I have been researching for a while now around the area of nested delta
loops. I want to upgrade my multi-band vertical antenna with delta loops,
each one resonant to cover 20 to 10m. However there is nothing on the
internet about nested delta loops. My wish is to have the delta loops
orientated such that they are pointed at the top and fed one third of the
way up one of the vertical sides to get a low angle of radiation.

I realise that they have an impedance of around 100 Ohms and this would need
to be matched. The usual method of doing this is to use a quarter wave
length of 75R coax to match to 50R.

Much in the same way that parallel dipoles can be fed with a common feeder,
can 5 delta loops be fed via coax matching stubs with a common 50R feeder?
(i.e. bring the ends of the matching stubs together?).

I tried in the summer to nest 5 delta loops with the feed point as described
above and then brought the feed points together (without matching stubs) ,
however it is not physically possible to do this - they really need
separating out.

Any ideas any one? My basic aim is to have 5 resonant antennas with no
tuning unit involved.

Thanks

John

Can it be done, - yes...
Will it work well - maybe!
You are going to have mutual coupling between the loops messing up
resonance and impedence... You cannot just cut the loops per the
formula and nest them inside of each other, connected at the feed
point, and still be resonant... That is your first problem... Search
the literature on triband quad loop beams and their results will point
the way to the appropriate modification of the usual loop formula...
Next, your impedences will drop and 100 ohms is not likely to be the
number...
For a single feedline try a quarter wave of twin lead from the mutual
feed point to each respective loop... Personally, I would use relays
to cut out the unused loops and save myself a lot of cut and try...
ymmv...
15 -17 will talk to each other... Try hanging them at right angles...

denny / k8do



John wrote:
I have been researching for a while now around the area of nested delta
loops. I want to upgrade my multi-band vertical antenna with delta loops,
each one resonant to cover 20 to 10m. However there is nothing on the
internet about nested delta loops. My wish is to have the delta loops
orientated such that they are pointed at the top and fed one third of the
way up one of the vertical sides to get a low angle of radiation.

I realise that they have an impedance of around 100 Ohms and this would need
to be matched. The usual method of doing this is to use a quarter wave
length of 75R coax to match to 50R.

Much in the same way that parallel dipoles can be fed with a common feeder,
can 5 delta loops be fed via coax matching stubs with a common 50R feeder?
(i.e. bring the ends of the matching stubs together?).

I tried in the summer to nest 5 delta loops with the feed point as described
above and then brought the feed points together (without matching stubs) ,
however it is not physically possible to do this - they really need
separating out.

Any ideas any one? My basic aim is to have 5 resonant antennas with no
tuning unit involved.

Thanks

John

On Fri, 29 Dec 2006 10:35:40 -0000, "John" wrote:

I tried in the summer to nest 5 delta loops with the feed point as described
above and then brought the feed points together (without matching stubs) ,

Hi John,

Without matching (stubs? these are usually shorted or open - perhaps
you mean lines) seems to go against your goal of a 5 band, no-tune
antenna. The alternative is to have 5 matching lines, a lot of wire
in the air.

however it is not physically possible to do this - they really need
separating out.

It would seem to be physically possible, just not elegant, nor
successful.

If you are willing to invest in such complexity and wire, why not ONE
antenna that does it all without such grief? Consult:
http://home.comcast.net/~kb7qhc/ante.../Cage/cage.htm
or
http://www.qsl.net/kb7qhc/antenna/Discone/discone.htm

73's
Richard Clark, KB7QHC

Much in the same way that parallel dipoles can be fed with a common feeder,
can 5 delta loops be fed via coax matching stubs with a common 50R feeder?
(i.e. bring the ends of the matching stubs together?).

Not necessarily no, but I think it will give you a headache. If you
don't have antenna modeling software on your side, you're going to have
to do it experimentally and you're probably not going to get much help
on the internet. You might consider going with full-wave rectangles
that are twice as high as they are wide. They don't need any matching
stubs; they're 50 ohms to start with.

There will be big interaction among any 5-HF-band loops at any rate.

You might do better with switching all five feedlines with a remote
coax switch of some description.

73,
Dan

Dear John in UK (no call sign):

Five bands (14, 18, 21, 24, 29 MHz?) with one transmission line shouts
for the use of a LDPA. You can construct one that will work using
information in the ARRL Antenna Book or several other references.

Prof. Cebik has a number of notes on this type of antenna
(www.cebik.com). A good place to start is:
http://www.cebik.com/lpda/lpd.html

A Michigan company that I understand has dealers in UK, is Tennadyne.
http://www.tennadyne.com/index.html
They make good quality, simple LPDAs. I have no connection to the firm.

Successfully nesting five tightly coupled antennas is a very difficult
task. A LPDA will work.

73 Mac N8TT

--
J. Mc Laughlin; Michigan U.S.A.
Home:

"John" wrote in message
...
I have been researching for a while now around the area of nested delta
loops. I want to upgrade my multi-band vertical antenna with delta loops,
each one resonant to cover 20 to 10m. However there is nothing on the
internet about nested delta loops. My wish is to have the delta loops
orientated such that they are pointed at the top and fed one third of the
way up one of the vertical sides to get a low angle of radiation.

