Trying to build rf impedance bridge.

[dl09]

I am planning to build a rf impedance bridge, to confirm the antenna impedance is 36.5 ohm. Could I use a digital multimeter to accurately measure the ac output of the impedance bridge?

This is a schematic.

 

[KlausST]

Hi,

The answer is already given in your other threads:
No, because a DVM is not suitable for HF measurements.

Klaus

 

[dl09]

I didn't think the answer would be yes. But I can't afford a 100 mhz oscilloscope. Any alternative to accurately measure the ac output of a rf impedance bridge? The frequency is 100 mhz, I don't think it is in the audio tange.

 

[KlausST]

Hi,

No, it's certainly not in the audio range. It's at about a factor of 10,000 away...

And please, if you mean Megahertz, then use "MHz", with a capital "M"
Because a lower case "m" means "milli"
And "Hz" is the unit for frequency...with a capital "H".

Repeatedly I recommend to start with basics.
My interest in electronics started abou4t 30 years ago. First as hobby, then for several years I went to school to go deepein in ekectronics, mathematics, physics. Worked in many areas of electronics, from production, assembling, developing, testing electronics.
HF never was my favourite, but I had to learn HF PCB design and all around EMI, EMC.
But still I call my HF knowledge just "rudimentaty".

What I want to say: Take your time. Start with basics. Again: Start with basics. Do courses. Random ideas don't result in progress.
Don't expect to be finished with learning within a couple of months. For sure - if you focus on HF - it won't take 30 years...
I'm still learning, that's why I'm a member of this forum.

Klaus

 

[danadakk]

An Inexpensive Impedance Bridge, July 1944 QST

Here is an amazingly detailed article on how to construct and operate a near-lab-quality impedance bridge out of relatively

www.rfcafe.com

http://www.nutsvolts.com/magazine/article/a_low_cost_rf_impedance_analyzer

Leader LDM-815 Transistor Dipmeter & LIM-870 Antenna Impedance Meter

RF Bridges

Above some possibilities, back ground material.


Regards, Dana.

 

[dl09]

will a vector network analyzer , accurately measure the voltage and current at an antenna?

 

[danadakk]

Yes, but VNA is generally speaking a low power small signal test instrument.
Basically provides Z and S Parameters of transmission systems, cable, antenna,
load.....

What accuracy are you seeking ? What power levels ? What cost do you want to
budget ?


Regards, Dana.

 

[FvM]

VNA is the preferred tool to measure antenna impedance.