Hey,

I am building a robot for a competition (simple drag race on a dirt
road during a canadian winter).

I wanted to use a beacon transmitting in the RF range, and use a
directional antenna to correct the angle that the robot is travelling.
The robot would then travel forward towards the beacon (placed at the
end gate). So far I have no antenna experiance (havent taken the
antenna class yet).

Would a circular antenna work for this project? where can i learn more
about circular antennas?

Also are there any commercial (inexpensive, the competition only allows
a $100 budget), tranceivers I could use (preferably in the 433 Mhz
band). Since i only need a small signal to correct the course, it
doesnt have to be too powerful.

Thank you for your help,

G_dir

On 22 Sep 2006 11:09:52 -0700, "G_dir" wrote:


Thank you for your help,

Hi OM,

Skip antennas and transmitters and use a light beam, or several.

73's
Richard Clark, KB7QHC

The light beam idea is different but it does bring complications
For drag race you haven't got time to focus a light upon a small object
that is moving
Fior this purpose it would seem that a small verticle would suffice
such that the vehicle responds immediatly to commands I assume that as
a drag race range power is not a requirement. Richard was your aproach
based on a guided path control by light rays such that contact would
provide a direction correcting command?
Art

Richard Clark wrote:
On 22 Sep 2006 11:09:52 -0700, "G_dir" wrote:


Thank you for your help,

Hi OM,

Skip antennas and transmitters and use a light beam, or several.

73's
Richard Clark, KB7QHC

On 22 Sep 2006 12:25:42 -0700, "art" wrote:

The light beam idea is different but it does bring complications
For drag race you haven't got time to focus a light upon a small object
that is moving

Hi art,

If time is of the essence, it is of the essence for all applications
equally.

Fior this purpose it would seem that a small verticle would suffice
such that the vehicle responds immediatly to commands I assume that as
a drag race range power is not a requirement.

A vertical has no way to discriminate falling out of a path. UNLESS:

The aeronautical system of holding a flight path is with (or was with)
VOR. It's been a long time since I've maintained navigational
equipment, so my terminology may be way off. However, the concept is
there are two transmitters sending an Morse N and a Morse A, such that
if you are on the flight path, you obtain a constant carrier (the dits
and dahs overlap through carefully balanced antenna arrangement at the
transmitter).

If you should diverge from the flight path, there is an imbalance in
signal and one code predominates over the other. For the race car,
the burden would be on translating which code dominates, and what
course correction would be necessary.

Richard was your aproach
based on a guided path control by light rays such that contact would
provide a direction correcting command?

A light path can be resolved with hardware logic instead of software.
Faster performance.

73's
Richard Clark, KB7QHC

Richard Clark wrote:
On 22 Sep 2006 12:25:42 -0700, "art" wrote:

The light beam idea is different but it does bring complications
For drag race you haven't got time to focus a light upon a small object
that is moving

Hi art,

If time is of the essence, it is of the essence for all applications
equally.

Fior this purpose it would seem that a small verticle would suffice
such that the vehicle responds immediatly to commands I assume that as
a drag race range power is not a requirement.

A vertical has no way to discriminate falling out of a path. UNLESS:

The aeronautical system of holding a flight path is with (or was with)
VOR. It's been a long time since I've maintained navigational
equipment, so my terminology may be way off. However, the concept is
there are two transmitters sending an Morse N and a Morse A, such that
if you are on the flight path, you obtain a constant carrier (the dits
and dahs overlap through carefully balanced antenna arrangement at the
transmitter).

Yes I am aware of that but not for a flight path but for a destination
point
As a Londoner during the war, the big one that is. civilians were
constanly aware
that light emmissions allowed for night bombing but even when we got
rid of glass windows and replaced it with tar paper the dock area was
repeatedly pounded. Fortunately a bomber crashed somewhat intact and
the secret was opened. The germans had two widely separate transmitting
stations one with a continuos dot and another with a continuous dash
and where both transmissions was aimed at a required venue thus the
german bombers mnew when they were over the target when the dots and
dashes merged into a single drone. In relaliation british fighters were
able to anticape their arrival and finally drove them out from the
skies. My family house was knocked out in the early days when it was
like a carpet bombing but as time went on the raids became more
scattered and without the normal prewarningThe germans did not know
that their secret was broken so the British put out a rumour that their
pilots ate lots and lots of carrots which had ingredients that improved
night vision thus the german fighters obtained this addiction to
carrots. Unfortunately the battle continued later with the doodle bug
that I counted as they went over and then a short period of V2s
that fairly quickly stopped as the Allies advanced in France and
Belgium. Sort of something like the Yagi invention which was not
followed up by the Japanese military
because of inter secrecy of the invention between the services. On the
other side of the coin tho the british invented the jet engine it was
the germans who took advantage of it first with the jet fighter but
internal wrangling delayed its inaugeration. It all goes to show that
people reject change even tho it is inevitable and thus account for the
present resistance to the yagi being inefficient because most feel that
is the cat's wiskers and it takes a generation for change to take place
Art






If you should diverge from the flight path, there is an imbalance in
signal and one code predominates over the other. For the race car,
the burden would be on translating which code dominates, and what
course correction would be necessary.

Richard was your aproach
based on a guided path control by light rays such that contact would
provide a direction correcting command?

A light path can be resolved with hardware logic instead of software.
Faster performance.

73's
Richard Clark, KB7QHC