Re: Return Loss Measurement System

I will use VCO from Synergy. They have a wider tuning range VCOs. But for switches, I think Analog Devices is a better choice. ADI has high isolation non-reflective switches which seems a plus in my design. And for the directional coupler, I am sticking with minicricuits.com, as their DCs are wideband, good for my resonators having switching frequencies.

It will be difficult to tune the VCO to an "exact" frequency, or to know the actual frequency, without using a PLL. Free running, the change in tuning sensitivy (MHz/V) across the band and manufacturing tolerances and temperature drift will cause trouble. But if your measurement system doesn't need to know the frequency value, and just tune to a resonance minimum/maximum and compare different resonators at that unknow frequency, then you might be OK without PLL.

A very nice suggestion and comment. I will start to try to use the setup without PLL and see. If I need accurate results, I might need PLL. Let me give it a try first.

I was about to order components today, and while browsing parts websites, I saw this component.

Just want to have you comments, can I use this one? It is a dual power detector. And, it is easily available in Korea too.

Analog devices take 12 weeks to deliver components.

Shall I order this one?

http://cds.linear.com/docs/en/datasheet/5583fa.pdf

AD's circuit has its own directional coupler even the characteristics of the coupler is not so good.You can surely use this RMS detector with a good coupler even there are other better dual RMS detectors with a better linearity.But this is also fine..In this project, the coupler's flatness, directivity,and load-source matching parameters are important.
And you can measure magnitude only with this set-up.
You're right because AD claimed that the volume production will start on December.

One more problem with AD is, the minimum quantity to buy a component is 1500. I don't want so many power detectors of same model. In Korea, we can buy one piece component easily and use it. That was also one of the reason for me to switch from AD to LT for RF Power Detectors.