David,

It would be simpler to swith to an antenna that provides a DC path, than to
build an RF driven detector.

Tam/WB2TT
"David Huisman" wrote in message
...
I am unable to use DC continuity. Even if I had a termination at the
antenna
base , this would only indicate broken cable, but not a cut antenna. The
DC
path would need to be to the tip of the antenna.

I have some 10-bit analog inputs available for monitoring and can resolve
down to a couple of mV.

Any other ideas ?

Thanks

--

Kind Regards

David Huisman "Tarmo Tammaru" wrote in message
...
David,

If your antenna has DC continuity, put DC on the feedline through an RF
choke and resistor. Do it like this: DC voltage to resistor to RF choke
to
center conductor of coax. Red LED from junction of resistor and RF choke
to
shield of coax. The red LED will come on when the path is broken. If the
antenna normally does not provide a path, connect anothe RF choke at the
antenna, in such a way that whoever steals the antenna also takes the RF
choke. You want the RF chokes to be PARALLEL resonant somewhere just
above
the operating frequency.

Tam/WB2TT
"David Huisman" wrote in message
...
Hi,

I am looking for some ideas for a low cost circuit to detect if an
antenna
has been broken or removed
from a 10mW transmitter.

Initial thoughts are to measure SWR but I need a small, low cost
circuit
I
can place between PCB Antenna connector and the antenna.

Thanks in advance for any assistance

Kind Regards

David Huisman