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RF communication through steel

RF communication through steel

RF communication through steel

(OP)
Hi.

I have a question concerning RF signal amplitude.  What is the effect on the range of RF communication after the signals pass through steel walls?  Approximately how much power is need to pass through these steel walls and have the signal travel about 300 feet?  

My project involves wireless communication between 2 devices, each of which is on opposite sides of an airplane (outside).  So the signal essentially has to pass through the plane.

Any feedback would be appreciated.

-Jim

RE: RF communication through steel

Most airplanes are made of aluminum, not steel. Based on past experience, I'm sure you be back with addditional information to correct my misunderstanding of what you have written...

The signal does not have to pass directly through the direct straight line. Diffraction and reflections will occur around the object blocking the Line Of Sight path. This diffraction can be modelled using GTD/UTD (Google those terms) - but it gets complicated.

If the frequency is sufficiently low, the RF wouldn't even 'notice' the 'small' object.

RE: RF communication through steel

WOW! Do you really mean through steel? (a steel aeroplane!!) The basic answer will be very low/zero range, but frequency details are needed to give possible power figures.
Why will the signal not pass around the fuselage? Unless your aeroplane fuselage is a solid cylinder or unmanned such as a UAV, some of the signal will pass through any windows or cockpit canopy (think using a mobile phone inside a car - sufficient signal goes through the windows to reach the base station)

 

RE: RF communication through steel

Cell phones work perfectly fine on airplanes as well.

TTFN



RE: RF communication through steel

Does your "airplane" have a leaky antenna coupler connecting the inside of the pressure vessel with the outside of the pressure vessel?  If it does, it may be designed for cell phone bands or a specific range of frequency.  These are also used inside train tunnels, so you get much better performance than theory would show without the leaky antenna.

RE: RF communication through steel

(OP)
Thanks for the responses.  It sounds like the signal from device 1 would eventually reach device 2, albeit with some diffraction.

I am interested in the time of flight of the signal.  If there is signifigant diffraction, this will distort this measurement.

I am not sure what frequency we will be using, but from everything I've read it seems that lower is better.  I'd say a good guess is that we'd use something in the 30 MHz range.

That said, if time of flight is my main concern I guess it makes more sense to have enough devices where at least one line of sight connection is possible.

Does this make sense?

RE: RF communication through steel

Multiple devices have their own problems too.

RE: RF communication through steel

TOF for 400 ft --> 3.7 ns

30 MHz --> 33 ns period

TTFN



RE: RF communication through steel

According to a tv documentary I just watched some of the early supersonic aircraft were made of stainless steel because they got too hot to use aluminium.

RE: RF communication through steel

"TOF for 400 ft --> 3.7 ns"

Hmmm... ...am I missing something?

RE: RF communication through steel

sorry, should have been 37.5 ns.

TTFN



RE: RF communication through steel

"400 feet divided by 299792458 meters per second in nanoseconds"

Precanned Google Calculator link:
  http://tinyurl.com/9zyl4

406.681345 nanoseconds

RE: RF communication through steel

me bad

TTFN



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