I'm considering installing an inverted V 40 meter dipole under the eaves of my
house. There is room for a longer arm on one side than the other.

1) Would I be better off making each arm as long as possible and adding whatever
matching circuit is required?

2) Should I make both sides equal to the shorter arm even if this makes the
antenna too short to self resonate?

3) Should I make both sides equal in case there is sufficient length to allow
the antenna to self resonate.

Sorry for the complexity of the question.

Thanks for any help.

Ron W4TQT

Hi Ron -

Some comments below...

"Ron" wrote in message
news
I'm considering installing an inverted V 40 meter dipole under the eaves
of my
house. There is room for a longer arm on one side than the other.

1) Would I be better off making each arm as long as possible and adding
whatever
matching circuit is required?

You didn't say what actual dimensions you have available, or whether
the total gets you up to 66' (or so). But it sounds like your shorter side
is less than 33'. No, don't use excessive (for resonance) length, if you
intend to have a resonant monobander.

2) Should I make both sides equal to the shorter arm even if this makes
the
antenna too short to self resonate?

No. If your short side is less than 33', make it as long as you can.
Then trim the long side for lowest SWR at your desired center frequency.
There should be no problem at all with unequal sides, within reason.
In fact, unbalancing the sides physically can sometimes improve the
electrical balance, and/or minimize SWR, if done correctly.

3) Should I make both sides equal in case there is sufficient length to
allow
the antenna to self resonate.

That would be the "classical" way to do it; and if you got a good match,
you'd be done.

But if you like fine tuning, try adding a foot to one side, and measure
center freq and SWR. Then put the extra foot over on the other side, and
again measure center freq and SWR. The center freqs should be the same,
or very close. But if one configuration shows lower SWR, that is telling
you that a physical imbalance in that direction will improve your match.

My 40/80 trap dipole works best on 80 when one side is about 3' longer
than the other!

73, Ed W6LOL

Sorry for the complexity of the question.

Thanks for any help.

Ron W4TQT

Why not take a look at the Carolina Windom from Radio Works. It might meet
your requirements.


--
Steve Ellington N4LQ.
"Roy Lewallen" wrote in message
...
There won't be much practical difference in radiation from the antenna
itself among the choices. But it's much more difficult to suppress
feedline radiation when the sides have different lengths. Since the
feedline is likely to be in close proximity to house wiring and
appliances, it's probably a good idea to keep feedline radiation to a
minimum. This means using a current balun at the feedpoint, and possibly
another a quarter wavelength or so farther down the feedline. People
using off-center fed dipoles have reported difficulty in suppressing
feedline radiation even with fairly decent baluns, but it should be
possible. Of course, if the asymmetry isn't great, there shouldn't be
much of a problem. The advantage to making the overall length closer to
resonance is a higher feedpoint impedance (which you might be able to
get close enough to 50 ohms to obviate matching) and a bit greater
bandwidth. The trade between this and the potential difficulty in
suppressing feedline radiation is up to you to make.

What I'd probably do is make the dipole symmetrical, match it at the
feedpoint with lumped components, and feed it with coax via a current
balun at the feedpoint. But that's only one of a number of possible, and
about equally workable, solutions.

Roy Lewallen, W7EL

Ron wrote:
I'm considering installing an inverted V 40 meter dipole under the eaves
of my house. There is room for a longer arm on one side than the other.

1) Would I be better off making each arm as long as possible and adding
whatever matching circuit is required?

2) Should I make both sides equal to the shorter arm even if this makes
the antenna too short to self resonate?

3) Should I make both sides equal in case there is sufficient length to
allow the antenna to self resonate.

Sorry for the complexity of the question.

Thanks for any help.

Ron W4TQT

"N4LQ" wrote
Why not take a look at the Carolina Windom from Radio Works. It might meet
your requirements.
=====================================

Of course it will. Why do nitpicking busy-bodies stir up worries about
radiation from feed-lines? It's never wasted.

Feedline radiation may disappear in unknown directions, but, even when a
dipole is centre-fed, the radiation pattern in the midst of the usual
environmental cluttering uncertainty, and the manner in which the feedline
is led away from then antenna, the whole thing is always a matter of
guesswork.

As the antenna is non-rotatable it doesn't matter very much what the very
uncertain distorted radiation pattern is anyway.

Just erect the antenna in the best possible way you can manage in the
limited space available and see what happens. Most likely you will not be
disappointed in its performance.

Good DX !
---
Reg, G4FGQ

Thanks, Reg. I now can proudly add "Busy-body" to my long-held titles of
Reg's Old Wife and Nitpicker. I'm honored.

Roy Lewallen, W7EL

Reg Edwards wrote:
"N4LQ" wrote

Why not take a look at the Carolina Windom from Radio Works. It might meet
your requirements.

