Reflectivity of metals at UHF frequency band

[vns]

I have an antenna radiating at a frequency in the UHF band (300MHz - 3GHz). I am interested in the effects of reflectivity of different metals (aluminum, copper, steel), and they all seem to behave in the same way although they have different conductivity. Is this an effect of frequency? Why?

 

[chuckey]

I would guess its that all metals have such a high conductivity with respect to free space. Try a really poor conductor, err, 40 swg nichrome (old fire element).
Frank

 

[FvM]

The term reflectivity suggests that are you asking for the behaviour of metal sheets or plates. Although resistivity and surface roughness changes the behaviour to certain extent, you'll most likely see "full reflection" even for metals with higher resistivity, e.g. said NiCr alloy. The resistivity matters more if you are building high Q cavity resonators, waveguides or antenna elements form different metals.

Frequency plays a role in combination with skin effect and surface roughness.

 

[Darktrax]

Even if the surface resistance is worse than most metals, for example, carbon fibre, RF reflection seems to be nearly total.

The wavelength matters also. It is possible to use chicken-wire, or wire mesh without any loss of gain if the gaps in the wire are less than 1/10 of a wavelength.

Think also of frequency selective surfaces used for sub-reflectors with dish antennas. An array of little crosses, resonant at X-Band, on a material transparent to S-band signals, gives less than 0.1dB loss through the surface, and less than 0.1dB loss on the X-Band reflection.

I doubt there would be any significant difference between various metals used as reflective surfaces.