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Old 28th Feb 2019, 7:52 am   #21
Argus25
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Default Re: Magloop Antenna Using ebay LNA

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Originally Posted by G0HZU_JMR View Post
However, I think your loop antenna is equivalent to a scaled up H field probe. i.e. similar to the classic near field probes used for EMC work.
I agree with that, it is exactly what it is.
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Old 28th Feb 2019, 3:21 pm   #22
Bazz4CQJ
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Default Re: Magloop Antenna Using ebay LNA

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Originally Posted by G0HZU_JMR View Post

However, I think your loop antenna is equivalent to a scaled up H field probe. i.e. similar to the classic near field probes used for EMC work. I have a suite of these here.
I had not thought of using one of those LNA's on a magloop (even my un-refined intuition was unsure about that) until I stumbled upon the webpage where they were doing exactly that. Since the initial results were so poor, I've not done anything further with it, but I did obtain a "Wellgood" pcb from George Smart and some 3866's kindly supplied by Graham and so I have the Wellgood about half built now, and I'm hoping that will perform to the same standards as its forebears.

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Old 28th Feb 2019, 4:27 pm   #23
G0HZU_JMR
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Default Re: Magloop Antenna Using ebay LNA

Yes, the INA02186 MMIC is a very scary part. As I think I mentioned on your other thread this MMIC will have two stages and the two stages share the common ground legs of the '86 plastic package. I'd actually argue that this is a tad reckless by the manufacturer when they put this MMIC inside the 86 plastic package with its long ground legs. I think this MMIC is better to use in the '70 package as the INA-02170. It will tolerate a tiny bit more inductance in the PCB grounding before going unstable.

To use the INA02186 on a PCB I think you are supposed to use a very thin PCB material and lots of chunky via holes. It obviously must be possible to get it to test out as unconditionally stable when fitted to a well designed PCB but there will be virtually no margin for error. At a ballpark estimate I think the overall ground inductance would need to be <0.1nH per leg. This can realistically only be achieved with a skinny PCB and lots of fat via holes.
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