Using Si5153 to calibrate antenna (impedance measurement)

[electr0dave]

Hello.

I'm with some doubts.

I want to build a device to measure the impedance of an antenna (arround 14MHz).

The antenna should have an impedance of 50R.

I can connect the output of the SI5153 to an antenna?
If the antenna has an impedânica of 50R (resistive), 5.6mA is enough?
The impedance of the antenna can vary from 30R to 75R.

I wanted to do a very simple equipment, to be able to calibrate simple antennas HF.


Thanks for your help.

 

[FvM]

What is Si5153?

 

[electr0dave]

Re: Using Si5351 to calibrate antenna (impedance measurement)

Sorry, my mistake .

It is actually a si5351.

I've been watching too many references ...

 

[FvM]

Mean Si5351? It's only a clock generator, essential function for measurement of generally complex antenna impedance is vectorial voltmeter. Or use impedance bridge is a simple method.

 

[electr0dave]

Hello.


The idea would be to use Si5351 to generate the frequency to the antenna. After measuring with an impedance bridge.

But the IC has a very low power output ... I'm afraid it's not enough.

What do you think?

 

[FvM]

Problem is also that the bridge requires sine rather than square wave input. A filter (e.g. low-pass) is required. Could insert an amplifier too.

 

[electr0dave]

But the IC has a maximum output of 5.6mA.
How can he have a 50R output impedance?

I'm not quite understand how it works ...

 

[FvM]

But the IC has a maximum output of 5.6mA.

No. 5.6 mA is a supply current specification.

Although the device is said to have 50 ohm output impedance, it's probably not designed to be operated with 50 ohm resistive load.

As previously mentioned, it's no good idea to drive an impedance bridge with a square wave.

 

[electr0dave]

You know a sine wave generator with similar characteristics to this integrated circuit?