I realise that they have an impedance of around 100 Ohms and this would
need
to be matched. The usual method of doing this is to use a quarter wave
length of 75R coax to match to 50R.

Much in the same way that parallel dipoles can be fed with a common
feeder,
can 5 delta loops be fed via coax matching stubs with a common 50R feeder?
(i.e. bring the ends of the matching stubs together?).

I tried in the summer to nest 5 delta loops with the feed point as
described
above and then brought the feed points together (without matching stubs) ,
however it is not physically possible to do this - they really need
separating out.

Any ideas any one? My basic aim is to have 5 resonant antennas with no
tuning unit involved.

Thanks

John

A full wave 20 meter delta loop, fed with open wire, ladder line or
even TV twin lead & a tuner will load up on all bands 10-40 meters.

Performance on 10-20 will be good, 30 & 40 a little less so.

Terry
W8EJO



John wrote:
I have been researching for a while now around the area of nested delta
loops. I want to upgrade my multi-band vertical antenna with delta loops,
each one resonant to cover 20 to 10m. However there is nothing on the
internet about nested delta loops. My wish is to have the delta loops
orientated such that they are pointed at the top and fed one third of the
way up one of the vertical sides to get a low angle of radiation.

I realise that they have an impedance of around 100 Ohms and this would need
to be matched. The usual method of doing this is to use a quarter wave
length of 75R coax to match to 50R.

Much in the same way that parallel dipoles can be fed with a common feeder,
can 5 delta loops be fed via coax matching stubs with a common 50R feeder?
(i.e. bring the ends of the matching stubs together?).

I tried in the summer to nest 5 delta loops with the feed point as described
above and then brought the feed points together (without matching stubs) ,
however it is not physically possible to do this - they really need
separating out.

Any ideas any one? My basic aim is to have 5 resonant antennas with no
tuning unit involved.

Thanks

John

A full wave 20 meter delta loop, fed with open wire, ladder line or
even TV twin lead & a tuner will load up on all bands 10-40 meters.

Performance on 10-20 will be good, 30 & 40 a little less so.

Terry
W8EJO



John wrote:
I have been researching for a while now around the area of nested delta
loops. I want to upgrade my multi-band vertical antenna with delta loops,
each one resonant to cover 20 to 10m. However there is nothing on the
internet about nested delta loops. My wish is to have the delta loops
orientated such that they are pointed at the top and fed one third of the
way up one of the vertical sides to get a low angle of radiation.

I realise that they have an impedance of around 100 Ohms and this would need
to be matched. The usual method of doing this is to use a quarter wave
length of 75R coax to match to 50R.

Much in the same way that parallel dipoles can be fed with a common feeder,
can 5 delta loops be fed via coax matching stubs with a common 50R feeder?
(i.e. bring the ends of the matching stubs together?).

I tried in the summer to nest 5 delta loops with the feed point as described
above and then brought the feed points together (without matching stubs) ,
however it is not physically possible to do this - they really need
separating out.

Any ideas any one? My basic aim is to have 5 resonant antennas with no
tuning unit involved.

Thanks

John

A full wave 20 meter delta loop, fed with open wire, ladder line or
even TV twin lead & a tuner will load up on all bands 10-40 meters.

Performance on 10-20 will be good, 30 & 40 a little less so.

Terry
W8EJO



John wrote:
I have been researching for a while now around the area of nested delta
loops. I want to upgrade my multi-band vertical antenna with delta loops,
each one resonant to cover 20 to 10m. However there is nothing on the
internet about nested delta loops. My wish is to have the delta loops
orientated such that they are pointed at the top and fed one third of the
way up one of the vertical sides to get a low angle of radiation.

I realise that they have an impedance of around 100 Ohms and this would need
to be matched. The usual method of doing this is to use a quarter wave
length of 75R coax to match to 50R.

Much in the same way that parallel dipoles can be fed with a common feeder,
can 5 delta loops be fed via coax matching stubs with a common 50R feeder?
(i.e. bring the ends of the matching stubs together?).

I tried in the summer to nest 5 delta loops with the feed point as described
above and then brought the feed points together (without matching stubs) ,
however it is not physically possible to do this - they really need
separating out.

Any ideas any one? My basic aim is to have 5 resonant antennas with no
tuning unit involved.

Thanks

John

NomadW8 wrote:
A full wave 20 meter delta loop, fed with open wire, ladder line or
even TV twin lead & a tuner will load up on all bands 10-40 meters.
Performance on 10-20 will be good, 30 & 40 a little less so.

EZNEC says the feedpoint of a 20m loop will be about
3000-j13000 on 40m. The SWR on the ladder-line line
will be around 130:1. For better performance on 40m,
install an insulator opposite the feedpoint thus
turning it into a dipole of sorts on 40m. Short across
the insulator for 20m operation.
--
73, Cecil http://www.w5dxp.com

Or a 1/4 wave 40 meter stub (aka wave trap/auto switch).



Cecil Moore wrote:1. For better performance, on 40m,
install an insulator opposite the feedpoint thus
turning it into a dipole of sorts on 40m. Short across
the insulator for 20m operation.
--
73, Cecil http://www.w5dxp.com