I would like to use a battery power feed interconnect as the antenna for a portable 433MHz project. I would assume that an inductor is required at each end of the 173mm interconnect with an AC coupling capacitor to the RF output but would appreciate some advice from others with more experience.
Ideally I'd like to have some idea of the expected performance relative to a quarter-wave wire antenna and how the component choice may affect the antenna resonant frequency.
It's an interesting idea. What have you tried so far?
That will work fine, assuming that the inductors and coupling capacitor are chosen correctly.
The antenna will work best if it is vertical and perpendicular to a ground plane, which seems unlikely for a power feed.
I suggest an end fed halfwave, aka "j-pole", if it is possible to "inline" it with DC continuity. That is a unique problem. One strange un-mentioned aspect, the feed is two wire, the antenna is a one wire. So you have to isolate both wires.
I just completed a similar project, but for the high frequency bands. Search for the term "bias-t". I have a remote antenna tuner for a vertical antenna. The tuner is powered by 12 volts from my ham station. The 12 volts and RF is fed into one bias-t in the house, through coax cable to the bias-t in the remote tuner. Capacitors pass the RF and stop the DC. RF chokes stop the RF and pass the DC. Works.
By the right choice of components, it could work for 433mHz, also.
Good luck
Paul
Yes, another example is powered preamplifiers, very common in GPS antennas. Also a bias-t on the GPS module and one in the antenna module.
Strictly speaking, the bias-t only provides RF/DC isolation, so it's only half of the solution. The other half is isolating a section of the power supply line, so it can be fed with the RF signal component.
What I'm saying, it's easy to feed RF back through the supply line with a bias-t. But then you have to "break it out" with another bias-t and connect it to a resonant radiator of some sort. If you insist that it be the supply line, you do have a puzzling (but intriguing!) design problem.
At the "break out" bias-t, you need both a radiator and an RF counterpoise, or you have to somehow provide a balun to convert the unbalanced bias-t output to a balanced antenna such as a dipole, that doesn't require any counterpoise.