Antenna Resonance Measurement using an Oscilloscope and signal generator, MVI_4378

Quick demonstration showing how an oscilloscope, an RF signal generator and a simple box with 5 resistors (3 - 50R0 and 2 - 1K0) can be used to observe antenna resonant frequency in the 7 MHz range.

Note: This is no substitute for an Agilent VNA, but then, it isn't going to cost as much either if this GPTE (General Purpose Test Equipment e.g. scope, signal gen) are just sitting around idle ...

More info (schematic of resistors in 'magic box', calculation of impedance using values read off O-scope):

http://web.archive.org/web/20070823163053/http://www.dallas.net/~jvpoll/tech/...


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Category:

Science & Technology

Tags:

• Antenna Resonance
• Sweeping an antenna
• Antenna Measurements
• VNA
• 6925
• RigExpert
• Antenna Impedance
• Impedance bridge
• Antenna VSWR

[Neslakim]

The images to the site you have linked up does not work :(

Do you have another site? Or know when they will work again?

[uploadJ]

@Neslakim

I just clicked the link and it worked for me - one might try again later ... I don't think the archive dot org (the 'Wayback Machine' website) site (where the files are) has very robust servers, I have had errors and delays from them on occasion in the in the past ...

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[RussellTuan]

how those resisters were connected inside the magic box?

[uploadJ]

RussellTuan - I have added a link in Description above for that information.

Basically, the three 50 Ohm resistors form a 'bridge' circuit and the two 1K resistors provide isolation so the O-scope does not load the bridge.

Also note the coax cables to the O-scope must be terminated in 50 Ohms (or turn on 50 Term function in menu of scope) and the coax lines *should* be of equal length to CH 1 and CH 2 of O-scope (to make phase on O-scope read properly).

Regards, uploadJ

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[bearing01]

cool video. /John

[RussellTuan]

@uploadJ great ,thanks a lot!!

Regards, Russell Tuan