Originally Posted by pyedog
Thanks for providing this!
I have limited space in my attic for a 3rd UHF only antenna that I'm trying to use to pick up a single station. My goal is to mount it above my 4228 pointing in the opposite direction - thus It can't be very tall or long.
From looking at your chart I have a couple questions:
1) The DB8 is listed at 14.0 dBd while the CM 4228 is at 11.9 - I have a hard time beliving there is that much difference between two VERY similar antennas - do 4 separate reflectors really help?
2) The Blonder Tongue BTY-UHF-BB would seem to be the pick for a compact UHF antenna at 10.2 dBd and only 24" - but is it really this good? Obviously the price is beyond reason, but I can't imagine why other manufacturers wouldn't build a similar antenna if they can get this much gain from this small of a size - there are many far larger antennas with less gain.
Right now the 43XG would seem to be the best for the size (at 39" it is as large as I can fit) - but I'm a bit dubious about the numbers given the abnormally high DB8 numbers.
Any other suggestions for a compact UHF attic antenna?
Although the DB-8, CM4228 and WG PR8800 appear to be very similar 8-Bay antennas,
the feed structures and reflector screens are electrically quite different.
It is frequently difficult to determine whether a manufacturer is specifying "typical" or "minimum" specs,
i.e. whether it's an average/median value or a guaranteed for 90+ percent of shipped units.
Or perhaps was only measured on the carefully tweaked prototype model....
And sometimes it's difficult to determine whether they used dBd (relative to a dipole)
or the 2.15 dB "inflated" dBi (relative to isotropic) gain measurement units.
CM and Winegard provide very detailed spec sheets with gain, beamwidth and Front/Back Ratio for several UHF channels.
However, Antennas Direct simply claims "15.8 dB gain" for the DB-8, where it is unclear whether this is
in dBd or dBi (2.15 dB higher) units....and whether this is an AVERAGE across the UHF band or (much more likely),
the MAXIMUM gain for the BEST channel....
I determined the "14.0 dB" value for average UHF gain, by converting
15.8 dbi to 13.6 dBd and gave then the benefit of the doubt by simply rounding up to guessitimate the average UHF gain....
I would guess that this is actually MAX vice AVERAGE, so it's probably still overinflated by 2-3 dB...
I rechecked the "Data UHF NEC + Measured" spread sheet page which contains NEC Simulations results for average UHF gain.
The NEC Sim data points have been updated and provided via downloadable "ants.xls" file since I "eyeballed" data off the charts.
My "eyeballed" CH14 gain numbers were off by quite a bit (too small) with only minor tweaks for other channels.
Updated averages are below.
CM4228, 14.6 dBd measured, 11.3 dBd NEC Sim vs 11.9 dBd "spec"
PR8800, 13.2 dBd measured, 10.0 dBd NEC Sim vs 11.6 dBd "spec"
AD DB-8, unk dBd measured, 11.9 dBd NEC Sim vs 15.8 dB? "spec"
Surely, you can you see which "spec" claim doesn't fit....
Also, if you check www.hdtvprimer/ANTENNAS/comparing.html
you'll see that the author did not include the (presumably 1-2 dB) loss
in the DB-8's combiner in the NEC model.....
So all of the 8-Bay antennas are "close", with the edge given to the CM4228....
Kerry Cozad measured 1.4 dB MORE average gain across the UHF band for the CM4228 than the PR8800....
which is consistent with NEC Sim.
And actual on-the-air test results generally show that all three 8-Bay antennas are very good,
with the CM4228 having a reportedly small performance (and price) advantage....
BTW: Due to receiving both the direct path and the "ground bounce" signal, Kerry Cozad's model range test data can be
2-3 dB higher than "isotropic", i.e. "free space" gain cited in NEC simulation results and (presumably) also spec sheets.
Fortunately, Antennas Direct isn't the only source of data on the 43XG:http://cpc.farnell.com/jsp/endecaSea...sp?SKU=AP00815http://cpc.farnell.com/jsp/endecaSea...cpc/253268.xml
Probably dBi units (subtract 2.15 to find dBd).http://www.ceda-antenna.com/index.htmhttp://www.funke.nl/
Hmmm, CEDA website seems to be down and Funke is rebuilding theirs...
Guess I'll just attach the data sheet.....
Based on comparison to "simple" antennas, I've determined that Funke uses the inflated dBi units rather than dBd.
And, as is usual with non-U.S. antenna manufacturers, you have to be careful to read the frequencies (in MHz)
and might have to convert their channel numbers into U.S. channel numbers.
NL - Funke 43el Bowtie Reflector - 220_140302_dcf4543_230505_790501400.pdf 169.6572265625k . file