loop antenna questions

[Jim]

i am constructing the typical bcb receiving loop. its 18 inches on a
side, 15 to 18 turns, 365 variable cap, the usual setup. my question is
this, is it feasible to throw one or two turns on the same frame
parallel to the other turns to tune a sw loop? does the proximity of the
other bcb loop wreck the characteristics of the sw loop? how about if i
switch the variable from one loop to the other, leaving the opposite
loop open and untuned? or how about switching in taps, decreasing the
number of turns at each interval to tune from bcb up to sw? would the
unused turns on the frame make the remaining loop untuneable?

[Telamon]

In article <17382-42...@storefull-3138.bay.webtv.net>,
inagadd...@webtv.net (Jim) wrote:

If I understand you what you want to do is make two loops, one for MW
and the other for SW with fewer turns for two resonate loops.

You could just leave the terminals open on the unused loop where it
would not affect the in use loop much.

--
Telamon
Ventura, California

[RHF]

JIM,
.
SIDE-BY-SIDE PAIR OF LOOP ANTENNAS AM/MW & SHORTWAVE :
You might try Making the Width (Spreader Arms) Wider and have an
Inch or Two separation between the two Loops. Try Three to Five
Turns as a Starting Point for the Shortwave Loop Antenna.
.
CONCENTRIC PAIR (Big-&-Small) LOOP ANTENNAS AM/MW & SHORTWAVE :
Instead of a Pair of Side-by-Side Loops. Consider having your
'smaller' Shortwave Loop Antenna inside the Larger AM/MW Broadcast
Band Loop Antenna. If your AM/MW Loop is 18" on a Side then try
making the Shortwave Loop between 13" to 15" on a Side and try
Three to Five Turns as a Starting-Point.
.
BY-THE-NUMBERS : Loop Antenna Calculators
http://www.ourhousenews.com/loopAnt.php4
http://www.mindspring.com/~loop_antenna/amloop_calc4.htm
.
.
THE BETTER SHORTWAVE LOOP ANTENNA IDEA :
The better idea may be to make a separate Shortwave Loop Antenna
using Coax Cable. A Single Turn Shielded Loop Antenna can work
very well as an In-Door Low Noise Shortwave Antenna where an
Out-Side Antenna is not allowed or where there is a high local
RFI / EMF Noise Environment.
NOTE - Use your MW Loop Antenna by itself for the AM/BCB Band.
.
The "GreerTech" Coax Cable [Shielded] Loop
Antenna is good and very practical.
LOOP=> http://www.greertech.com/hfloop/mymagloop.html
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1625
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1730
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1539
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1008
.
RG8 AND RG58 'type' COAX CABLE "IN-DOOR" LOOP ANTENNAS
http://tinyurl.com/7ygcf
<http://groups-beta.google.com/group/rec.radio.shortwave/msg/a76e2b951e35abd9>

These "Shielded" Loop Antenna made out of RG8 Coax Cable.
- Low Noise Receive ONLY Coax Loop Antennas for 160-10 Meter Bands
http://www.greertech.com/hfloop/mymagloop.html
http://www.iri.tudelft.nl/~geurink/images/coupling_loop_schematic.jpg
- An Easy-to-Build general purpose RECEIVE-ONLY small Wire Loop
http://www.greertech.com/gpmag/gpmagloop.html
.
Also there is the PLUMBER's Lopp Antenna {Broad-Band}
http://www.csd.uwo.ca/~nic/radio/radio.shtml
.
There is also the SLINKY on a "Hula Hoop" Loop Antenna which is
Low-Cost and Easy-to-Make and can used for the Shortwave (HF) Band.
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/858
.
Check-Out the "Loop Antennas" eGroup on YAHOO!
LOOPS => http://groups.yahoo.com/group/loopantennas/
.
More about Loop Antennas => http://tinyurl.com/4k9sm
<http://groups-beta.google.com/group/rec.radio.shortwave/msg/a634348788936b04>

And More => http://tinyurl.com/6frv4
<http://groups-beta.google.com/group/rec.radio.shortwave/msg/53b54c66c0bb3f38>

.
.
iane ~ RHF
.
All are WELCOME and "Invited to Join" the
Shortwave Listener (SWL) Antenna eGroup on YAHOO !
<http://groups.yahoo.com/group/Shortwave-SWL-Antenna/>
.
Some Say: On A Clear Day You Can See Forever.
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/502
.
I BELIEVE: On A Clear Night . . .
You Can Hear Forever and Beyond, The BEYOND !
With a Shortwave Listener SWL Antenna of your own making.
"If You Build It {SWL Antenna} You Will Hear Them !"
.
.

[Jim]

i like the idea of the smaller loop inside the larger one. the frame is
for an edge winding like a box loop. i could do a spiral winding for the
sw loop inside, then the nulls would be at 90 degree angles to help
avoid interaction. my purpose is to have both sw and bcb available on
the same antenna lead because my radio uses the same ant input jack for
both sw and bcb antennas. i want one portable package that eliminates
the need to change plugs to go from sw to bcb. i can mount a switch to
drop the variable across the winding i need and save wear and tear on my
plugs. thanks for your thoughts!

[RHF]

JIM,

One more thing to consider the difference in the "Spacing"
of the Turns for the Two 'separated' Loops :
.
* AM/MW Loop Antenna can have 'many' Turns and the "Spacing"
of these Wires can be Close Together [Side-by-Side] or with
a Small "Gap" of 1/16" to 3/16" between the turns.
.
* Shortwave Loop Antenna will have a just a few Turns and
can have a greater "Spacing" {Gap} of 3/8" to 3/4" between
the Turns.
.
REF => Loop Antenna Questions :
Paired ? -or- A Pair ? -or- Totally Separate ?
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/2421

.
iane ~ RHF
.

.