Another antenna curiosity
 

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?

Another antenna curiosity
 

"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.

Another antenna curiosity
 

"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.

The Slim Jim or the J-Pole?

Another antenna curiosity
 

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.

Another antenna curiosity
 

On 11/23/2014 11:24 AM, gareth 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.

The Slim Jim or the J-Pole?

I invented neither, Gareth. And note that my "invented" is within
quotes. I actually invented nothing.

If you are interested, please see additional posts.

Another antenna curiosity
 

gareth 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.

The Slim Jim or the J-Pole?

Neither of those are foled.



--
Jim Pennino

Another antenna curiosity
 

"John S" wrote in message ...

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.

Interesting.
But, I would expect the folded unipole to have a feedpoint of about 150 ish
ohms over perfect ground.

Is that the antenna that you have built and tested?

Another antenna curiosity
 

On 11/23/2014 12:53 PM, Wayne wrote:


"John S" wrote in message ...

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.

Interesting.
But, I would expect the folded unipole to have a feedpoint of about 150
ish ohms over perfect ground.

Yes, approximately, but using 4 radials rather than perfect ground. Feed
point resistance approximately 150 ohms as you say.

Is that the antenna that you have built and tested?

No. Picture the folded unipole with the feedpoint resistance you imagine
with 4 radials. Now, raise the angle of the radials about 23 or 25
degrees to get the feed point resistance desired.

Remember that the typical ground plane needs a droop of about 45 degrees
to raise its feed point resistance, so we are doing just the opposite
here. It will lower the feed point resistance.

I have an EZNEC file you may have, when you are ready.

Another antenna curiosity
 

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!

Another antenna curiosity
 

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
--
Brian Howie