#1470

[@aduedc]

Normally , I like your clips, but this one was a little convoluted. To explain RF couplers you could start with: A segment of transmission line with matched load and source. Now we bring a "wire" in parallel with transmission line and we detect a signal. This signal depends on how close these two "wires" or transmission lines are together, the length of our probe, the strength of signal on the main line. Now, if the load is mismatched with line , say it is open instead of matched load, the RF signal gets reflected at the load. Now if we connect both side of our probe wire to two detectors, such as spectrum analyzer, we will see forward going wave creates a forward going signal in our probe which can be detected by one detector, and return wave creates a reverse going signal in the other end of our probe that can be detected by other detector. Now, since we are interested only on return wave, we replace the detector that detects forward going wave with matched load. This is Now called a directional coupler.

[@mariofilippi3539]

Couplers have always been confusing to me when used as return loss bridges. You video on the basics of how they are used makes sense. Tnx es 73's.

[@hubercats]

Very nice presentation. Thank you!

[@Mark-hb5zf]

The Merrimac coupler likely uses 2 transformers wired to form a coupler since it goes down to 10MHz and being in a small package. The 'thru line' is a 1 turn primary (i.e. a single wire going thru the cores), whereas the the number of secondary turns determines coupling. The directivity is due to currents cancelling and voltages adding. Sounds complicated, but if drawn out - it's very simple. Very ingenious tho. Attaching a pad (not terminated into 50 ohms) at the output would be a good example of measuring RL. I.e. a 3dB pad would result in a 6dB return loss (3dB loss thru the pad, and 3dB loss again when reflected).

[@citizenrich]

Wonderful tutorial! I'm curious if its possible to insert a signal through the coupled port? By that I mean you send a signal from OUT to IN and insert an additional signal into CPL.

[@douglasstrother6584]

Microwave components, an HP calculator & scotch on the rocks: looks right to me.

[@BryanTorok]

I actually would like to see one of these opened up to show what is inside that makes the one-way valve work. Then, I'd like to see an explanation of RF circulators, how to use them and how they work. Thanks for the explanations, great content as always.

[@aerofart]

IMSAI, Is it possible that some of that “bleed” signal is in fact reflection through the “reverse path” due to slight impedance mismatch between source and load? And of course, for critical applications, one would also want to characterize this system at the operating frequencies, because unless this coupler is perfectly linear, there would be a difference, correct?

[@herbertsusmann986]

RF magic! Nothing like it.

[@EfieldHfield_377]

Thx you so much for sharing. I have been enjoying your channel. Two questions if you manage to see this and have time for an answer. I have a 20dB, 2GHz coupler I purchased from mini-circuits about two years ago for not much money (less than $100 I think) I used for testing my purchased antennas - I have a few laying around the lab, un-labeled, so it comes it handy - you can never actually physically measure those whip antennas and get what you might expect - if not labeled you must test. Works fine for what I need. My SA is very similar to yours - Siglent sells a return loss bridge for the same SA that fits the input track-gen perfectly but also enables a software feature for about $700. Have you ever used this for qualifying your antennas and if so do you think it is worth it - Im guessing the software makes an automatic measure but thats just a SWAG. Second question, those back thumb wheels for the SMA connectors are they part of your SMA connector or an add on you purchased seperately that fits over the SMA. If purchased seperately do you have an Amazon or DK link. That quick turn action with those thumb wheels is quite nice.

[@IMSAIGuy]

wheels: www.pcbway.com/project/shareproject/SMA_Thumbwheel_Wrench_b3dc35b6.html

[@EfieldHfield_377]

@@IMSAIGuy Thx so much ordering 10 of them

[@mr1enrollment]

you have gone and done it,... now please tell us how the coupling port works,... you started it,.... now no one is gonna let you alone unless you -- lol

[@IMSAIGuy]

be careful what you ask for: kzbin.info/www/bejne/r326oIVuZbWgatk

[@rfburns5601]

You must do an explanation of how these couplers work. Tomorrows episode: #1471 How RF Couplers Work. Ha!