Of course, SteppIR also has a loading coil that gives you coverage
across all of 80m and 60m with the BigIR vertical. The efficiency might
suffer a little (maybe 1-3 dB) compared to the higher bands since the
radiator is only about 1/8 wl on 80m, but it's probably a good
compromise, especially if you don't skimp on the radials.
Both the dipole and Super Loop (from Radioworks?) will have a variety of
lobes on the higher bands which can be hit or miss for specific paths.
The vertical has the advantage of a nice low angle omni pattern
(assuming no major nearby obstacles such as stucco houses or dense
trees). The gain of a vertical will probably be a bit lower than the
peaks of the lobes from the dipole or loop on the higher bands, but then
it will be higher compared to their many nulls. On the low bands
(80-40) a vertical with a good ground system can probably outperform the
dipole and loop for DX if they are under 3/8 wavelength above ground and
help keep the clouds warm.
I wouldn't put much faith in the mystical noise rejection property of
loop antennas on receive. There may be situation where they are (when
there is nearby lightning), but those are times I would unplug my
antennas and ground everything! For an explanation, check out:
http://www.w8ji.com/k9ay_flag_pennant_ewe.htm
Also, don't put much faith in Radioworks gain claims. Their ads were
written by salesmen, after all.
73, Terry N6RY
On 2009-09-21 4:43 AM, DAVID CUTHBERT wrote:
> The 130 foot dipole puts great demands on the 4:1 balun. Even if the balun
> does a good job of the 4:1 transformation the coax will still see a VSWR
> above 10:1 on every band. The loop, if one wavelength or more at 3.5 MHz
> will provide a lower VSWR and not tax the balun as much.
>
> The IR vertical will restrict you to 7 MHz and above. If this is acceptable
> it is a good choice with a modest or better GND system. By modest I mean a
> dozen 25' radials.
>
> Dave WX7G
>
>
> On Sun, Sep 20, 2009 at 3:32 PM, Robert Kirkland <alpha76@triton.net> wrote:
>
>
>> Which one would you prefer?. A 130 foot dipole center fed with 450 Ohm Twin
>> Lead into a 4 to 1 Balun and 52 Ohm Co-Ax to a Tuner. Or, a Super Loop into
>> a 4 to 1 Balun with 52 Ohm Co-Ax to (hopefully no) antenna tuner. Or a Big
>> IR vertical.
>> Bob, w5pvr
>>
>>
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