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Author Topic: Aerial Combiner  (Read 7774 times)

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bratters

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Aerial Combiner
« on: March 20, 2010, 09:13:18 AM »
The RF Systems SP-3 two way antenna combiner has caught my eye and I wonder if anyone has used one of these to feed a single box from 2 aerials?

Although advertised for use with scanners it presumably works OK for RB.

Not cheap but if it works, I would like to give it a go so any advice welcome.

http://www.rf-systems.nl/pdf/sp3.pdf

tarbat

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Re: Aerial Combiner
« Reply #1 on: March 20, 2010, 09:19:32 AM »
What's the price?  And is the SP3 better than the SP1?  It's something I've often considered trying out, with an antenna at each end of my house.

Cumulus

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Re: Aerial Combiner
« Reply #2 on: March 20, 2010, 09:35:51 AM »
I can recommend both the RF1200 & RF1273 from SSE

http://www.ssejim.co.uk/25-coaxialcable&accessoriesfor1090sj.htm

Also worth taking a look at the 1090SJ mk2 antenna polar diagrams.

Cheers,

Peter
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tarbat

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Re: Aerial Combiner
« Reply #3 on: March 20, 2010, 09:38:34 AM »
Thanks Peter.  Might give one of those a try.

btclarke

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Re: Aerial Combiner
« Reply #4 on: March 20, 2010, 09:48:32 AM »
I've been advised by Jim that a combiner for RB signals will not work...
My brother who is an engineer in Radar Systems advises similarly...

Cumulus

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Re: Aerial Combiner
« Reply #5 on: March 20, 2010, 09:58:51 AM »
I've been advised by Jim that a combiner for RB signals will not work...
My brother who is an engineer in Radar Systems advises similarly...


Apologies, I misread the first post, these will not work as combiners but will work well as a splitter, two receivers from one antenna.

All my attempts at combining two antennas, yagi and omni, have failed.

Cheers,

Peter



Jeremy

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Re: Aerial Combiner
« Reply #6 on: March 20, 2010, 10:56:34 AM »
If you run a multi coliniear omni array it will have probably as much gain as your yagi and you do not need both.
There was a very good design somewhere on the forum a few weeks ago for a DIY multi stack.
J.
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bratters

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Re: Aerial Combiner
« Reply #7 on: March 20, 2010, 11:01:54 AM »
I've been advised by Jim that a combiner for RB signals will not work...
My brother who is an engineer in Radar Systems advises similarly...


Hmm. Thanks for that. At £80 a pop it's always better to to ask first!!

Looks like there is an opportunity for someone to come up with something to overcome the single direction problem that so many of us have.

tarbat

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Re: Aerial Combiner
« Reply #8 on: March 20, 2010, 11:03:24 AM »
So, is the conclusion that it's not worth trying to locate two ModeS antenna in different locations, and feeding these into a Radarbox using one of these splitter/combiners?

I'm just trying to fill some gaps in my coverage.  If I put my RB antenna at one end of the loft, I get coverage in areas that I can't get with the antenna located at the other end of the loft.  If I could combine two antenna located at each end of the loft and combine the signals, that would fill in the gaps.

bratters

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Re: Aerial Combiner
« Reply #9 on: March 20, 2010, 11:20:30 AM »
So, is the conclusion that it's not worth trying to locate two ModeS antenna in different locations, and feeding these into a Radarbox using one of these splitter/combiners?

I'm just trying to fill some gaps in my coverage.  If I put my RB antenna at one end of the loft, I get coverage in areas that I can't get with the antenna located at the other end of the loft.  If I could combine two antenna located at each end of the loft and combine the signals, that would fill in the gaps.

Your position exactly mirrors mine Tarbat. I suppose the sheer volume of signals from the two aerials would overwhelm any efforts to integrate them.

Another option would be a switcher allowing only one aerial to be operating at a time, however as everything is loft-based, this would need to be radio controlled to have any pracctical use.


fil

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Re: Aerial Combiner
« Reply #10 on: March 20, 2010, 11:43:16 AM »
What could work for the omni + yagi or 2 omni circumstance is a 2 way rf relay that was toggled at a 1Hz 50:50 duty cycle. The only thing that would be a concern would be the life of the the relay mechanicals. Could be worth a look. A simple car indicator flasher (loaded with a bulb or 2) could be used to provide the switched power to the 2way antenna switch.

CoastGuardJon

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Re: Aerial Combiner
« Reply #11 on: March 20, 2010, 12:20:41 PM »
Hi all, and ingenious suggestion there from fil.   As I understand it, using several antennas and a switching system would work.     But if you try to combine the signals from more than one antenna, the phasing of the signals from the  different sources, albeit only a few feet apart, would be thrown out and either negate each other or act as an echo.     I did buy a very high quality ex Govt./ military quality phasing harness from Haydon Comms, who advertise in Radio User, fitted with N-connectors, but still haven't had time to get around to having a play with it.    Still using the bog standard (but self water-proofed) antenna outside on the roof very successfully, the SSE 1090 and Watson Radar Extender antennas sitting in their boxes, waiting for me to make up feeder leads from RG213 (the Westflex 103 is so stiff) and attach them to the roof.
ANRB :  AOR AR8000 : Icom R-7000 : Icom IC-R9000 : JRC NRD-545 : OptoElectronics Digital Scout and OptoLinx Interface; Realistic Pro-2005 : UBC 800XLT - listed in alphabetical order, not cost, preference, performance or entertainment value!

fil

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Re: Aerial Combiner
« Reply #12 on: March 20, 2010, 12:22:00 PM »
There are a lot of suitable RF relays for this project listed on ebay.

Like this one, http://cgi.ebay.com.au/Matrix-Ultra-Fast-Microwave-MUX-SMA-RF-relay-switch_W0QQitemZ280479946434QQ
Its a 12 to 1 RF mux relay, so you could switch a maximum of 12 antennas into one radarbox! 12 maybe an overkill but still this relay would be ideal for constant switching of 2 or more antennas.

fil

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Re: Aerial Combiner
« Reply #13 on: March 20, 2010, 12:41:56 PM »
A solid-state alternative to the relay would be a pin diode RF switch, like this one...
http://cgi.ebay.com.au/Murata-Hi-Speed-switch-1296-MHz-transverter-eval-New_W0QQitemZ380215090485QQ
It is the type of technology that is used in 2 antenna diversity systems (802.11abg and the like). This type of switch is ultra fast and low loss, however they are prone to damage from ESD and the driver circuit is more complex.

CoastGuardJon

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Re: Aerial Combiner
« Reply #14 on: March 20, 2010, 12:51:09 PM »
Fil, thanks for those, good looking items.
ANRB :  AOR AR8000 : Icom R-7000 : Icom IC-R9000 : JRC NRD-545 : OptoElectronics Digital Scout and OptoLinx Interface; Realistic Pro-2005 : UBC 800XLT - listed in alphabetical order, not cost, preference, performance or entertainment value!