Can a monopole antenna detect a 1 microwatt signal? The signal strength is 1 microwatt. If so how?

 

You need to look at the total system of the antenna (as a transducer of propagating EM signals/RF waves in a medium), transmission line (antenna feed of those captured signals from the antenna) and detector (as part of a receiver using the signals from the transmission line antenna feed)



Your question, as asked, is completely vague. Yes, No, Maybe ...

 

Could it detect a 1 nanowatt signal or would that be too small?

 

Could it detect a 1 nanowatt signal or would that be too small?

Same response ... Yes, No, Maybe ...

 

Could you extract information from a 1 microwatt radio signal, such as video, audio or text, using a monopole antenna?

 

In radio normally the term detect is performed in the receiver. I can answer that by rewording the question a little.
Yes, a monopole when it is tuned to resonance, impedance matched and connected to a receiver having the required sensitivity.

Look for the receiver's sensitivity specifications. I have seen specs showing receiver sensitivity of 1uV.
A quality receiver does not need much help. Not all receivers are capable of sufficient gain and filtering. Where does the gain come from?
A low noise pre-amplifier (LNA) that will cover the frequency band can improve the signal strength. 18-32 dB, that gain is strong,
The added signal might be to overcome the loss of a notch filter for example removing industrial noise like 240 Hertz.
A monopole antenna for example can have a specified gain like 14 dB. So the location, the receiver, the pre-amp, the antenna and the ground
combined will improve the reception sensitivity.

 

How do i build a receiver that has the required sensitivity?

 

How do i build a receiver that has the required sensitivity?

You can:

1. Buy one
2. Look for a receiver kit
3. Look for a schematic diagram with a bill of material published in a hobby magazine.

 

So it is possible to build a receiver with a sensitivity of 1 microvolt?

 

So it is possible to build a receiver with a sensitivity of 1 microvolt?

Easily today with modern technology. The Deep Space Network is receiving signals in the range of a fraction of a femtowatt. DSN's 34-meter antennas can detect signals as weak as -160 dBm. That's like 2.2e-9 into a 50 ohm load.

For things like regular FM radio receivers a common specification is the IHF Sensitivity.
https://www.rfcafe.com/references/p...uner-specs-popular-electronics-march-1973.htm

 

Can you build a receiver with a sensitivity of 1 nanowatt at home?

 

Can you build a receiver with a sensitivity of 1 nanowatt at home?

Sure you could.
https://forum.allaboutcircuits.com/threads/interesting-chip-to-create-an-am-sw-fm-radio.129261/

 

Sure you could.

I have used that part and it is good to 2uV on FM. Not 1nW.

 

Can a monopole antenna detect a 1 microwatt signal?

Where did this number come from?

Could it detect a 1 nanowatt signal or would that be too small?

This is 1/1000 of the power. Where did this number come from?

So it is possible to build a receiver with a sensitivity of 1 microvolt?

yes

Can you build a receiver with a sensitivity of 1 nanowatt at home?

no

 

An important point: µW and nW are not units of signal strength.

Signal strength is measured in V or dB. Watts are used to specify the output of a source but received signal strength is a matter of the E-Field (electric field, one half of the electro-magnetic radiation).

So, really the concern is field strength close to the antenna of the receiver. This is measured as volts per unit distance, specifically V/m. or dBµV/m (dB relative to 1µ/m).

This may seem pedantic but when analyzing cases like this it is important to make these distinctions since you can’t even ask a well formed question without the proper terminology.

 

I have used that part and it is good to 2uV on FM. Not 1nW.

I know, it's just a example for the OP as a simple receiver type. Still it's unlikely the OP will build anything. Good GPS chips today (using pseudonoise codes to detect signals below the noise level) are much better than that FM receiver chip.
https://natronics.github.io/blag/2014/gps-prn/
https://www.everythingrf.com/community/understanding-gnss-sensitivity

Acquisition sensitivity represents the minimum power level at which a GNSS receiver can achieve a position fix. This is the minimum level to successfully perform TTFF under cold start. Cold Start is the TTFF condition where the GNSS receiver has no information about the satellites above. It needs to conduct a full search of the sky to find the satellites in view and obtain the almanac and ephermal data. Acquisition sensitivity is usually around -140 to -150 dBm.

 

Picture from post #10. Look at the line STERO and the line MONO. If you reduce the bandwidth of the signal to 'old telephone' then there would be a line that much below. Every time you reduce the bandwidth you can detect a weaker signal. You must transmit slower. Morse code is sent very slow and can have a very limited bandwidth.

Because we don't know what you want to receive, we are just guessing. We don't know what frequency. Some have background noise and some not so much.

 

The best naval class receivers demanding no any surplus crygenic cooling of input semiconductors are able, typically to sense about 0.1 microvolt. Thus applying the guess that any antenna have impedance of 50 Ohms applicate the Ohms Law and get N=V^2/R=(1E-6)^2/50=2.0E-10 W or 0.2 nanowatts.

 

crygenic cooling of input semiconductors

What is the budget for this project? LOL

 

What is the budget for this project? LOL

I think he means (judging from previous conversations with the poster), one's that don't require cryogenic cooling.

And there's no need. Today you can buy a room temp, sub 1.0 noise figure LNA. That's a equivalent noise temp of only a few tens of K, so you'd need Helium cryogenic cooling to be much better.
Room Temp LNA
https://lownoisefactory.com/product/lnf-lnr1_15b_sv/

Cryogenic LNA
https://lownoisefactory.com/product/lnf-lnc6_9a/

For a few grand I could rig a old cryogenic (12K) vacuum pumping system head, He compressor and facilities.