Any one have any detailed plans on 40 Meter Half Square antenna? I
calculated 33.33 feet on verticals and 68.33 on horizontal. I was thinking
of feeding it at the corner, I think it will be close to 50 ohms. Now
center should go to the vertical and shield to horizontal....Another
question is the far end vertical is it connected or seperated from the
horizontal connection?

--
Scott Gordon
1-877-967-5734
Cell 614-419-3077
AOL- scott1gordon
Yahoo - ffsi_Scott
MSN - scottgordon
http://your.ffsi.com/60653
http://www.srgproperty.com

Scott Gordon wrote:
Any one have any detailed plans on 40 Meter Half Square antenna? I
calculated 33.33 feet on verticals and 68.33 on horizontal. I was thinking
of feeding it at the corner, I think it will be close to 50 ohms. Now
center should go to the vertical and shield to horizontal....Another
question is the far end vertical is it connected or seperated from the
horizontal connection?

It's not an exact science and you will have to trim for resonance
on your favorite frequency. Those are OK starting measurements.
The far end vertical wire is connected to the horizontal wire and
is usually just a continuation of the same wire with a 90 degree
bend. This is basically a phased array of two 1/4WL vertical
sections separated by 1/2WL and fed at a top corner or fed at
a bottom high impedance point through a base matching network.
--
73, Cecil http://www.qsl.net/w5dxp


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Scott Gordon wrote:
Any one have any detailed plans on 40 Meter Half Square antenna? I
calculated 33.33 feet on verticals and 68.33 on horizontal.

Near enough for a start - trim for resonance, as Cecil says.

I was thinking
of feeding it at the corner, I think it will be close to 50 ohms.

That's where it must be fed. Anywhere else, and it won't act as a
half-square (except the other top corner of course).

Now
center should go to the vertical and shield to horizontal....

That shouldn't matter at all.... but you really need a choke balun to
make *sure* of that. Coil up the first few feet of your feedline to make
a common-mode choke at the feedpoint (eg 10ft of RG-58 feedline, wound
into a flat coil of 6 turns). Then run the rest of the feedline away
from either leg of the antenna for as far as possible.

If you use that choke, then it won't matter which way around you connect
the centre and the shield. If you don't, then your antenna will consist
of the half-square *plus* the outer of your coax... which was probably
not what you intended.

Another
question is the far end vertical is it connected or seperated from the
horizontal connection?

Connected.


--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

Scott, I have been using a 30 meter HS for some time now, and according to
my dimensions and EZNEC, I get 65'6" for the horizontal wire and 37'7" for
the vertical 'tails'. However, what you are figuring may be close enough.
The horizontal wire length wire will cause the 'tails' to be longer or
shorter depending on what you make it. I've discovered that a SHORTER
horizontal wire (not by too much) and longer tails seems to give a tad more
gain, but not enough to notice. I did it so I could squeeze it in between 2
trees 46 feet apart (30 meters for mine, remember). Also, the coax can be
connected to either the coax center conductor to the short vertical section
or the longer section, it really doesn't matter. The longer section is one
long, continuous section of wire, roughly 3 1/4 wavelengths long with the
last 1/4 bent back towards ground to make the other vertical. The 1/2 wave
section of horizontal wire is a phasing line for what an HS is: top load
phased verticals. Corner load is what I do but find a way to keep the coax
away from the vertical wire. Mine comes off at an angle to another nearby
tree. It's easy to get interaction between the coax and the antenna and you
need to avoid that. Also, I'd suggest a coax choke at the feedpoint. I get a
1.1:1 match at 10.1.


"Scott Gordon" wrote in message
...
Any one have any detailed plans on 40 Meter Half Square antenna? I
calculated 33.33 feet on verticals and 68.33 on horizontal. I was
thinking of feeding it at the corner, I think it will be close to 50 ohms.
Now center should go to the vertical and shield to horizontal....Another
question is the far end vertical is it connected or seperated from the
horizontal connection?

--
Scott Gordon
1-877-967-5734
Cell 614-419-3077
AOL- scott1gordon
Yahoo - ffsi_Scott
MSN - scottgordon
http://your.ffsi.com/60653
http://www.srgproperty.com

"Ian White GM3SEK" wrote in message
...

Original poster said:

I was thinking
of feeding it at the corner, I think it will be close to 50 ohms.

Ian said:

That's where it must be fed. Anywhere else, and it won't act as a
half-square (except the other top corner of course).

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

eh?

