Loop Antenna
 

Does anyone have an idea regarding the affect of
a T shaped loop? I know that a circle has larger
ap then a delta loop or square loop. Would an effect
be realized with a T?

Bill
N1EY

William H. O'Hara, III wrote:
Does anyone have an idea regarding the affect of
a T shaped loop? I know that a circle has larger
ap then a delta loop or square loop. Would an effect
be realized with a T?

Bill
N1EY

Start at an extreme case for the T. If the two conductors of the T's
stem are close together, then your T loop's stem is going to act like
open feedline. If the two conductors of the T's top are close together,
then your T loop's top is going to act a folded dipole.

Opening parellel sides of the stem or/and the top makes the structure
move towards becoming a square (rectangular) assembly.

If you keep the lower end of the stem close together and widen the top
of the stem, then the T moves towards an inverted delta assembly.

Duane
N6JPO

I would think such an antenna would be difficult to adjust to avoid
adverse
phase interactions...

================================

On the other hand there are an equal number of advantageous interactions.

"William H. O'Hara, III" wrote in message
. 97.142...
Does anyone have an idea regarding the affect of
a T shaped loop? I know that a circle has larger
ap then a delta loop or square loop. Would an effect
be realized with a T?


sounds like a folded dipole. - and it should act like one too.
you'll find that if you can move the 'vertical' part of the 'T' (feedpoint)
using a pully setup, that the arrangement can be used for several bands.
put a 4-1 balun at the bottom of the T.



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"Hal Rosser" wrote in
:


"William H. O'Hara, III" wrote in
message
. 97.142...
Does anyone have an idea regarding the affect of
a T shaped loop? I know that a circle has larger
ap then a delta loop or square loop. Would an effect
be realized with a T?


sounds like a folded dipole. - and it should act like one
too. you'll find that if you can move the 'vertical' part
of the 'T' (feedpoint) using a pully setup, that the
arrangement can be used for several bands. put a 4-1 balun
at the bottom of the T.

What happens if I do this,

300 feet
--------------------
| | 1
| | 0
| 100 ft 100 ft| 0
|_____ ______| ft
| |
| | 9
| | 0
| | f
|_______| t
FEED


Any thoughts?

Thanks
Bill N1EY

The free demo version of EZNEC available from http://eznec.com can
easily answer questions just like this.

Roy Lewallen, W7EL


William H. O'Hara, III wrote:

What happens if I do this,

300 feet
--------------------
| | 1
| | 0
| 100 ft 100 ft| 0
|_____ ______| ft
| |
| | 9
| | 0
| | f
|_______| t
FEED


Any thoughts?

Thanks
Bill N1EY

Roy Lewallen wrote in
:

The free demo version of EZNEC available from
http://eznec.com can easily answer questions just like
this.


It refuses to calculate SWR due to multiple wires
running so close would create interactions.

Bill

There shouldn't be any problem with that antenna. Please send me the
description (.EZ) file as an email attachment, and I'll look it over.

Roy Lewallen, W7EL

William H. O'Hara, III wrote:
Roy Lewallen wrote in
:


The free demo version of EZNEC available from
http://eznec.com can easily answer questions just like
this.



It refuses to calculate SWR due to multiple wires
running so close would create interactions.

Bill

On 12-Dec-2004, "William H. O'Hara, III" wrote:

Roy Lewallen wrote in
:

The free demo version of EZNEC available from
http://eznec.com can easily answer questions just like
this.


It refuses to calculate SWR due to multiple wires
running so close would create interactions.

Bill

Hi Bill,

Not sure about EZNEC Demo, but EZNEC 3.0 models it and gives Source Data (SWR) in the 600 to 1200
ohm range. Maybe you should check your connections and try again. For what it's worth, the pattern
is like most large horizontal loops, except for two large lobes in the direction of the top corners
of the tee.

Ken Fowler

I did quickly in the middle of the night. I will
look it over and see I can find some problem with
the wires. I used EZNEC demo 4.0.

Thanks
Bill

Maybe you should check your connections and try again. For
what it's worth, the pattern is like most large horizontal
loops, except for two large lobes in the direction of the
top corners of the tee.

