On 2/25/2011 9:28 AM, Joe Subich, W4TV wrote:
>> Yeah, but there's another variable besides forward gain, bandwidth
>> and feedpoint impedance: front-to-back ratio. The 3-el and 4-el
>> SteppIRs have only about 11 dB F/B on 10m, which is less than half
>> the F/B of a 3-el or 4-el 10m monobander with optimized element
>> spacing.
> You are correct, the 11 dB F/B on 10 meters is because the reflector
> to driven element spacing has begun to approach 1/4 wave. That's one
> reason for the optional fixed parasitic elements on six meters.
>
> I'm not convinced that high F/B is particularly important.
It depends on where you live the band opening, and the frequency. Even
here in Michigan with a good band opening on 20 I find F/B important. It
often makes the difference between being able to copy and not. On 40
meters (not part of a tri-bander) F/B is essential. To those living in
the central US or central Europe it could become much more important
during sunspot cycle highs.
73
Roger (K8RI)
<snip>
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