On Sat, 20 Aug 2005 11:28:52 -0700, John Smith
wrote:

nospam:

That cb antenna (with the 3 dipoles arranged so as to go omni/directional)
was called a "scanner", made by antenna specialists I believe (reed
switches in a relay box control the elements.)

Yep thats it, got stuck for a name.

I cut one down, along with the phasing harness to the center of the 10
meter band, works great! And you are correct, the three 120 degree spaced
vertical dipoles are fed in phase for omni-pattern.

Many years ago I help a ham friend (now SK) set up a foursquare. that
four vertical monopoles with goundplane with phasing feed for gain and
directionality. It was a very good antenna for 20M.

Early in my commercial career I worked part time for an AM BCB station
and would help with antenna tuning for directional pattern. Imagine
three big (300ft) towers in a field with about that much space between
them in a line. The feed and phasing coils were BIG, the usual
pattern was cartioid with the weak null facing the atlantic ocean to
the southeast. Just a bigger version of many phased arrays I'd see
in my commercial career.

Allison
KB1GMX

Me wrote:
In article .com,
wrote:

Us Amateurs don't have a lot of experience

That's why they call you "Amateurs".....the Professional Radio Engineers
understand perfectly what the OP was talking about, and exactly why, and
how, this type of antenna system is used in the real world of
communications, both fixed and mobile.

Me who has been around the biz, since almost before Moses.....

I am glad they call me an Amateur, because that is what I am. The
word Amateur is in the name of this Newsgroup. It is obvious
Professional Radio Engineers would understand what Reg was talking
about, but this is an Amateur Newsgroup. Why don't you go to the
Professional Antenna Designer Newsgroup (if there is one) and ask the
question that Reg did? I don't think they would all understand
perfectly, but I may be wrong, because I am an amateur. By the way,
are you an Amateur Radio Operator?
Gary N4AST

"Richard Clark" wrote in message
...
On Fri, 19 Aug 2005 20:21:38 +0000 (UTC), "Reg Edwards"
wrote:

Is the radiation pattern in the horizontal plane perfectly
omni-directional?

No (and begs the question, what IS perfect?).

On Fri, 19 Aug 2005 22:00:33 +0000 (UTC), "Reg Edwards"
wrote:

What is the radiation pattern in the horizontal plane?

Just like for the two lobes of a dipole, three lobes for a tripole.

Also what is the equivalent load impedance between each of the line
wires.

35 Ohms.

Hardly comes to the class of pageantry in:
On Tue, 16 Aug 2005 16:15:10 +0000 (UTC), "Reg Edwards"
wrote:

Is there anybody about who still imagines that an SWR meter, located
... on the other side of the tuner, indicates
SWR on the transmission line between transmitter and the antenna?

Anybody indeed? Name someone else other than yourself, Reg. Jeesh....

Time to throw in the last spade of earth and say Amen.

73's
Richard Clark, KB7QHC

I ran EZNEC on what I think is an equivalent arrangement, and got a gain
max/min ratio of about 4db. Got an impedance of 29 Ohms. With multiple
sources, I have trouble visualizing what that means. That may actually be 87
Ohms line to line.

Tam/WB2TT

On Sat, 20 Aug 2005 20:00:16 -0400, "Tam/WB2TT"
wrote:

I have trouble visualizing what that means.

Hi Tam,

What do you mean by that? You have a source pushing current into an
element against a counterpoise, an active one albeit, but all
counterpoises support current too (hence the symmetry of resistance).
Just another condition of the ENTIRE structure radiating energy (where
some would have energy cancelled rather than the power product into a
remote load).

Yes, the three leaf trifoil is not very pronounced, and only below an
elevation or 45 degrees or so. However, Reg introduced this with the
strong suggestion of perfection. Perhaps his usual indirection. ;-)

A 4-phase antenna shows a similar lobing to a smaller degree, and a
5-phase antenna is for all practical purposes circular.

