"Paul Burridge" wrote in message
...
On 2 Aug 2003 16:24:24 GMT, Allodoxaphobia
wrote:

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.

Not sure about the tape measure suggestion, but mounting in a well is
something I'd not considered and am most grateful for the idea of!
Thanks...

Does it have to be a whip antenna? Why not try a horizontal circular loop?
Since you are working line of sight to the robot, the signal loss from going
from vertical to horizontal shouldn't matter much unless your transmitter is
extremely low power. A loop could be mounted inside a wooden or fiberglas
body and be pretty safe from attack.

Is there anything in the rules forbidding your installing a jammer
transmitter to cause the other bot to lose its command channel? Probobly a
poor use of what little electrical capacity the onboard battery holds, but
it would be one way of causing the other bot to freeze in place and become
like a deer in the headlights.
thanks, John.
KC5DWD

On Sat, 2 Aug 2003 18:24:44 -0500, "john graesser"
wrote:

Does it have to be a whip antenna? Why not try a horizontal circular loop?
Since you are working line of sight to the robot, the signal loss from going
from vertical to horizontal shouldn't matter much unless your transmitter is
extremely low power. A loop could be mounted inside a wooden or fiberglas
body and be pretty safe from attack.

If I believed this idea was workable I'd have implemented it by now.
You need to bear in mind that immediately beneath the polycarbonate
surface armor, there's a hulking great metal framework. Consequently,
sandwiching the antenna between the armour and the frame is going to
lead to unacceptable loss of radiated energy, I'd have thought. Unless
anyone knows differently..

Is there anything in the rules forbidding your installing a jammer
transmitter to cause the other bot to lose its command channel? Probobly a
poor use of what little electrical capacity the onboard battery holds,

There's a considerable amount of battery power on board, actually,
since the peak current draw is well over 100 Amps at times. A few
milliwatts for a local jammer would therefore be a negligable drain on
resources. *However* as you've already guessed, jammers are banned, as
are EMP pulse type weapons and such like. The reason for this is very
sound, when you think about it: it makes for really bad TV. The
producers want to see as much *action* as possible. You ain't gonna
get that if everybody's disabled everybody else's robot!
--

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

On Sat, 2 Aug 2003 18:24:44 -0500, "john graesser"
wrote:

Does it have to be a whip antenna? Why not try a horizontal circular loop?
Since you are working line of sight to the robot, the signal loss from going
from vertical to horizontal shouldn't matter much unless your transmitter is
extremely low power. A loop could be mounted inside a wooden or fiberglas
body and be pretty safe from attack.

If I believed this idea was workable I'd have implemented it by now.
You need to bear in mind that immediately beneath the polycarbonate
surface armor, there's a hulking great metal framework. Consequently,
sandwiching the antenna between the armour and the frame is going to
lead to unacceptable loss of radiated energy, I'd have thought. Unless
anyone knows differently..

Is there anything in the rules forbidding your installing a jammer
transmitter to cause the other bot to lose its command channel? Probobly a
poor use of what little electrical capacity the onboard battery holds,

There's a considerable amount of battery power on board, actually,
since the peak current draw is well over 100 Amps at times. A few
milliwatts for a local jammer would therefore be a negligable drain on
resources. *However* as you've already guessed, jammers are banned, as
are EMP pulse type weapons and such like. The reason for this is very
sound, when you think about it: it makes for really bad TV. The
producers want to see as much *action* as possible. You ain't gonna
get that if everybody's disabled everybody else's robot!
--

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

Zak wrote:
Paul Burridge wrote:

Just one point, though: is stainless steel a reasonable radiator of
RF energy?

Stainless steel is awful at conducting electricity - so it won't make
a very efficient antenna. But how much it really matters, I don't
know.

So's my body, but I get a decent TV picture if I touch the aerial input ;-)

Zak wrote:
Paul Burridge wrote:

Just one point, though: is stainless steel a reasonable radiator of
RF energy?

Stainless steel is awful at conducting electricity - so it won't make
a very efficient antenna. But how much it really matters, I don't
know.

So's my body, but I get a decent TV picture if I touch the aerial input ;-)

"Active8" wrote in message
k.net...
In article ,
says...

"Paul Burridge" wrote in message
...
On 2 Aug 2003 16:24:24 GMT, Allodoxaphobia
wrote:

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.

