3D turntable idea, input needed.
Posted by
Mike Phillips
on 2007-01-24 11:32:19 UTC
I once had a terrific R & D job making small pcb antennas for laptops,
PDA's, cellphones etc for wireless communication. It was the kind of
work a guy could do until he was 100 years old. One thing I was told
was that customers love having a 3D plot of their antenna's
performance. Most labs only furnish an X and Y plot.
Imagine a plywood box (Anechoic chamber) that has a 10' x 10'
footprint and an 8' ceiling. In that box you have a stepper or servo
driven horizontal turntable about 8" in diameter. The turntable sits
at one end of the box about 30" above the floor. The other end of the
box has a highly directional antenna (horn) pointed at the turntable.
Generally the turntable spins the antenna 360 degrees in about 20-30
seconds. Then the operator lays the antenna on it's side and spins it
around 360 degrees again. I want to make the horizontal turntable tilt
as well. What needs to happen is that the turntable top is tilted
about 10 degrees from horizontal, then the turntable is rotated 360
degrees. Then tilted to 20 degrees and rotated again. All the way up to
nearly 90 degrees of table tilt. The turntable has to have a home
position so it will be rotating back to 0 degrees before rotating the
antenna again.
This process makes a 3D plot of the antenna output. So if there is a
weak direction or weak hemisphere, it can be dealt with in the design
of the antenna.
The biggest trick is that the table and mechanisms driving it have to
be something as reflective as wood. Anything metallic will cause a
reflection in the box that would be picked up and plotted as part of
the antenna. The motors probably have to be down at floor level with
rods reaching up and turning a plastic gearset.
So it would seem that Mach3 would be an easy choice for operating such
a setup. Mach3 would rotate the turntable and turn on the analyzer that
watches what the Horn antenna sees. Mach3 would set the turntable at
the required tilt as well. I think just one of the parallel port pins
going high or low could trigger the analyzer that is attached to the
transmitting antenna to start recording.
So maybe some Gcode to control the tilt and rotation of the turntable
as well as some Mcode to turn on the analyzer?
Ideas? Comments?
Mike
PDA's, cellphones etc for wireless communication. It was the kind of
work a guy could do until he was 100 years old. One thing I was told
was that customers love having a 3D plot of their antenna's
performance. Most labs only furnish an X and Y plot.
Imagine a plywood box (Anechoic chamber) that has a 10' x 10'
footprint and an 8' ceiling. In that box you have a stepper or servo
driven horizontal turntable about 8" in diameter. The turntable sits
at one end of the box about 30" above the floor. The other end of the
box has a highly directional antenna (horn) pointed at the turntable.
Generally the turntable spins the antenna 360 degrees in about 20-30
seconds. Then the operator lays the antenna on it's side and spins it
around 360 degrees again. I want to make the horizontal turntable tilt
as well. What needs to happen is that the turntable top is tilted
about 10 degrees from horizontal, then the turntable is rotated 360
degrees. Then tilted to 20 degrees and rotated again. All the way up to
nearly 90 degrees of table tilt. The turntable has to have a home
position so it will be rotating back to 0 degrees before rotating the
antenna again.
This process makes a 3D plot of the antenna output. So if there is a
weak direction or weak hemisphere, it can be dealt with in the design
of the antenna.
The biggest trick is that the table and mechanisms driving it have to
be something as reflective as wood. Anything metallic will cause a
reflection in the box that would be picked up and plotted as part of
the antenna. The motors probably have to be down at floor level with
rods reaching up and turning a plastic gearset.
So it would seem that Mach3 would be an easy choice for operating such
a setup. Mach3 would rotate the turntable and turn on the analyzer that
watches what the Horn antenna sees. Mach3 would set the turntable at
the required tilt as well. I think just one of the parallel port pins
going high or low could trigger the analyzer that is attached to the
transmitting antenna to start recording.
So maybe some Gcode to control the tilt and rotation of the turntable
as well as some Mcode to turn on the analyzer?
Ideas? Comments?
Mike