Could anyone tell me what determines what voltage and amps a antenna will pick up from a radio frequicy. Is there a formula. I'd like to know because I'm thinking of building a rectenna and I'm having a hard time either finding the information I need or understanding what I do find. Thanks

 

It depends on two principles. The density and the orientation of the radio frequencies. The density part is determined by the emitted power and the distance from the emitter. The FCC has legal formulas for estimating this field strength.

And then there is the receiving antenna polarization. If this polarization is not matched......one can have a weak signal, even though the density is strong.

 

This might help -

http://www.smcelectronics.com/DOWNLOADS/1974-ARRLANT.PDF


Regards, Dana.

 

Could anyone tell me what determines what voltage and amps a antenna will pick up from a radio frequicy. Is there a formula. I'd like to know because I'm thinking of building a rectenna and I'm having a hard time either finding the information I need or understanding what I do find. Thanks

There is no unique solution to the problem. It starts with the received power level, often expressed in dBm. dBm is an abbreviation for "dB with respect to a milliwatt". A typical received power level available at an antenna that is far away from the source, 10 wavelengths for example, is -110 dBm. At this point we can state that there are an infinite number of solutions where we multiply a voltage by a current and we get a power level. The power level in question is 11 orders of magnitude smaller than 1 milliwatt. About 10 femtowatts. So this power level might produce, in an ideal world with 100% efficiency, 10 microvolts at 10 nanoamperes, or 100 microvolts at 1 nanoampere. Can you see the problem?

 

This looks challenging -

http://eceweb1.rutgers.edu/~orfanidi/ewa/ch16.pdf


Regards, Dana.

 

Chapter 24 should also be interesting.
BTW EW&A by Orfanidis is a great book.