Making tuneable length monopole to maximise cantenna waveguide function:
As can be seen in photo below, I have purchased a threaded copper sleeve (sold as brass coupling nuts) and a threaded copper rod – turning the rod allows its length to be varied. I have used one of my previous hydrogen line cantennas to define the “ideal” length of the probe within the can and this threaded rod allows that length to be varied +/- 5mm from that length. I am also able to replace the rod with shorter or longer one if needed, without making another probe from scratch.
Brass coupling nuts:
Chassis N-type connectors:
Calculating cantenna dimensions for the LRO stove pipe cantenna:
Hence, if I place the centre of the monopole probe 92mm from the back of the can, then it will allow me to tune this distance by moving the back from 92-102mm. I have a press-fit cap for the back of the can which will allow tuning of this distance by 10mm.
Press-fit cap for stove pipe that allows distance from back of can to N-type chassis connector to be tuned:
