Doug Turnbull wrote:
> Gentlemen,
> I wonder what the attraction of the LP is when one can use a SteppIR.
> Am I wrong to believe that the Fwd gain and FB are better for a Yagi of the
> same number of elements tuned to the frequency of interest than an LP? Is
> it not the case that LP antennas have a lot of metal and hence wind loading
> for what they achieve? Wind loading is as important to me as gain and
> directivity. It is a big balancing act. Granted the SteppIR has a good
> bit of electronics but in my experience they seem to be reliable. Perhaps
> the SteppIR is more expensive for the same performance but Aluminum is
> pretty dear.
>
You've pretty much summarized the differences..It's a systems
engineering question and depends on your ultimate desires.
The SteppIR is more complex, but has less wind resistance, and
potentially better gain and F/B, and can switch 180 degrees very
quickly, but takes some short time to change frequency.
The LPDA is simpler (no moving parts), lower gain and f/b,
instantaneously changes frequency, has more wind drag area and is
heavier (I'm not sure about the latter).
If you're running comms for an embassy, running kilowatts on RTTY, the
dual LPDA is the ticket, especially if you're running an HF hopper or ALE.
If you're a ham, wanting to eke out the last tenth of a dB, the SteppIR
might be a better fit.
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