Fed at the bottom via a parallel tuned circuit works, no ? You can see my
article in Ham Radio Magazine from many years ago on how to feed it that
way, (which is really the classical feed for this antenna...the corner fed,
with all of it's inherent problems came along a lot later, AFAIK)

Simply use a parallal tuned circuit at the base of either vertical, and tap
up from the bottom (ground side) of the coil for 50 ohms. The tuning cap for
the coil can be a piece of coax (at "x" pf per foot). I ran this antenna for
years, and I had the mistaken notion that it was a "half-square". Wonders
never cease...I would have thought the editor of the mag, a seemingly
knowledgable fellow, would have caught my mistake.

very big grin, tongue in cheek

73,

hasan, N0AN

hasan schiers wrote:

"Ian White GM3SEK" wrote in message
...

Original poster said:

I was thinking
of feeding it at the corner, I think it will be close to 50 ohms.

Ian said:

That's where it must be fed. Anywhere else, and it won't act as a
half-square (except the other top corner of course).

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

eh?

Fed at the bottom via a parallel tuned circuit works, no ? You can see my
article in Ham Radio Magazine from many years ago on how to feed it that
way, (which is really the classical feed for this antenna...the corner fed,
with all of it's inherent problems came along a lot later, AFAIK)

Simply use a parallal tuned circuit at the base of either vertical, and tap
up from the bottom (ground side) of the coil for 50 ohms. The tuning cap for
the coil can be a piece of coax (at "x" pf per foot).

Sorry, Hasan, you're absolutely right of course. I remember your Ham
Radio article very well.

What I should have said was "if you intend to use coax feed..."

It's also true that coax feed is not as easy as it looks, because of the
"hot feedline" problem. In many ways a small ground-mounted ATU is
better. Since the half-square is a monoband antenna, the ATU is "set and
forget" and it's very easy to get going as you say.

Well, not quite monoband... with different ATU settings, a 40m
half-square will also work as an end-fed half-wave "inverted U" for
short skip on 80m.


I ran this antenna for
years, and I had the mistaken notion that it was a "half-square". Wonders
never cease...I would have thought the editor of the mag, a seemingly
knowledgable fellow, would have caught my mistake.

very big grin, tongue in cheek

Even editors can have a bad day... looks like yesterday was one of them
:-)


--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

Hi Ian,

I thought you meant something like that, but I couldn't figure out how to
say it, and thought it would be "cute" to make a little joke at your
comments. Then I thought of "if you want to feed it with coax" way to state
what you were saying, but that wouldn't work either, because the tapped coil
is coax fed too. The real issue is how "easy" it is to direct feed with coax
by using the corner feed...but it has a host of common mode issues that
aren't that much easier to deal with than making the coil/cap combo in the
first place. The only thing that maks the corner feed "easy" is doing it
wrong and ignoring the common mode problems with routing of the feedline.

While I did write the article for HR mag, I must admit my only contribution
to the "art" was the clever use of a piece of coax for a high voltage,
easily tuned capacitor. If I hadn't hit on that solution, I would never have
even tried the half-square, as the weather protection and availability of kw
handling caps is a real issue.

I would encourage anyone wanting to do the half-square (a marvelous antenna)
to consider a piece of coil stock and a few inches of coax for the feed
point, in place of the corner feed. (Of course, this requires a VSWR bridge
or Antenna Analyzer to adjust the tap on the coil, but it certainly isn't
rocket science.) I used the 40m half-square for many years and it performed
flawlessly and required zero maintenance in a harsh Iowa climate of wind,
snow and ice.

The method I used for building it couldn't have been simpler. What I did was
get out a long piece of stranded wire, slid two egg insulators on 33 feet,
twisted the first insulator once or twice to anchor the insulator, slid the
2nd insulator 66 feet from the first, twisted it once or twice to anchor the
2nd insulator (now we have both corners), and then measured another 33 feet,
and cut the wire.

The nice part about this is, no soldering at the corners, one continuous
piece of wire and away ya go. I then pounded a ground rod in under the first
corner, mounted the air dux coil/coax cap bottom directly to the rod and the
bottom of the first vertical wire to the top of a plexiglas plate that held
the coil. Just about as simple as one could get. All the strain is on the
plexiglass.

I waterproofed the coax with a blob of clear silicon rubber....caution
here....the antenna will stop working until the blob "cures", as it shorts
out the open end of the coax (I chased this problem for a few hours until I
realized that until cured, the silicon rubber is a short circuit.

This configuration lasted many years and required no attention. I did end up
putting a plastic box over the coil to keep the snow/ice off the coil, but
that's all it took. I've often thought of putting another one up here at the
new qth, but I don't have trees in the right place like I did at the other
qth.

