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Old August 1st 03, 10:12 PM
Paul Burridge
 
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Default Super-whippy whip antennas


Hi chaps,

Can anyone suggest a suitable material from which to make an
ultra-flexible mobile whip antenna say about 3 to 4 feet long. I need
something that can be bent to 90 degrees at a very small radius and
still return to reasonable straightness.

Thanks,

p.
--

"I believe history will be kind to me, since I intend
to write it." - Winston Churchill

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Old August 1st 03, 11:53 PM
JGBOYLES
 
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Default

Can anyone suggest a suitable material from which to make an
ultra-flexible mobile whip antenna say about 3 to 4 feet long. I need
something that can be bent to 90 degrees at a very small radius and
still return to reasonable straightness.


Sure, get some 1/4 inch fiberglass rod, loosely helix some #22 wire up the
length, and secure with some heat-shrink tubing. You can bend this into a near
circle.
73 Gary N4AST
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Old August 1st 03, 11:53 PM
JGBOYLES
 
Posts: n/a
Default

Can anyone suggest a suitable material from which to make an
ultra-flexible mobile whip antenna say about 3 to 4 feet long. I need
something that can be bent to 90 degrees at a very small radius and
still return to reasonable straightness.


Sure, get some 1/4 inch fiberglass rod, loosely helix some #22 wire up the
length, and secure with some heat-shrink tubing. You can bend this into a near
circle.
73 Gary N4AST
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Old August 2nd 03, 11:11 AM
Paul Burridge
 
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Default

On Sat, 02 Aug 2003 03:25:47 GMT, Active8
wrote:

In article [email protected], lid says...
Paul Burridge wrote:
Hi chaps,

Can anyone suggest a suitable material from which to make an
ultra-flexible mobile whip antenna say about 3 to 4 feet long. I need
something that can be bent to 90 degrees at a very small radius and
still return to reasonable straightness.


I think thin piano wire will give the best results. Place a lot of them
in a flexible tube to gain some thickness and have them silvered for
conductivity - or add a stranded copper wire.

Spring metal strip may also work, especially if you can manage some type
of hinge at the base that allows it to turn when sideways force is
exerted, or if the force is in one plane.


Thomas


what is a tight bend? music wire comes in diff sizes and the number in
the tube and how tightly the tube conforms to it will have an effect on
the flexibility.


Yeah, sorry chaps, I should have better defined what I meant by 'very
small radius'. I compete in radio-controlled model battles, so the
model stands to get fipped upside down from time to time in a very
bruising environment and it already has a very low ground-clearance,
so using a spring as a base mounting won't help much, I'm afraid.
We're talking about radiuses of as little as 5mm! How about the
specific grade of stainless steel in wire form that springs are made
from? I know where I can get hold of some of that....
--

"I believe history will be kind to me, since I intend
to write it." - Winston Churchill
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Old August 2nd 03, 11:11 AM
Paul Burridge
 
Posts: n/a
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On Sat, 02 Aug 2003 03:25:47 GMT, Active8
wrote:

In article [email protected], lid says...
Paul Burridge wrote:
Hi chaps,

Can anyone suggest a suitable material from which to make an
ultra-flexible mobile whip antenna say about 3 to 4 feet long. I need
something that can be bent to 90 degrees at a very small radius and
still return to reasonable straightness.


I think thin piano wire will give the best results. Place a lot of them
in a flexible tube to gain some thickness and have them silvered for
conductivity - or add a stranded copper wire.

Spring metal strip may also work, especially if you can manage some type
of hinge at the base that allows it to turn when sideways force is
exerted, or if the force is in one plane.


Thomas


what is a tight bend? music wire comes in diff sizes and the number in
the tube and how tightly the tube conforms to it will have an effect on
the flexibility.


Yeah, sorry chaps, I should have better defined what I meant by 'very
small radius'. I compete in radio-controlled model battles, so the
model stands to get fipped upside down from time to time in a very
bruising environment and it already has a very low ground-clearance,
so using a spring as a base mounting won't help much, I'm afraid.
We're talking about radiuses of as little as 5mm! How about the
specific grade of stainless steel in wire form that springs are made
from? I know where I can get hold of some of that....
--

"I believe history will be kind to me, since I intend
to write it." - Winston Churchill
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Old August 2nd 03, 04:40 PM
cpemma
 
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Default

Paul Burridge wrote:
On Sat, 02 Aug 2003 03:25:47 GMT, Active8
wrote:

In article [email protected], lid
says...
Paul Burridge wrote:
Hi chaps,

Can anyone suggest a suitable material from which to make an
ultra-flexible mobile whip antenna say about 3 to 4 feet long. I
need something that can be bent to 90 degrees at a very small
radius and still return to reasonable straightness.

