Signal Splitting?

Discuss commercial and home made antennas.
Username
Posts: 462
Joined: Sun Oct 09, 2016 7:27 am

Signal Splitting?

Post by Username » Tue Aug 06, 2019 3:18 pm

Hi
I have a VHF Antenna and will use them for different Amateur Radio thinks. I need to add Multiple SDR so I have to splitt the Signal.
I have some stuff at home who is not ideal. :(
Are there any commercial with a SMA or N Plug with multiple outputs?
Thanks

snn47
Posts: 166
Joined: Tue Dec 27, 2016 11:00 pm

Re: Signal Splitting?

Post by snn47 » Sat Aug 10, 2019 10:28 am

Every splitter will attenuate the signal strength coming from your antenna somewhat. The more ports you want the higher the attenuation so you need to add a preamp to compensate the losses.
Search for splitter combiner and you'll find versions with e.g N or SMA connectors.

Username
Posts: 462
Joined: Sun Oct 09, 2016 7:27 am

Re: Signal Splitting?

Post by Username » Sat Aug 10, 2019 10:31 am

What are the Main producer of that?

HighSNR
Posts: 43
Joined: Mon Sep 18, 2017 8:14 am

Re: Signal Splitting?

Post by HighSNR » Sat Aug 10, 2019 11:35 am

Considering a 2 way splitter firstly. When you split a signal, the best case is that half the power goes to each output. That's a 3dB reduction.

An important characteristic of splitters is maintaining the characteristic impedance of the transmission line (normally 50ohms). To achieve this of the the maximum bandwidth and in a small size, this is often done with a resistor network. Resistive splitters cause an extra 3dB loss, so for this type you have a 6dB total power reduction from the input port to the output port. You can make a DIY restrictive splitter fairly easily. Just google restrictive splitter.

The more ways you split the signal the more loss you have at each port.

For receive only systems you can often mitigate this spltting loss by placing a low noise amplifier(LNA) to boost the signal before it is split.

If you want something a little more fancy you can look for a Wilkinson divider. These only have 3dB loss, but have a more limited bandwidth and require more expensive construction techniques.

Username
Posts: 462
Joined: Sun Oct 09, 2016 7:27 am

Re: Signal Splitting?

Post by Username » Sat Aug 10, 2019 12:30 pm

I need for VHF some Ports for the Multiple Band for example for the Weather Sat and so on.

snn47
Posts: 166
Joined: Tue Dec 27, 2016 11:00 pm

Re: Signal Splitting?

Post by snn47 » Sat Aug 10, 2019 7:15 pm

As always, if you ask for advice you should explain what you need/want to do. We do not have a crystal ball to find out what you want. This is for you to decide and tell us before anyone can give you an advise. Similiar if you say I need transportaion is a motorcycle or a car sufficient, dou you need a truckor a bus to allow you to transport what you want ;) . It is similar for RF devices, there are many different options how to achieve distriution of signals from a single source to multiple outputs. To give you an idea:

-How many ports 2, 4 or more do you want?

-How broadband/which freqncy band do you want to use the Divider/Combiner/Splitter for?

-Which coax connector type (e.g. C, N, SMA, SMB, SMC)?

-WHich impedance 50, 60 75 Ohm?

-DC-pass through or not?

-Are you willing to built it yourself, or want to buy it?

The cheapest Divider/Combiner/Splitter that does not maintain the impedance asr T-coax connectors, they are just the inner conductor to all three ports

Crude resistive devises are made/sold for CATV/SAT-TV use like RCA T56476 4 Way Signal Splitter Coaxial Cable which are broadband.

Than there are other option like a rat race or splitter which have a limited bandwidth

Directional coupler provide a low attenuation through path (>0.5 dB) and have one or more pickups each 10 or more dB attenuated, while the feed through attenuation is >0.5 dB, which are broadband.

If you start searching you can easily find manufacterer names and their distributors e.g. minicircuits.com, mcli.com

Username
Posts: 462
Joined: Sun Oct 09, 2016 7:27 am

Re: Signal Splitting?

Post by Username » Sat Aug 17, 2019 3:59 pm

-How many ports 2, 4 or more do you want?
depend on the Freq, Band, Channels.
For Amateur VHF lets say 4.
-How broadband/which freqncy band do you want to use the Divider/Combiner/Splitter for?
VHF and some for UHF.
-Which coax connector type (e.g. C, N, SMA, SMB, SMC)?
In: N, Out: SMA
-WHich impedance 50, 60 75 Ohm?
I guess the use 50Ohm
-DC-pass through or not?
nope the LNA powered via USB
-Are you willing to built it yourself, or want to buy it?
Buy

I need a Company who shipp from Europe so I dont have to pay the huge import fees.

radiolistener
Posts: 47
Joined: Thu Jan 25, 2018 10:48 pm

Re: Signal Splitting?

Post by radiolistener » Mon Aug 19, 2019 8:28 am

Username wrote:
Sat Aug 17, 2019 3:59 pm
For Amateur VHF lets say 4.
it's better to use antenna switch, something like this https://www.mfjenterprises.com/Product. ... =MFJ-1704N

Because splitter add loss and you will get worse signal on the output of splitter.

Antenna switch allows you to connect antenna to selected device with no need to reconnect connectors. Since it uses just single output port connected to antenna, it has very small loss.

Username
Posts: 462
Joined: Sun Oct 09, 2016 7:27 am

Re: Signal Splitting?

Post by Username » Mon Aug 19, 2019 9:09 am

:? How could I connect 4 SDR to one Antenna with?!

radiolistener
Posts: 47
Joined: Thu Jan 25, 2018 10:48 pm

Re: Signal Splitting?

Post by radiolistener » Mon Aug 19, 2019 10:49 am

just connect your antenna to antenna switch input and all your sdr receivers to antenna switch outputs. Then just switch antenna to selected sdr receiver which you're want to use.

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