On 2015-02-28 12:18 PM, Wilson wrote:
I can’t imagine spending all that money to put that complicated
antenna up in the air when an LPDA will do the same thing with no
moving parts and, at most, 2dB of claimed gain.
A log-periodic is a poor third choice to a SteppIR or a multi-monoband
yagi. The LPDA has minimal gain and F/B - it typically uses less than
30% of the boom length and unless it has a large number of elements
for the boom length suffers from wide SWR excursions.
Oh, by the way a dipole above ground has 8.1 dB of "gain" (8.1 dBi).
The Log-periodic - particularly the "sparse element" designs typically
marketed to amateurs - will be lucky to show 2 dBd (10 dBi) when
installed above earth compared to 13 - 15 dBi for a three element
SteppIR, or 11 - 12 dBi for a multi-monoband yagi on a 12' boom. For
a Log-Periodic to even come close to matching the 3 element SteppIR
(16' boom) or multi-monoband yagi (12' boom) it will need to have
around 16 to 18 elements on a 30+ foot long boom. The LP will weigh
four times what the multi-monoband yagi and have four to five times
the wind load of the three element SteppIR - just to cover 13.5-30 MHz
even though both the SteppIR and multi-monoband antennas can include
6 meters with no significant increase in wind load or weight.
73,
... Joe, W4TV
On 2015-02-28 12:18 PM, Wilson wrote:
OK folks, now a word from our grinch:
I can’t imagine spending all that money to put that complicated
antenna up in the air when an LPDA will do the same thing with no
moving parts and, at most, 2dB of claimed gain. And at HALF the
price, with far lower maintenance liability. To each his (her) own,
but I’d rather not have all that technology up in the lightning
zone! It’s just no fun and the extra money will buy a LOT of beer!
Yes, I could afford one, but my second hand TH-3 is making me quite
happy. One of these days I’ll put up a log, when the WARC bands lure
me... 73, Wilson W4BOH
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