I think thin piano wire will give the best results. Place a lot of
them in a flexible tube to gain some thickness and have them
silvered for conductivity - or add a stranded copper wire.

Spring metal strip may also work, especially if you can manage some
type of hinge at the base that allows it to turn when sideways
force is exerted, or if the force is in one plane.


Thomas


what is a tight bend? music wire comes in diff sizes and the number
in the tube and how tightly the tube conforms to it will have an
effect on the flexibility.


Yeah, sorry chaps, I should have better defined what I meant by 'very
small radius'. I compete in radio-controlled model battles, so the
model stands to get fipped upside down from time to time in a very
bruising environment and it already has a very low ground-clearance,
so using a spring as a base mounting won't help much, I'm afraid.
We're talking about radiuses of as little as 5mm! How about the
specific grade of stainless steel in wire form that springs are made
from? I know where I can get hold of some of that....
"I believe history will be kind to me, since I intend
to write it." - Winston Churchill


The alloy is Type 301 (17% chromium, 7% nickel stainless steel) hard drawn
wire, or even better is a 17/7PH (precipitation hardening) grade that our
firm once produced for tank aerials, that also may take a few knocks.

Both (especially the PH grade) need a final heat-treatment (420C for a few
minutes IIRC) for ultimate spring properties, but to get such a tight bend
you'd need quite a thin wire. It's a matter of the proof strain or limit of
proportionality, how much the outer skin can stretch without taking a
permanent set, compared to the neutral central axis, on the bend.



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Old August 2nd 03, 04:40 PM
cpemma
 
Posts: n/a
Default

Paul Burridge wrote:
On Sat, 02 Aug 2003 03:25:47 GMT, Active8
wrote:

In article [email protected], lid
says...
Paul Burridge wrote:
Hi chaps,

Can anyone suggest a suitable material from which to make an
ultra-flexible mobile whip antenna say about 3 to 4 feet long. I
need something that can be bent to 90 degrees at a very small
radius and still return to reasonable straightness.

I think thin piano wire will give the best results. Place a lot of
them in a flexible tube to gain some thickness and have them
silvered for conductivity - or add a stranded copper wire.

Spring metal strip may also work, especially if you can manage some
type of hinge at the base that allows it to turn when sideways
force is exerted, or if the force is in one plane.


Thomas


what is a tight bend? music wire comes in diff sizes and the number
in the tube and how tightly the tube conforms to it will have an
effect on the flexibility.


Yeah, sorry chaps, I should have better defined what I meant by 'very
small radius'. I compete in radio-controlled model battles, so the
model stands to get fipped upside down from time to time in a very
bruising environment and it already has a very low ground-clearance,
so using a spring as a base mounting won't help much, I'm afraid.
We're talking about radiuses of as little as 5mm! How about the
specific grade of stainless steel in wire form that springs are made
from? I know where I can get hold of some of that....
"I believe history will be kind to me, since I intend
to write it." - Winston Churchill


The alloy is Type 301 (17% chromium, 7% nickel stainless steel) hard drawn
wire, or even better is a 17/7PH (precipitation hardening) grade that our
firm once produced for tank aerials, that also may take a few knocks.

Both (especially the PH grade) need a final heat-treatment (420C for a few
minutes IIRC) for ultimate spring properties, but to get such a tight bend
you'd need quite a thin wire. It's a matter of the proof strain or limit of
proportionality, how much the outer skin can stretch without taking a
permanent set, compared to the neutral central axis, on the bend.



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Old August 2nd 03, 05:24 PM
Allodoxaphobia
 
Posts: n/a
Default

On Sat, 02 Aug 2003 11:11:31 +0100, Paul Burridge hath writ:
Paul Burridge wrote:

Can anyone suggest a suitable material from which to make an
ultra-flexible mobile whip antenna say about 3 to 4 feet long. I need
something that can be bent to 90 degrees at a very small radius and
still return to reasonable straightness.


Yeah, sorry chaps, I should have better defined what I meant by 'very
small radius'. I compete in radio-controlled model battles, so the
model stands to get fipped upside down from time to time in a very
bruising environment and it already has a very low ground-clearance,
so using a spring as a base mounting won't help much, I'm afraid.
We're talking about radiuses of as little as 5mm! How about the
specific grade of stainless steel in wire form that springs are made
from? I know where I can get hold of some of that....


You might try a section from a steel tape measure.
(Just don't select one of the cheap, Made-In-China plastic/mylar
ones. HI!HI!)
Additionally, try to mount the antenna in a "well" on the robot.
Even a well of 5-10 mm will help out.

HTH,
Jonesy
--
| Marvin L Jones | jonz | W3DHJ | OS/2
| Gunnison, Colorado | @ | Jonesy | linux __
| 7,703' -- 2,345m | config.com | DM68mn SK


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