10 - 20 MHz? Ouch! I've got directional couplers that are 'effective' as low as 100 MHz - amd as most of my work in the past has dealt with this range I've been okay. I've got some on-going work (a filter) in the range of .5 to 5 MHz right now. I am able to measure S21 (Insertion Loss) using a spectrum analyzer and signal generator, but shortly I've got to measure S11 (Return Loss or 'VSWR') as well. I'm going to use a crude 'bridge' in combination with a dual-trace scope or a Vector Voltmeter to accomplish this in a round-about fashion (measure complex Z and then compute the Return Loss/S11). http://www.dallas.net/~jvpoll/tech/ph_mag.html Jim ----- Original Message ----- From: "Brendan Moran" To: Sent: Monday, July 08, 2002 2:03 PM Subject: Re: [EE]: Directional couplers & T/R test sets > Thanks Bill & Jim > I guess I assumed that I had something that might work, but when I tried to > find info on using directional couplers, I pretty much came up blank. So, > how does a directional coupler for low RF (10-20MHz) actually work? > > --Brendan > -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.