I had to solve a problem like this a couple of years ago with a design
for the Army to test their Helicopter pilots for mental alertness.
This involved building a uniform field of even illumination over a
visual angle of 180 degrees horizontal and 90 degrees vertical
(roughly the entire field of view). I was tasked to present no more
variation than a couple of percent ripple. It took about 100 light
sources 1 cM from the eyes.

73's
Richard Clark, KB7QHC

"Richard Clark" wrote in message
...
On Sat, 20 Aug 2005 20:00:16 -0400, "Tam/WB2TT"
wrote:

I have trouble visualizing what that means.

Hi Tam,

What do you mean by that? You have a source pushing current into an
element against a counterpoise, an active one albeit, but all
counterpoises support current too (hence the symmetry of resistance).
Just another condition of the ENTIRE structure radiating energy (where
some would have energy cancelled rather than the power product into a
remote load).

Yes, the three leaf trifoil is not very pronounced, and only below an
elevation or 45 degrees or so. However, Reg introduced this with the
strong suggestion of perfection. Perhaps his usual indirection. ;-)

A 4-phase antenna shows a similar lobing to a smaller degree, and a
5-phase antenna is for all practical purposes circular.

I had to solve a problem like this a couple of years ago with a design
for the Army to test their Helicopter pilots for mental alertness.
This involved building a uniform field of even illumination over a
visual angle of 180 degrees horizontal and 90 degrees vertical
(roughly the entire field of view). I was tasked to present no more
variation than a couple of percent ripple. It took about 100 light
sources 1 cM from the eyes.

73's
Richard Clark, KB7QHC

Hi Richard,

My main problem was interpreting what EZNEC meant when it told me the
impedance was 29 Ohms at resonance. Missed the fact that it displays the Z
for each generator independently. 29 is the impedance to neutral. So, that
makes it 87 Ohms line to line. I did this in free space. There is no NET
current in the neutral.

Tam

On Sun, 21 Aug 2005 12:03:00 -0400, "Tam/WB2TT"
wrote:

My main problem was interpreting what EZNEC meant when it told me the
impedance was 29 Ohms at resonance. Missed the fact that it displays the Z
for each generator independently. 29 is the impedance to neutral. So, that
makes it 87 Ohms line to line. I did this in free space. There is no NET
current in the neutral.

Hi Tam,

I took the more practical (amusing given the absurd complication of a
3-phase RF source) route of putting the antenna ¼ above earth.

73's
Richard Clark, KB7QHC

In article .com,
wrote:

By the way, are you an Amateur Radio Operator?
Gary N4AST


Since 1964


Me

Me wrote:
In article .com,
wrote:


By the way, are you an Amateur Radio Operator?
Gary N4AST



Since 1964


Me

Awe! A newcomer!

You must be QCWA*2 minimum to post on this list. :-)

Me wrote:
In article .com,
wrote:

By the way, are you an Amateur Radio Operator?
Gary N4AST


Since 1964


Me

Well Me, as for me, Amateur since 1963, professional radio engineer,
never. I did install some cb antennas during the early 1970's and got
paid, so I may be a professional antenna installer? Hope by these acts
I didn't give up my Amateur status. Was in college at the time and did
not have much $$. Why don't you give your call?
Gary N4AST

In article .com,
wrote:

Me wrote:
In article .com,
wrote:

By the way, are you an Amateur Radio Operator?
Gary N4AST


Since 1964


Me

Well Me, as for me, Amateur since 1963, professional radio engineer,
never. I did install some cb antennas during the early 1970's and got
paid, so I may be a professional antenna installer? Hope by these acts
I didn't give up my Amateur status. Was in college at the time and did
not have much $$. Why don't you give your call?
Gary N4AST


I am available on 14292.0Khz (20 Meters) daytime, during the winter
months ( Sept - May) and 3840Khz (75 meters) most evenings after 10Pm
local....

Stop by for a visit sometime.....

Me