Ken Fowler

"William H. O'Hara, III" wrote in
. 97.142:


I did quickly in the middle of the night. I will
look it over and see I can find some problem with
the wires. I used EZNEC demo 4.0.

Thanks
Bill

Maybe you should check your connections and try again. For
what it's worth, the pattern is like most large horizontal
loops, except for two large lobes in the direction of the
top corners of the tee.


I did get it to model SWR with high reactances(to me anyways).
Does this seem right? I dunno. Thanks

Bill

On Tue, 14 Dec 2004 18:46:22 -0600, "William H. O'Hara, III"
wrote:
I did get it to model SWR with high reactances(to me anyways).
Does this seem right? I dunno. Thanks

Hi Bill,

At this point, you need to provide more specifics. One, what
frequencies? Two, did they match your experience with a physical
model?

To answer your question lacking this information, yes this seems right
- at least somewhere in the panorama of all possible outcomes. It
stands to reason that ANY antenna, when looked at across a wide enough
spectrum, will reveal both resonances and high reactances, and many
combinations in between. This is just par for the course.

Now, if you find you are experiencing these high reactances in nature
as well as in modeling; then try one thing: Break the wire at a point
that is on the opposite side of the loop from the feedpoint and see
what happens.

73's
Richard Clark, KB7QHC

On 14-Dec-2004, "William H. O'Hara, III" wrote:

"William H. O'Hara, III" wrote in
. 97.142:


I did quickly in the middle of the night. I will
look it over and see I can find some problem with
the wires. I used EZNEC demo 4.0.

Thanks
Bill

Maybe you should check your connections and try again. For
what it's worth, the pattern is like most large horizontal
loops, except for two large lobes in the direction of the
top corners of the tee.


I did get it to model SWR with high reactances(to me anyways).
Does this seem right? I dunno. Thanks

Bill

The reactive components are just an indication that the applied frequency is too high (+X), or too
low (-X). Adjust the frequency or the size of the loop till X = 0. Or just don't worry about it
and use high impedance parallel line with a tuner.

Ken Fowler

Now, if you find you are experiencing these high reactances
in nature as well as in modeling; then try one thing:
Break the wire at a point that is on the opposite side of
the loop from the feedpoint and see what happens.

I haven't strung the actual one yet.
My EZNEC model got everything high. There wasn't
a frequency better than 8:1. Everything was much
higher. I am going to try with the square loop.

Bill

Bill

On Wed, 15 Dec 2004 19:04:36 -0600, "William H. O'Hara, III"
wrote:
My EZNEC model got everything high. There wasn't
a frequency better than 8:1. Everything was much
higher. I am going to try with the square loop.

Hi Bill,

Still need some particulars:
What frequencies?
What length of wire?
How high?

73's
Richard Clark, KB7QHC

Richard Clark wrote in
:

On Wed, 15 Dec 2004 19:04:36 -0600, "William H. O'Hara, III"
wrote:
My EZNEC model got everything high. There wasn't
a frequency better than 8:1. Everything was much
higher. I am going to try with the square loop.

Hi Bill,

Still need some particulars:
What frequencies?
What length of wire?
How high?

73's
Richard Clark, KB7QHC


12# wire at 40 feet in the air with 90 feet to each
side for the basic square. I wanted to see it would
resonate on 80 down.

bill

On Thu, 16 Dec 2004 18:23:46 -0600, "William H. O'Hara, III"
wrote:

12# wire at 40 feet in the air with 90 feet to each
side for the basic square. I wanted to see it would
resonate on 80 down.

Hi Bill,

Even at a glance and simplistic conversion to metric would say you
were expecting 120M of wire to resonate at 80M. Far too much wire.

73's
Richard Clark, KB7QHC

Richard Clark wrote in
:

12# wire at 40 feet in the air with 90 feet to each
side for the basic square. I wanted to see it would
resonate on 80 down.

Hi Bill,

Even at a glance and simplistic conversion to metric would
say you were expecting 120M of wire to resonate at 80M.
Far too much wire.


I should actually double it. Tree configuration
is very tough. I do the have the option of potentially
doing a T shape or the box with 90 feet sides.

Not up yet.. Getting side tracked

Bill

On Sat, 18 Dec 2004 20:01:25 -0600, "William H. O'Hara, III"
wrote:
Far too much wire.
I should actually double it.
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