> 3 element stepir and the t8 will radiate almost the same
> signal strength at the other end.
Both modeling and theory strongly disagree with this ...
The active portion of an 8 element 13-32 MHz LP on an 180
foot boom is a small portion of the total boom length.
Here are model data of an 8 element LP (18 foot boom),
the SteppIR 3 element yagi (16 foot boom) and Force 12
C3E (extra 10 meter director and 18 foot boom).
The SteppIR/3 vs. 8 element LP vs. C3E (free space):
---------------------------------------------------------
LP SteppIR C3E
Band Gain F/R Gain F/R Gain F/R
20 5.0 9.2 7.4 25 6.6 10
17 4.9 12.3 8.3 25 3.0 2
15 4.8 13.0 8.5 20 6.2 11
12 5.0 14.9 8.8 15 4.4 5
10 5.1 14.5 9.0 11 7.4 23
6 n/a 10.1 20 n/a
The Log Periodic is a simplified model of an 8 element design
on an 18 foot boom. K9LA's work with the T-6 shows about .5
dB less gain for a shorter (12 foot boom) antenna while
Preliminary (unverified) results for a 10 element model (24
foot boom) show about .8 dB additional gain and 1-2 dB better
F/B (model data from AO).
The SteppIR/3 vs C3E numbers closely parallel the field test
data published by N0AX/K7LXC and SteppIR.
One can see that the LP fails to come even close to the SteppIR
- falling short my more than 3 dB except on 20 meters. Further,
falls one to two dB short of the typical gain of a two element
(Reflector/Driven with 50 Ohm feed).
An LP is a poor trade-off unless you have excess power and
need to operate on any frequency instead of the relatively
narrow amateur bands.
73,
... Joe, W4TV
> -----Original Message-----
> From: towertalk-bounces@contesting.com
> [mailto:towertalk-bounces@contesting.com] On Behalf Of anthony
> Sent: Saturday, January 23, 2010 9:45 AM
> To: towertalk@contesting.com
> Subject: [TowerTalk] lp V stepIR
>
>
> 3 element stepir and the t8 will radiate almost the same
> signal strength at the other end.More to fail with the stepir
> and did you see how much they cost??? WOW. big bucks. I would
> put up the t-8 and high grade coax like davis bury-flex. If
> done right this antenna will stay up without any maintenance
> for 20+ years. No way the step ir will do the same. Also you
> can buy two t-8's and one yaesu g-800s for what you would pay
> for a stepir. Just a thought.
>
> tony k2vi
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