RF Splitters & Combiners - How do they work?
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- Опубліковано 3 січ 2025
- This video explains how a Hybrid RF Splitter / Combiner works. The main purpose of this device is to split or combine an RF signal while providing high isolation between ports and good impedance matching to 50 ohms. This design is commonly used with LDMOS and other high powered amplifiers. The splitter can take a single signal source and use it to drive 2 or more RF boards while the combiner can take the signal from 2 or more RF boards and combine their power output. This video also shows how to make insertion loss, isolation, and SWR measurements using a NanoVNA.
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Wow. Great walk thru. Answered questions I had on auto transformers and using coax in a transformer. Subscribed and will be going over you other videos. Very well done!
Thanks for you positive feedback!
Great walk-thru and description!
Thanks!
73...
Excellent dissertation!
When testing the splitter at the end of the video, shouldn't the other port be terminated into 50 ohms?
Would you upload more videos about RF? İ am learning it from you and they are excellent
Superb...
Hi RF Man, I love RF and you have some very interesting stuffs. I like your contents. Just subscribed. ECErcuit.
great content again!
GREAT INFO 😀
One thing you should have mentioned is the phase angle between the ports, 0 or 180 degrees. I will leave that with you to mention. Nice video. Good for those out there learning RF engineering. Also should have placed a 50 ohm load on the second port, as you measuring the power output of the splitter. (Balance)
73's
In your last example with the RF amplifier, does it cause any problems leaving the second output unterminated? Where is that other 1.5W being dissipated? In the 100 ohm resistor?
Yes, if you leave the output unterminated, the power will dissipate across the resistor. I wasn't concerned with only 1.5 watts. It is good practice to terminate both sides. Regards
Thank you!
Excellent, what kind of the 100ohm resistor you put on it, and what is the wattage?
Typically a thick film metal oxide resistor is use. Wattage should be 50 to 100 watts depending on you application. Current only follow through the resistor when outputs are not balanced.
That's super helpful! Thanks! I'd love the specific construction details of your little splitter- IE: what kind of cores for the transformers and what you used for the resistors. I've been wanting to make a splitter for a few receive-only applications that I want to run from the same antenna, and whipping up something like this would be ideal. I could probably wing it, but the more details the better. Thanks so much for the video.
I mention most of this in the video. I'm using material 43 for the cores, RG316 for the 50 ohm coax, and a 100 ohm (2xZo) 3 watt isolation resistor. It is wired as shown in the schematic. Compensation capacitors (22pF) may be needed depending on the construction. I hope this helps. Regards, RF Man
Realizé un "hybrid splitter" similar con núcleo binocular y cables corrientes.Necesité añadir condensadores en al salida de 25 ohms, pero funciona perfectamente.Supongo que es por falta de la capacidad del cable rg-316.
También el combinador funciona de maravilla.
Video útil y muy bien explicado.
73 's
Amazing video, thank you very much! I guess that in the last experiment, the "other" 1,5w gets dissipated in the resistor?
With a 50 ohm load, the second port would also have 1.5 watts on the output.
nicely done
Too bad this channel has gone dark would have liked to have seen more content like this.
I am working on more content and will be posting soon.....
@@carminecampo2045 Cool, thanks for the update.
Great vide explanation! Is there any device, or conjuntion of devices, that would allow me to have several receivers from a common antenna, but if any of the devices transmits, all the other devices should be isolated ? Don't know if I made the question clear, but happy to give more details in PM if needed. Thanks in advance
What would be the advantage of this splitter vs standard Wilkinson divider with transmission lines changed to coaxials. Resistor is needed as well this circuit has longer cables (wilkinson only lambda/4 length). Thank you interesting topic covered
T2 is not used to transform impedance because you have already two 50 ohms ports in parallel that give you 25 ohms! It's use for balancing between port.
I learned something. I did not know you could use coax for the winding. I thought that all windings needed to be next to each other, but with a coax the center windings run inside the shield windings.
Most high powered splitter combiners used with LDMOS amplifiers used coax. This is the primary application.
Can a combiner be used to combine the signals from two closely spaced antennae to present a stronger signal to the Low Noise Amplifier/RF Front-End?
Another great video!. I always enjoy and learn alot from your videos.
Quick question: The 2:1 auto transformer, the way I am looking at it might be wrong but I see it as a 4:3 turn transformer with an impedance ratio of 1.78. Is that correct? Thanks 785
Very nice, but where is the input and the input ground? Further: Very good and interesting.
The grounds are shown on the schematic. The female SMA connectors are all grounded using the coax shield. Regards
Trying to understand the effect of using coax , is it true that the inner conductor will see the magnetic field going thru the core? The shield -only shields- the inner conductor from electric field?
I'm not sure I fully understand your question. Let me answer it this way. If you have a ferrite core and wrap one turn of 50 ohm coax around it, the inner conductor and the shield will have the same inductance when each is measured with an inductance meter. The permeability of the ferrite material has the same effect on both the inner and outer conductors.
Very interesting, I've made a similar hybrid combiner for two 100W AM Transmitter power modules, with success, using pairs of FB-43-1020 beads and ECW. So how would a 4 port configuration look like, that is, four 50 ohm input ports combined into a single 50r output port?
Email me and I will send you a schematic. My email address can be found on my website. rflinear-amplifiers.com
Would it be possible to use an N-way Combiner if one coaxial wire has 75 ohms impedance and two other wires have 50 ohms impedance?
Yes, that would be a problem. The impedance transformer would not be correct. You should transform the 75 ohms to 50 ohms first. Regards
So is it possible to run two amplifiers together to make a combined output for example 2 x 1kw amplifier to one coax out
Yes, that what the combiners are used for. Thanks
Hi, do you do custom work? I am looking for a fully built RF amp focused on 470-490 mhz. 3-5 watts. 12-15v dc. Do you have anything like this? Thank you, V
This is a super awesome video!! I will look for this topology when looking at amplifiers and other RF circuits.
I am curious about one thing. If you want the 2 outputs have the same phase shift and amplitude why would you use the center core and shield of coax for the 2 conductors instead of identical lengths of single conductor wires? I would think they would have different surface areas or resistances because they are so different.
You are making turns on a transformer so you want the EM to radiate and not using the shield as a fixed impedance to ground.
What is the difference between winding it with coax or just single conductor wire?
You can also use single conductors and achieve similar results.
Do you have a email that can ask you about some amplifier questions?
Hi What cores do i need for 2 x 1.5 KW Combiner on 1.8 Mhz Mix 61 or mix 43?
for the first Auto-Transformer, Turns Ratio is 1.33 which gives only 1.76, how about using 14 turns : 10 turns, which gives 1.96:1
My question would be this ,on your version would the staking of the two cores cause a fluxation issue and cause a outa ballance of impedence or saturation ...causing a issue ..
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Promo sm 😅
Grt presentation this article is exactly what i am looking for to complete my design for a two antenna space diversity reception system to feed my receiver that has only one antenna input, grt job there 歯ｐ待てtyvm