Electronics > RF, Microwave, Ham Radio

Experimenting with waveguides using the LiteVNA

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joeqsmith:
Still looking for a better coupler to replace the old Narda part I have been using to measure S11.  The Narda 3095 looks like it would be a good fit.  Cheap, covers the X-band and good directivity.   These use the APC7.  There are some <$15 USD from China.  Searching this site, someone had asked about them a few years ago but I don't see any data.  They advertise them good for 6GHz.  Wonder how they perform at double that frequency. 

https://www.eevblog.com/forum/testgear/apc7-to-sma-adapter-from-china-ok/


Cheap APC-7 SMA adapters from China.
https://www.ebay.com/itm/314581375697

Datasheet for couplers
https://nardamiteq.com/product-spec/097-Couplers.pdf

3096, directivity 25dB
https://www.ebay.com/itm/304867686545

3095, directivity 33dB 
https://www.ebay.com/itm/304898554282

coppercone2:
Wow you can sinter with a extruder printer?

I am guessing its a high copper content 3d print wire that is then baked in a kiln for burn out and sintering?

I am just waiting for my ground cable to come in for the tig lol, got the wrong gas lens in my kit so I only have the quartz one.

I think usually they say that out side of the frequency band of operation for the next octave you might be able to find a stable narrow region of operation that is potenitally usable in spite of the 'modeing' that occurs. But I have no idea for the band under. I think its potentially usable at a higher frequency for some small random bandwidth, but not with the lower end.. that is a hard cut off I think? Wavelenght too small for wave guide = odd transmission modes, wavelenght too big for wave guide =? (I think its very high reflection but not sure)

from what I understand : the most out of bounds components you have (operating past their max frequency) the less likely you can find a useful transmission band, since each component might have a random area that transmits some frequency but they are not correlated so with more then 1 component you might not have a path through.

joeqsmith:
I would say we tried to sinter with an extruder printer.   Yes, as you described.

All of the parts for that extender are fine for the X band now, except that coupler.  Even at 11GHz, it works better than I would expect but this is really the problem.   The mixer's IF is limited to 4GHz but right now, I can't even sweep up that high.   

https://www.eevblog.com/forum/rf-microwave/experimenting-with-waveguides-using-the-litevna/msg4850513/#msg4850513 

Thinking I may add in that terminated SPDT relay as well so we don't have to move cables.   Eventually, it needs to get mounted into a box but for now I'll leave it as a 3D mess. 

joeqsmith:
Try finding couplers with over 25 dB directivity.   They are not common.  I want to keep the coupling at 10dB and plan to give up the half dB loss by leaving it in-circuit.   HP offered the 33311B relay with a 5V option.  It seems like it would be a good fit.   

https://www.ebay.com/itm/144419029196

coppercone2:
here is a 50db coupler
https://www.everythingrf.com/products/waveguide-couplers/flann-microwave/228-248-16133

hidden behind a quote wall.

it appears they are quite long for higher directivity

A 779D or similar is like 30dB.

https://www.romtekonline.com/product-details/multihole-directional-coupler.html
35

might be worth checking the Flann brand out on ebay, they seem to be all that shows up for higher db directivity

https://flann.com/wp-content/uploads/2015/09/Flann-Final-2015-for-Website-Use-06082015.pdf


your finger sir
https://www.ebay.com/itm/175741081773

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