[HELP] How to covert high frequency to DC?

[sassyboy]

Hi to all. I was travelling on the bus to work this morning and thought of an interesting project. How would one converts a wireless signal say at 5 GHz to DC? The wireless signal can be captured via a good gain directive antenna for maximum signal strength. Since I am pretty much out-of-date with today's available electronic components. Would there be a device I could buy to plug my antenna signal to the input of this imainging-device for a DC output? This imaginary-device will need to be able to detect a very small signal and I am talking about 60 micro volt.

Furthermore, in normal situation the wireless signal may not always be available. How would one store the weak signal being detected and use it for output when necessary.

Please shred me some idea. Immensely grateful!

 

[FANT]

The RF signal is usually too weak to allow a convenient use rectifying it and storing in a battery or a capacitor.
Infact the RFID buttons work up to some meters from the transmitter, if you intend to use to collect energy you have to stay very close to the transmitting antenna.

Mandi

 

[sassyboy]

Supposing the transmitter is very near and sending a strong signal. What would I need? A rectifier? Adder?

 

[jallem]

you are trying to do is known as peak detector. It is just
a rectifier for high frequency(Narda has one). It follows the
peak of the rf signal, consequently its output is a DC rectified
signal. You did not say what is your intention. I remember
there were some intent years ago to "send" energy using RF.
Those intents all failed since the efficiency of it is too low.

 

[sassyboy]

Thank you all. Very interesting.

I have had a brief search for the Peak Detector Jellem has suggested. The Narda offers **broken link removed** which no need for external power. While some others like those offered by Linear Technology requires external power. Nevertheless, I wonder what is the lowest RF signal strength detectable by a peak detector these days. Once I know this, I can draw by attention into developing a very efficient antenna receiver covering a wide frequency range.

 

[jallem]

Hi Sassyboy,
I did not do a search this time for Linear Technology "detector"
but I remember that some of that I searched were based on
opamp and consecuently very low frequency for my application.
The detector is just a mere diode. You can boost the output using
opamps but the frequency would be limited to about 1GHz(in the
best case). So if the detector is going to be used for energy trap
you are going to find yourself giving more energy to the opamp
than the energy you are going to collect from the air.

 

[startboy]

my dear:

you could try detect circuit by receive, like envelope detect by

ASK...ect, than you could adding a filter to rejection noise, last, you

need to add some amplifier to gain your weak signal, but your amplifier

bandwidth need to control by your needed, then you could extend rejection

noise by your amplifier.


c.c.huang