conductive filament for printing the waveguide for microwaves (low power microwaves)  

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That is an interesting thought. I am assuming you are at fairly low power or just receiving signals.

Alternatively could you print the part with just PLA and either line the insides with a thin copper of aluminium foil?  Else paint it with a conductive paint.

I would suspect conductive filament would still have a fairly high resistivity (OK if you at doing absorbing cones for an anechoic chamber though). I'll look it up and chime in here if I find something interesting that might work.

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Thank you very much for pick-up the topic 🙂

Up to little extend, I was considering the conductive paint as a finish of job, but... from start of my thinking:
1. I'm able to design a dish with f/D ratio and diameter as I wish and I'm on way with design a dish to print and assemble it... so painting the final product is absolutely to do (I have a plan to use the PLA or PETG, so final surface painting for this propose should be enough)
2. The waveguide as a "cantenna" (very easy to calculate and made) as a 'lighter' of dish; I think about receiving and transmitting the signals but with power up to few Watts; now I'm after some tests on 23 & 13cm band and I'm sure that kind of antenna is working; 3D printing give me a precision as much as I cannot achieve in other methods; also I'm free with dimensions

For this (2) I'm looking for the conductive filament and it would be very nice to read some of you suggestion. Thank you in advance for your time 🙂

I know nothing about wave guides but have you considered the high resistance (several K) of conductive filament.

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Yes, I considered it. You have a right that kOhm of filament resistance is not good but to have a "proof of concept" is enough. From my side it's job for learn and test - of course, finally I'll go to some metal workshop do to is in metal 🙁 Anyway I'm interesting in designing, printing and use the setup for radio amateur contact with other hobbyists and first early prototypes are promising, but I'm looking for better filament....

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In this moment I can say that part of my topic is to close, because I finished printing the 13cm can antenna using the conductive filament. Antenna is working very well, SWR is more that acceptable 🙂 Of course still could be open the thread with many doubts about durability, strength, ability to transmit a power, final efficiency, etc.  but in this place it's separate topic.

Now, still I need your help and suggestion about conductive filaments because this one (Print-Me Ampere) is very hard to print OR I have not enough experience to do it. Small object are printable, but larger ... not 🙁 I waste lot of filament and I had a clogging the extruder few times, so...

If somebody have some more experience with conductive filaments it would be very nice to exchange the knowledge, to not overload forum I think we can do it by private conversation.

All the best for everybody

final information

Just now, I can say that this topic is for close. I have a two antennas for 2,3 i 3,4 GHz with very good results of transmitting and receiving of signals. I'm sure that all of my theory imagination is to do in real world 🙂

RE: conductive filament for printing the waveguide for microwaves (low power microwaves)

@piotr

I'd be interested to know if it could fry a subwoofer in a passing car. 🤣 fingers X