Dear all,

Next year we will move to another house with a yard of about 1 acre.
After 35 years of dipoles finally a horizontal loop is within reach!

My most used band is 80 meters for local and mid-European communication.
A few times a year I participate in an HF-contest, but I am not a kind
of DX'er.

I want to feed the horizontal loop with about 200 feet of 600 Ohm open
line and use the loop for multiband 160 - 10 meters with a balanced
antennatuner.

The height of the loop will be about 35 feet and I will use wooden
supports for the loop.

It am planning to make a full-size loop for 80 meters. However, on this
yard it is easy to make a loop of 4 x 100 feet instead of 4 x 70 feet.

What is your opinion about the size 400 feet instead of a full-wave for
80 meters?

Thanks!


--

73,
Hans Remeeus (PA1HR)
http://www.remeeus.eu
Communication is about people, the rest is technology.

Hans,

I don't think it's worth it. The patterns and ground loss of the two
antennas at a height of only 35 feet are really very similar.

On the other hand, the impedance of the full wave loop according to
EZNEC is going to be around 100 ohms resistive, while the 100 foot per
side loop has an impedance of about 1500+j3200 ohms.

I'd recommend saving the extra 120 feet of wire for other antennas and
just building the fullwave.

Now, if you want to use the antenna with a tuner at the feedpoint or
perhaps open wire feed, the impedance of the 100 foot side loop on 160m
is much more reasonable (64-j1300) than the 70 foot per side loop
(EZNEC reports 8000-j30000! that is to say, infinite :-) )

73,
Dan

What is your opinion about the size 400 feet instead of a full-wave for
80 meters?





For anybody who can expound on the above question, I'd be interested in
the effectiveness of such loops that are a small increase in size over a
80M full-wave size too, such as approximately 300 - 350 feet. I, too, am
hoping for useful operation on 160, even though 80M is my primary interest.


Ed K7AAT

On Sat, 29 Jul 2006 18:53:53 +0200, Hans Remeeus
wrote:

What is your opinion about the size 400 feet instead of a full-wave for
80 meters?

Hi Hans,

An unnecessary change. Also, take care to anticipate that high
frequencies into a large antenna create many, many radiation lobes AND
nulls that may/may-not be useful.

73's
Richard Clark, KB7QHC

Now, if you want to use the antenna with a tuner at the feedpoint or
perhaps open wire feed, the impedance of the 100 foot side loop on 160m
is much more reasonable (64-j1300) than the 70 foot per side loop
(EZNEC reports 8000-j30000! that is to say, infinite :-) )



Dan,

I believe the original poster DID indicate he would feed the loop with
600ohm line and a balanced tuner.

Could you also run the Z figures for my plan of using a loop of 300
feet of wire on 160? ( 1.9000 MHz ) ... my height will be close to 50
feet, btw.

Tnx,

Ed K7AAT

K7AAT:

A loop of 87.5 feet per side (350 feet total) at 35 feet over average
earth shows a feedpoint impedance of 109-j2460 ohms in EZNEC... easier
to match than 8800-j30000 for sure.

73,
Dan

Ed,

517-j7600 for a 300 foot loop at 50 feet
still 110-j2500ish for the 350 foot loop at 50 feet.

This is a rapid fire thread!!

Good point on the multiband original post... didn't read carefully.
For 160 meters, the longer the better over an 80m fullwave. Richard
has a good point about multiband use but the extra length doesn't
change that caveat too much. If you've got an acre of land, it's
probably worth thinking about different antennas for the low bands and
the higher HF bands.

73,
Dan

wrote:
K7AAT:

A loop of 87.5 feet per side (350 feet total) at 35 feet over average
earth shows a feedpoint impedance of 109-j2460 ohms in EZNEC... easier
to match than 8800-j30000 for sure.

73,
Dan

Ed,

517-j7600 for a 300 foot loop at 50 feet
still 110-j2500ish for the 350 foot loop at 50 feet.



Thank you, Dan. I guess I ought to get myself EZNec sometime! It sounds
like what I can put up would "suffice" for 160M occasional operation... I
think the MFJ balanced tuner will handle that.


Ed

Yeah, Ed, I certainly don't mind doing a few quickie models here and
there, happy to do it.

It's worth ordering it, though, when you want to do something like I
did and model the pattern of your your five element 2m beam 16 inches
below your 6m moxon rectangle in the presence of your HF doublet and a
nearby aluminum roof, and generate the pattern for eight azimuth
directions.

It's a great tool to have if you like building antennas, especially if
you have complicated, site-specific improvements you might want to do.

Dan

Thanks to all for your nteresting information!

This evening I found another interesting site about large horizontal
loop antennas, including a very simple but effective tool. It can be
found on http://www.smeter.net/antennas/rjeloop4.php

I will make a horizontal loop of 4 x 25 meters (= 4 x 82 feet) for 160 -
30. And for the higher bands a 14 MHz full-size vertical delta loop.
Both with open feeder line.


--

73,
Hans Remeeus (PA1HR)
http://www.remeeus.eu
Communication is about people, the rest is technology.