Re: Inverted U terminated low noise antenna


David Cutter
 


Hi Chris
 
Could you post a pic of your set up for this measurement, I'd like to test some chokes and I think jig layout is very important to avoid capacitive pick up. 

----- Original Message -----
Sent: Saturday, March 11, 2017 8:25 PM
Subject: Re: [CrossCountryWireless] Inverted U terminated low noise antenna

I've found a graph relating choking impedance to common mode attenuation in a presentation ChokeCurrentBalun.pdf by Jacques Audet, VE2AZX.

In this graph 10 dB of attenuation equates to 100 ohms, 20 dB 1000 ohms and 40 dB 10000 ohms.

A figure of 5000 ohms is 33 dB.

The 9:1 current balun common mode rejection figure up to 30 MHz is >40 dB so this would give a figure of >10000 ohms.

The attenuation at 50 MHz is 32 dB, this would give a figure of 2500 ohms.

Regards,

Chris

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