Follow up to Spike ;Bent dipoles?
 

Spike recently commented upon his success with DX by implementing at
the base of his vertical antenna a fan
of 300 ground wires pointing in the direction that he wished to work.

I've not seen my suggestion before, but why could one not just have
a 1/4 wave vertical, with the other 1/4 wave making up the dipole
being rotatable for the desired direction of working?

Follow up to Spike ;Bent dipoles?
 

"gareth" wrote:
Spike recently commented upon his success with DX by implementing at
the base of his vertical antenna a fan
of 300 ground wires pointing in the direction that he wished to work.

I've not seen my suggestion before, but why could one not just have
a 1/4 wave vertical, with the other 1/4 wave making up the dipole
being rotatable for the desired direction of working?

***Project Shun Notice***
Gareth Alun Evans G4SDW has been placed under a global shunning order by
Project Shun for his continual, deranged trolling.
Please help us make Usenet better by not responding to his malicious and
lunatic postings.
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***end***

--
STC // M0TEY // twitter.com/ukradioamateur

Follow up to Spike ;Bent dipoles?
 

On 11/28/2015 4:11 PM, gareth wrote:
Spike recently commented upon his success with DX by implementing at
the base of his vertical antenna a fan
of 300 ground wires pointing in the direction that he wished to work.

I've not seen my suggestion before, but why could one not just have
a 1/4 wave vertical, with the other 1/4 wave making up the dipole
being rotatable for the desired direction of working?

One could.

Follow up to Spike ;Bent dipoles?
 

On 28/11/2015 22:11, gareth wrote:
Spike recently commented upon his success with DX by implementing at
the base of his vertical antenna a fan of 300 ground wires pointing
in the direction that he wished to work.

I've not seen my suggestion before, but why could one not just have a
1/4 wave vertical, with the other 1/4 wave making up the dipole being
rotatable for the desired direction of working?

This was covered in, IIRC, Pat Hawkers Technical Topics many years ago.
The Americans had done some research on this very topic during the
Vietnam war, if one bends a vertical dipole so that the two elements are
at right angles to each other it is possible it would seem to get some
directivity in the direction of the horizontal element.



--
Extend ****s law - make 'em wear a cheat sheet 24/7

Follow up to Spike ;Bent dipoles?
 

"Fred Roberts" wrote in message
...
On 28/11/2015 22:11, gareth wrote:
Spike recently commented upon his success with DX by implementing at
the base of his vertical antenna a fan of 300 ground wires pointing
in the direction that he wished to work.

I've not seen my suggestion before, but why could one not just have a
1/4 wave vertical, with the other 1/4 wave making up the dipole being
rotatable for the desired direction of working?

This was covered in, IIRC, Pat Hawkers Technical Topics many years ago.
The Americans had done some research on this very topic during the Vietnam
war, if one bends a vertical dipole so that the two elements are at right
angles to each other it is possible it would seem to get some directivity
in the direction of the horizontal element.

Thinking about how drooping the radials on a ground plane brings
the feed impedance from 35 up to 50 ohms, I presume that bending a dipole
has
the same type of effect of reducing down from 72 ohms?

Follow up to Spike ;Bent dipoles?
 

"gareth" wrote:
"Fred Roberts" wrote in message
...
On 28/11/2015 22:11, gareth wrote:
Spike recently commented upon his success with DX by implementing at
the base of his vertical antenna a fan of 300 ground wires pointing
in the direction that he wished to work.

I've not seen my suggestion before, but why could one not just have a
1/4 wave vertical, with the other 1/4 wave making up the dipole being
rotatable for the desired direction of working?

This was covered in, IIRC, Pat Hawkers Technical Topics many years ago.
The Americans had done some research on this very topic during the Vietnam
war, if one bends a vertical dipole so that the two elements are at right
angles to each other it is possible it would seem to get some directivity
in the direction of the horizontal element.

Thinking about how drooping the radials on a ground plane brings
the feed impedance from 35 up to 50 ohms, I presume that bending a dipole
has
the same type of effect of reducing down from 72 ohms?

***Project Shun Notice***
Gareth Alun Evans G4SDW has been placed under a global shunning order by
Project Shun for his continual, deranged trolling.
Please help us make Usenet better by not responding to his malicious and
lunatic postings.
With thanks, Team Project Shun.
***end***

--
STC // M0TEY // twitter.com/ukradioamateur

Follow up to Spike ;Bent dipoles?
 

