Been having an interesting discussion about filtering for VHF and UHF when using the HackRF as a transmitter. Which got me thinking, how hard can it be. Well I now know why VHF and up filters have the copper pours pulled back and everything stitched to the bottom side ground plane. The strays on this are killing me. Its certainly usable, but its rubbish. Boards that work quite fine at HF are almost totally unusable at VHF. There is something new i can incorporate into future designs to improve things more generally. Better design is better design yeah?
I made up a duplex for my arrow antenna over 10 yrs ago and used all SMD for everything, can only handle 10-15w but I only use with handheld.
If you are looking at using the boards for V/UHF you’ll need to take the tracks into account for inductance.
Hope all is going well your wave Rob. Cheers Adam
Hows things Adam, all well here. Yeah this was just a throw together to see what would happen more than something I wanted. I took a couple of pF out of each node and now its at least on frequency, but the stop band is being very affected by the strays still.
HF is so forgiving LOL