The 40M band requires just over 4% bandwidth which is
equivalent to covering 28.0 to 29.2 on 10M. This CAN be
accomplished moderately well with full size elements
although it is definitely easier with dual driven elements.
Years ago, I had a 2L 40M Delta Loop suspended from
a 20 ft boom at 120 ft., tuned for CW. It was the only 40M
antenna I have ever had that would allow me to run EU on
40M SSB. Hunt and call was almost always "one call works all"
often without even using phonetics, just N 4 K G (over).
I don't recall the SWR in the phone band, but it was better
than any other 40M CW antenna I have had. Tuning for
7.1 MHz would probably suffice for a single DE.
I used 75 ohm CATV hardline, 3/4 inch dia., to run to the tower
and an RG59 jumper to the bottom center of the DE loop.
I 'assume' that I cut the feedline to be an odd number
of 1/4 WL's back to the transmitter.
Identical loops with 3/8 WL feedlines can be used to make
a reversible fixed 2L Loop antenna if BOTH sides of the
feedline are switched.
My CC 2L40 is also tuned for CW and works 'OK' on SSB
but is noticably less competitive on SSB than CW. I use
an MN2000 Antenna Tuner for SSB. K7LXC and others
recommend tuning between the CW and SSB dimensions.
de Tom N4KG
On Tue, 03 Jul 2001 Greg - N4CC <n4cc@fdn.com> writes:
> If you design a 40 meter quad, typically you design it for either the
> phone
> or cw band but what if you cut a driven element loop for say 7.025
> and
> another driven loop on the same set of spreaders cut for 7.25 -- and
> feed
> both of them simultaneously?
> Does anyone have any experience doing this or similar?
> Will bandwidth be improved? (I recognize that with a single
> wire loop for
> a reflector that gain will be compromised at some point...but I'm
> looking
> for a broadband solution with good SWR characteristics across the
> band and
> decent forward gain. I really don't care so much about f/b ratio.
> Some of you antenna or modeling experts must have some
> thoughts ???
> 73 de Greg-N4CC
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