 at 1:54 AM.
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