On 29/11/2015 12:25, gareth wrote:

Thinking about how drooping the radials on a ground plane brings the
feed impedance from 35 up to 50 ohms, I presume that bending a
dipole has the same type of effect of reducing down from 72 ohms?

A good point and something I hadn't considered!



--
Extend ****s law - make 'em wear a cheat sheet 24/7

Follow up to Spike ;Bent dipoles?
 

On 29/11/2015 12:18, Fred Roberts wrote:
On 28/11/2015 22:11, gareth wrote:

Spike recently commented upon his success with DX by implementing at
the base of his vertical antenna a fan of 300 ground wires pointing
in the direction that he wished to work.

I've not seen my suggestion before, but why could one not just have a
1/4 wave vertical, with the other 1/4 wave making up the dipole being
rotatable for the desired direction of working?

This was covered in, IIRC, Pat Hawkers Technical Topics many years ago.
The Americans had done some research on this very topic during the
Vietnam war, if one bends a vertical dipole so that the two elements are
at right angles to each other it is possible it would seem to get some
directivity in the direction of the horizontal element.

Gareth is missing the point of the multitude of radials, which are there
essentially to get the ground in the radial arc looking like a sheet of
metal (and thus lowering the angle of the main lobe). Ideally they
should run out to 2.5 lambda, but I didn't have enough wire :-(

The bent arm of the dipole can't do that, and is essentially a
convenient place to attach the coax outer.


--
Spike

"Crime butchers innocence to secure a throne, and innocence struggles
with all its might against the attempts of crime"

- Maximilien Robespierre

Follow up to Spike ;Bent dipoles?
 

"Fred Roberts" wrote in message
...
On 28/11/2015 22:11, gareth wrote:
Spike recently commented upon his success with DX by implementing at
the base of his vertical antenna a fan of 300 ground wires pointing
in the direction that he wished to work.

I've not seen my suggestion before, but why could one not just have a
1/4 wave vertical, with the other 1/4 wave making up the dipole being
rotatable for the desired direction of working?

This was covered in, IIRC, Pat Hawkers Technical Topics many years ago.
The Americans had done some research on this very topic during the Vietnam
war, if one bends a vertical dipole so that the two elements are at right
angles to each other it is possible it would seem to get some directivity
in the direction of the horizontal element.


As I'm sure we both know, if a horizontal half wave dipole is turned so the
element runs east to west, the maximum radiation will be north and south,
with nulls to the east and west.
If the dipole is now turned vertically, the nulls would be upwards and
downwards and the horizontal radiation would be omni-directional.
I've not tried this, but my gut feeling is that if the elements were at
right angles you would get a combination of the two radiation patterns,
hence some degree of directivity in the form of a null in the direction the
horizontal element was pointing.
--
;-)
..
73 de Frank Turner-Smith G3VKI - mine's a pint.
..
http://turner-smith.uk

Follow up to Spike ;Bent dipoles?
 

In message , FranK Turner-Smith G3VKI
writes
"Fred Roberts" wrote in message
...
On 28/11/2015 22:11, gareth wrote:
Spike recently commented upon his success with DX by implementing at
the base of his vertical antenna a fan of 300 ground wires pointing
in the direction that he wished to work.

I've not seen my suggestion before, but why could one not just have a
1/4 wave vertical, with the other 1/4 wave making up the dipole being
rotatable for the desired direction of working?

This was covered in, IIRC, Pat Hawkers Technical Topics many years
ago. The Americans had done some research on this very topic during
the Vietnam war, if one bends a vertical dipole so that the two
elements are at right angles to each other it is possible it would
seem to get some directivity in the direction of the horizontal element.


As I'm sure we both know, if a horizontal half wave dipole is turned so
the element runs east to west, the maximum radiation will be north and
south, with nulls to the east and west.
If the dipole is now turned vertically, the nulls would be upwards and
downwards and the horizontal radiation would be omni-directional.
I've not tried this, but my gut feeling is that if the elements were at
right angles you would get a combination of the two radiation patterns,
hence some degree of directivity in the form of a null in the direction
the horizontal element was pointing.

Isn't it the other way around?

Think what happens if you start with the radiation diagram of a straight
vertical dipole, and then consider what happens when you progressively
raise the lower leg. The once-straight halfwave dipole starts to form a
V, and in the direction of the legs of the V, the radiation will start
to become somewhat more concentrated. Away from the legs of the V, the
radiation starts to become more spread out. However, I don't think you
can go too far with this reasoning before you start to lose the slight
amount of benefit you obtained.
--
Ian