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

Of course it will. Why do nitpicking busy-bodies stir up worries about
radiation from feed-lines? It's never wasted.
. . .

On Fri, 11 Jul 2003 18:18:49 -0700, Roy Lewallen
wrote:

Thanks, Reg. I now can proudly add "Busy-body" to my long-held titles of
Reg's Old Wife and Nitpicker. I'm honored.

Roy Lewallen, W7EL

Reg Edwards wrote:
"N4LQ" wrote

Why not take a look at the Carolina Windom from Radio Works. It might meet
your requirements.

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

Of course it will. Why do nitpicking busy-bodies stir up worries about
radiation from feed-lines? It's never wasted.
. . .

Hi Roy,

Nevermind that most who post here that suffer from feed-line radiation
can now rest at ease with their plight knowing that the problem is
their own nitpicking (Punchinello has obviously never kissed a mike
like Cecil - that or his glass of wine insulates/anesthetizes his soft
tissues).

73's
Richard Clark, KB7QHC

On Sat, 12 Jul 2003 01:11:52 GMT, Ron wrote:

What I did not mention is that is that I live in a condo with antenna
restrictions. But I figure if I put the antenna under the eaves of the house, it
will be virtually invisible except at the apex where the the feed wires enter
the attic. I have purchased a B1-5K balun from Radio Works and plan to use it on
the attic side of the wall.

Ever thought of using a tuned loop (very small like a gamma match, or
similar) driving a rain gutter? You might be able to hide the
components behind it under the eaves.

I am now using a Buddipole in the attic and it works, but I am hoping to get
better radiation (and less telephone and TV RFI) by using a full length dipole
and getting it at least a little further away from attic wiring, heating/AC
ducts, etc. Also I am afraid to run more than 100 watts, not only due to RFI
concerns, but from a fire safety standpoint as well.

This, in parts of Britain, is called nit-picking (British nits seem to
be unrelated to photometric nits). Anyway, any coupling from feed
line radiation into nearby susceptible wiring can be suppressed with a
current BalUn. Given the proximity of so many opportunities to
distort the field, you are sure to suffer imbalance (the leading
contributor to Common Mode). If these problems arise from the
radiator's field, distance is the best solution.

I just bought an Autek antenna analyzer which I think will come in handy. At
least with a feed point in the attic, I should be able to make impedance
measurements easily.

So I would like to use a Carolina Windom, but my situation will not allow it. We
have lots of tall trees in the back yard and I often look at them longingly, but
realistically I think I'm just day dreaming, hi. Anyway, thanks for all replies.

Ron

Hi Ron,

A thin wire with beige coloring could be nearly invisible (the keyword
being "nearly" ... depends on the visual acuity of the antennazis).

73's
Richard Clark, KB7QHC

Not only that, I always considered RF voltage that bit me on the lip as wasted!

Dick


Roy Lewallen wrote:

Thanks, Reg. I now can proudly add "Busy-body" to my long-held titles of
Reg's Old Wife and Nitpicker. I'm honored.

Roy Lewallen, W7EL

Reg Edwards wrote:
"N4LQ" wrote

Why not take a look at the Carolina Windom from Radio Works. It might meet
your requirements.

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

Of course it will. Why do nitpicking busy-bodies stir up worries about
radiation from feed-lines? It's never wasted.
. . .

"Reg Edwards" wrote in message ...
"N4LQ" wrote
Why not take a look at the Carolina Windom from Radio Works. It might meet
your requirements.
=====================================

Of course it will. Why do nitpicking busy-bodies stir up worries about
radiation from feed-lines? It's never wasted.

It might not live up to it's full potential though. "Stunted RF
syndrome" I'd rather have the rf radiated at 40 ft where the antenna
is, rather than the line which ranges from 40 ft down to ground level.
The ground losses of a radiator laying on the ground shouldn't be
ignored. :-) Also, the ground clutter factor. Yes, RF does have many
Superman qualities, such as traveling faster than a speeding bullet,
and being able to travel through most walls at will. But some walls
are metal or even "gasp" lead, and this would prevent the RF from full
exposure to the ether in that direction. But the most important reason
is it whacks out my radios, puters, and other gadgets and causes them
to malfunction in strange and mysterious ways. Also, I don't drink
much wine anymore, so I'm not "medicated" against possible mike burns.
MK

Mark said,

I'd rather have the rf radiated at 40 ft where
the antenna is , rather than the line which
ranges from 40 ft down to ground level.

==============================
Mark, Roy,

Of course you would ! So would everybody else.

But iustead of making a federal case out of it, if the question is read
again it will be seen to obtain a longer antenna length and something nearer
to resonance, Ron is being forced to compromise.

And if there IS a bit of RF inside the house most likely it will be due to
the antenna's near field anyway. There's only one way to find out - suck it
and see.
---
Reg.