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Old November 23rd 14, 09:39 PM posted to rec.radio.amateur.antenna
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Default Another antenna curiosity

gareth wrote:
wrote in message
...
gareth wrote:

The Slim Jim or the J-Pole?


Neither of those are foled.


Now I _KNOW_ that you are nothing but an ignorant abusive troll,
mouthing infantile obscenities in order to make yourself the centre of
attention


Just what is so abusive about pointing out the fact that neither a
slim jim nor a j-pole are folded antennas?



--
Jim Pennino
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Old November 23rd 14, 11:21 PM posted to rec.radio.amateur.antenna
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Default Another antenna curiosity



"gareth" wrote in message ...

wrote in message
...
gareth wrote:

The Slim Jim or the J-Pole?


Neither of those are foled.


Now I _KNOW_ that you are nothing but an ignorant abusive troll,
mouthing infantile obscenities in order to make yourself the centre of
attention


PLONK!


You asked "the Slim Jim or the J-pole?"
Nope. He's talking about essentially a vertical made out of half of a
folded dipole. And that vertical part itself is folded over.

That's quite a bit different.

Personally, I don't get the ignorant abusive troll part from his response.



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Old November 23rd 14, 11:48 PM posted to rec.radio.amateur.antenna
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Default Another antenna curiosity

Wayne wrote:


"gareth" wrote in message ...

wrote in message
...
gareth wrote:

The Slim Jim or the J-Pole?

Neither of those are foled.


Now I _KNOW_ that you are nothing but an ignorant abusive troll,
mouthing infantile obscenities in order to make yourself the centre of
attention


PLONK!


You asked "the Slim Jim or the J-pole?"
Nope. He's talking about essentially a vertical made out of half of a
folded dipole. And that vertical part itself is folded over.

That's quite a bit different.

Personally, I don't get the ignorant abusive troll part from his response.


It is a knee jerk reaction to someone that has called him on false
statements in the past.


--
Jim Pennino
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Old November 24th 14, 12:27 PM posted to rec.radio.amateur.antenna
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Posts: 550
Default Another antenna curiosity

On 11/23/2014 2:22 PM, Brian Howie wrote:
In message , John S
writes
On 11/23/2014 11:17 AM, Wayne wrote:


"John S" wrote in message ...

I like antennas that are short-circuited DC-wise. Mainly because, at
one time I had a radio on a vertical and lightning struck about a mile
away and blocked my receiver for several seconds. Of course, not all
radios have a floating input, but, it impressed me.

So, I "invented" the folded unipole which would match to a 50 ohm feed.

Any interest?

Yes.


By the way, Wayne, my interests in antennas have recently been in the
70cm band (specifically 434MHz) where there are numerous cheap modules
to play with. They have only 1 or so mW output and are illegal in the
US for unlicensed operation except under strict limitations. However,
with a license, I can do what I wish as long as I comply with the
regulations. My software always sends my call letters at each
transmission, for example.

As for the folded unipole, first imagine a normal unipole. Remember
that the feed resistance is about 30 or so ohms, yes? So, the
recommendation is to droop the radials to about -45 degrees. This
raises the feed resistance to about 50 ohms.

Now, the folded unipole has a higher feed resistance than we want.
Hmmmm.. what if we RAISE the radials to compensate? Yeah, stupid, right?

It works, and I have a model here which exhibits SWR so low I cannot
measure it except with a vector voltmeter.

I am not recommending this for the average amateur because tuning the
antenna is a bit troublesome for many. It is a bit easier to adjust a
normal unipole's length than a folded unipole's length. That's why I
haven't pushed it.



I suppose it's a bit like a gamma matched vertical except the gamma goes
all the way to the top.

Brian


I think it could be viewed that way, except there is no gamma inductance
to contend with.
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