Not sure about the tape measure suggestion, but mounting in a well
is
something I'd not considered and am most grateful for the idea of!
Thanks...

Does it have to be a whip antenna? Why not try a horizontal circular
loop?
Since you are working line of sight to the robot, the signal loss
from going
from vertical to horizontal shouldn't matter much unless your
transmitter is
extremely low power. A loop could be mounted inside a wooden or
fiberglas
body and be pretty safe from attack.

Is there anything in the rules forbidding your installing a jammer
transmitter to cause the other bot to lose its command channel?
Probobly a
poor use of what little electrical capacity the onboard battery
holds, but
it would be one way of causing the other bot to freeze in place and
become
like a deer in the headlights.
thanks, John.
KC5DWD


i always thought jamming would be a great weapon, but i bet it's
illegal. i'd like to see the rules for some of those competitions. i'd
think it would be fun to try sometime. i wan't to smash jay leno's
bot.
come on. "chinkilla"? who writes his lines?

Paul's restricted to two bands, which i think stinks. he's probably
not
allowed to jam. The band restriction i really don't like since it's a
bot competition not a DX contest.

I have a friend who competes. I suggested jamming to him; he said it
was not allowed.

Besides, they're not really robots. All of them are just RC toys. I'll
be more impressed when they are autonomous.

"Active8" wrote in message
k.net...
In article ,
says...

"Paul Burridge" wrote in message
...
On 2 Aug 2003 16:24:24 GMT, Allodoxaphobia
wrote:

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.

Not sure about the tape measure suggestion, but mounting in a well
is
something I'd not considered and am most grateful for the idea of!
Thanks...

Does it have to be a whip antenna? Why not try a horizontal circular
loop?
Since you are working line of sight to the robot, the signal loss
from going
from vertical to horizontal shouldn't matter much unless your
transmitter is
extremely low power. A loop could be mounted inside a wooden or
fiberglas
body and be pretty safe from attack.

Is there anything in the rules forbidding your installing a jammer
transmitter to cause the other bot to lose its command channel?
Probobly a
poor use of what little electrical capacity the onboard battery
holds, but
it would be one way of causing the other bot to freeze in place and
become
like a deer in the headlights.
thanks, John.
KC5DWD


i always thought jamming would be a great weapon, but i bet it's
illegal. i'd like to see the rules for some of those competitions. i'd
think it would be fun to try sometime. i wan't to smash jay leno's
bot.
come on. "chinkilla"? who writes his lines?

Paul's restricted to two bands, which i think stinks. he's probably
not
allowed to jam. The band restriction i really don't like since it's a
bot competition not a DX contest.

I have a friend who competes. I suggested jamming to him; he said it
was not allowed.

Besides, they're not really robots. All of them are just RC toys. I'll
be more impressed when they are autonomous.

On Sun, 3 Aug 2003 11:40:55 -0400, "Bob Lewis \(AA4PB\)"
wrote:

Stainless steel is awful at conducting electricity - so it won't
make a
very efficient antenna.

I doubt that the difference in resistance between stainless and copper
is going to cause any significant additional losses in a whip antenna.
That difference will be small compared to the other losses. Stainless
is often used for whip antennas because of its mechanical properties.

Yes, I've several proprietory s/steel whip antennas that give
excellent results. But a question springs to mind. If a s/steel
antenna has slightly higher resistance, does that appreciably lower
its Q?


--

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

On Sun, 3 Aug 2003 11:40:55 -0400, "Bob Lewis \(AA4PB\)"
wrote:

Stainless steel is awful at conducting electricity - so it won't
make a
very efficient antenna.

I doubt that the difference in resistance between stainless and copper
is going to cause any significant additional losses in a whip antenna.
That difference will be small compared to the other losses. Stainless
is often used for whip antennas because of its mechanical properties.

Yes, I've several proprietory s/steel whip antennas that give
excellent results. But a question springs to mind. If a s/steel
antenna has slightly higher resistance, does that appreciably lower
its Q?


--

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

On Sun, 3 Aug 2003 10:19:55 -0700, "Richard Henry"
wrote:


Besides, they're not really robots. All of them are just RC toys. I'll
be more impressed when they are autonomous.

That's not entirely true these days. Autonomy in certain areas of
control is becoming increasingly prevalent. It'll be interesting to
see how this particular aspect of design develops over the coming
years...
--

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