Anywho, my comments were all in good fun. Your observations evoked a lot of
pleasant memories from years ago about an antenna that was instructive and
fun to build, not to mention a sterling performer on 40m.

p.s., yes I did run it on 80m as well, and I was surprised how well it
worked, but then again, it becomes and end fed half-wave "bent" antenna. Two
for the price of one, "sort of".

73,

....hasan, N0AN

"Ian White GM3SEK" wrote in message
...
hasan schiers wrote:

"Ian White GM3SEK" wrote in message
...

Original poster said:

I was thinking
of feeding it at the corner, I think it will be close to 50 ohms.

Ian said:

That's where it must be fed. Anywhere else, and it won't act as a
half-square (except the other top corner of course).

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

eh?

Fed at the bottom via a parallel tuned circuit works, no ? You can see my
article in Ham Radio Magazine from many years ago on how to feed it that
way, (which is really the classical feed for this antenna...the corner
fed,
with all of it's inherent problems came along a lot later, AFAIK)

Simply use a parallal tuned circuit at the base of either vertical, and
tap
up from the bottom (ground side) of the coil for 50 ohms. The tuning cap
for
the coil can be a piece of coax (at "x" pf per foot).

Sorry, Hasan, you're absolutely right of course. I remember your Ham Radio
article very well.

What I should have said was "if you intend to use coax feed..."

It's also true that coax feed is not as easy as it looks, because of the
"hot feedline" problem. In many ways a small ground-mounted ATU is
better. Since the half-square is a monoband antenna, the ATU is "set and
forget" and it's very easy to get going as you say.

Well, not quite monoband... with different ATU settings, a 40m half-square
will also work as an end-fed half-wave "inverted U" for short skip on 80m.


I ran this antenna for
years, and I had the mistaken notion that it was a "half-square". Wonders
never cease...I would have thought the editor of the mag, a seemingly
knowledgable fellow, would have caught my mistake.

very big grin, tongue in cheek

Even editors can have a bad day... looks like yesterday was one of them
:-)


--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

If you were to use aluminum for the verticals rather than wire, what would
the shortening factor be?

Doug


"Ian White GM3SEK" wrote in message
...
hasan schiers wrote:

"Ian White GM3SEK" wrote in message
...

Original poster said:

I was thinking
of feeding it at the corner, I think it will be close to 50 ohms.

Ian said:

That's where it must be fed. Anywhere else, and it won't act as a
half-square (except the other top corner of course).

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

eh?

Fed at the bottom via a parallel tuned circuit works, no ? You can see my
article in Ham Radio Magazine from many years ago on how to feed it that
way, (which is really the classical feed for this antenna...the corner
fed,
with all of it's inherent problems came along a lot later, AFAIK)

Simply use a parallal tuned circuit at the base of either vertical, and
tap
up from the bottom (ground side) of the coil for 50 ohms. The tuning cap
for
the coil can be a piece of coax (at "x" pf per foot).

Sorry, Hasan, you're absolutely right of course. I remember your Ham Radio
article very well.

What I should have said was "if you intend to use coax feed..."

It's also true that coax feed is not as easy as it looks, because of the
"hot feedline" problem. In many ways a small ground-mounted ATU is
better. Since the half-square is a monoband antenna, the ATU is "set and
forget" and it's very easy to get going as you say.

Well, not quite monoband... with different ATU settings, a 40m half-square
will also work as an end-fed half-wave "inverted U" for short skip on 80m.


I ran this antenna for
years, and I had the mistaken notion that it was a "half-square". Wonders
never cease...I would have thought the editor of the mag, a seemingly
knowledgable fellow, would have caught my mistake.

very big grin, tongue in cheek

Even editors can have a bad day... looks like yesterday was one of them
:-)


--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

DOUGLAS SNOWDEN wrote:
If you were to use aluminum for the verticals rather than wire, what
would the shortening factor be?


If it is end-fed, as Hasan recommends[*] then the exact height of the
vertical parts wouldn't matter much.

The main difference would be in the high-angle radiation from the
horizontal part. That radiation is roughly canceled, but in a
half-square the cancellation is never complete... which means any
differences would be very hard to hear.

But be aware that the voltage at the bottom of the far end is very high
indeed. This is no place to use a metal ground post and a thin sleeve of
plastic pipe! I've drilled holes through thick PVC support blocks by
voltage-feeding a half-wave vertical, and this open end is worse.


--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek