Tried to measure voltage and current at the antenna.

i tried to measure the voltage going into the antenna and the current going into the antenna with a digital multimeter. i set the multimeter to 200 millivolts and sometimes i got a reading of zero volts. i used a spectrum analyser and i still saw spikes appear on the screen of the spectrum analyser. so i got a reading of zero volts and spikes appeared on the screen of the spectrum analyser, strongly indicating the antenna was radiating radio waves. so i got a reading of zero volts and the antenna is still radiating radio waves. sometimes i get a voltage reading of 100 microvolts and i see spikes on the spectrum analyser. so i get a reading of 100 microvolts and the antenna is still radiating radio waves.

this is a schematic of the circuit i am using. so the current flows out of the pin 3 of the crystal oscillator module and into the black prong and then out of the red prong and into the antenna. i am using a crystal oscillator module that has 4 pins and i tried to find a symbol for a crystal oscillator module that has 4 pins and show all the connections. the output of pin 3 is presumably a square wave with a frequency of 100 megahertz. the antenna is connected to pin 3. so does this mean i am getting false readings? does this mean the voltage is sometimes too small to measure? does this mean the multimeter cannot measure the output because the bandwidth of the multimeter is too small?

the antenna is a jumper wire used to connect electronic components on a breadboard.

i tried to measure the voltage going into the antenna and the current going into the antenna with a digital multimeter.

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Not possible. multimeter frequency range is a few kHz maximum. Vector network analyzer or RF impedance bridge are possible tools to measure antenna impedance.

Impedance of simple wire antennas can be well estimated from literature formulas.

so it is not possible to measure the voltage output of pin 3 with a mutimeter?

dl09 said:

so it is not possible to measure the voltage output of pin 3 with a mutimeter?

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Dear forum-mate, you have no knowledge about RF and Signals.
Please train yourself on them and then try to do something.

BigBoss said:

Dear forum-mate, you have no knowledge about RF and Signals.
Please train yourself on them and then try to do something.

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can you answer the question is it possible to measure of the output of pin 3 with a multimeter?

dl09 said:

can you answer the question is it possible to measure of the output of pin 3 with a multimeter?

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My answer, no way..
Multi-meters ( top models ) can measure voltages and current up to 1MHz, no more.
Multi-meter Probes, connections etc. are NOT appropriate at all for RF measurements.
RF and Microwaves are specialized eras and their measurement techniques are very particular.
In order to learn RF and Microwaves, the sequence : Read,Read,Read,Simulate,Implement,Debug,Read,Simulate so on..
I'm an RF Engineer with 40 years experiences and I still don't know something concretely..

if i buy a 50 ohm coaxial cable that is 15 feet long and cut off some length until it is 2.46 feet long, will it still be 50 ohms?

Yes, the length does't affect the impedance of a coaxial cable.

if i use nec7 software can i accurately calculate the impedance of a the jumper wire i use as an antenna?

As long as you can model the environment, capacitance, losses, etc
yes. But this case of what you are doing does not make sense.

A good reference work is ARRL Radio Amatuer handbook to learn RF
basics.



Regards, Dana.

i appreciate the help a lot.