Microwave loss in gaseous materials
Microwave loss in gaseous materials
(OP)
Has anyone experience in measuring the rf pathloss in any readily available gas, such as SF6, Helium, ? etc.
I have a thought about using it as microwave absorber and am wondering if someone out there has some info. It would be good to find a few gases with varying losses.
Thanks,
kch
I have a thought about using it as microwave absorber and am wondering if someone out there has some info. It would be good to find a few gases with varying losses.
Thanks,
kch





RE: Microwave loss in gaseous materials
RE: Microwave loss in gaseous materials
RE: Microwave loss in gaseous materials
What I'd hope to find is a very lossy gas. i.e. 5 dB per inch loss at 1 Ghz type numbers.
Water might be a good idea, but I need it ultra light.
I want to fill a balloon with a gas and test it in a waveguide for loss.
Maybe another forum could provide some info, lets see what happens here first though.
I've searched the internet for a few hours and written to gas suppliers with no luck so far.
I'd prefer if the gas is somewhat friendly if it escapes. Although that probably means it's not very lossy.
kch
RE: Microwave loss in gaseous materials
Nitrogen N2 78.08%
Oxygen O2 20.95%
*Water H2O 0 to 4%
Argon Ar 0.93%
*Carbon Dioxide CO2 0.0360%
Neon Ne 0.0018%
Helium He 0.0005%
*Methane CH4 0.00017%
Hydrogen H2 0.00005%
*Nitrous Oxide N2O 0.00003%
*Ozone
+Freon?
RE: Microwave loss in gaseous materials
My instinct on this is "not a hope in hell". It would either have to be conductive or lossy as a dielectric. It would have to have such a high density that it would be liquid at best. Remember that waveguide impedance is around 300 ohms.
You stand more chance at mmwave because the guide would be longer in terms of half-wavelengths.
RE: Microwave loss in gaseous materials
A mist/spray of water vapor has been used with some success, but it requires substantial distances, 10-30 feet.
Thanks,
kch