Combining 4 fm/tv Antenas into one,what is all needed,and how much does it coasts?

[Turok]

Hello!

3 days ago,i read a intresting report,from a man in germany,that connected to tv antennas,together into one,that he can receive 200 km away from austrian boarder orf over dvb t,all antennas,must be the same type, in a distance of around 5-6 meter between each antenna
2 antenna same type on the underside ,with distance 6 meter,and the same,on the up side also!

now i only want to try this here only with fm antenna,because dvb signal here,only for orf in dvb t no use for on my location!

what is all for electronic parts needed,to connect 4 fm antennas into one,each antenna,when i do everything right,i know in the meantime,bring you aproximently 5 db more signal,but i need now component parts,what all is nesarsary,for this big project!

maybe the installtion of 8 identicly antenna 4 on v polarisation and 4 on horzontal,whould be the best!

but how it can happen,that there are no iritation signals,when all 4 antennas work together?

did someone ever try this?
thanks,for your input!

 

[Channel Hopper]

It's called an array, and for FM (or DA it should be far easier than with UHF antennas as you will be working no higher than Band III.

The only real necessity is to get the individual cables at the same length in order to combine the signals, some cancelling out occurs otherwise.
The individual antennas should be about two metres apart and all of them at roughly the same distance to the transmitted source (again for positive phasing)

I would not try to combine both polarities to start off with, you might have reasonable success with two dual arrays and two separate incoming cables.

At VHF frequencies, you should find any reasonable RF splitter can be used.

 

[Turok]

Hello!
thanks for your reply!
if i would install 8 fm antennas ,4 for each polarity,i would use to sepearate cables for sure
how about the signal lost,of thoose kind of rf spliters i should use?
will the not take,the gain win ,oif this antennas away,iam not sure today,is it realy posible,to find all the nesarsary components,in good quality,but i want to try,step by step!

 

[Channel Hopper]

Average loss on a four way combiner at VHF frequency is less than 6dB, so an addition of three more antennas means you are losing the gain of one.

What does improve though (similar to installing a larger parabola in microwaves) is a tighter beamwidth of the overall system, so the noise caused by off beam signals is also reduced. This is where you can start adjusting the distances between the four antennas to alter the beam collection (useful if the transmitter is out of site or you have a mountain nearby).

 

[Turok]

yes here its only beam collection,from the maintain,signal on many weak channels from a large distance here much better,then in areas without mauntains and no reflections,of signal!

 

[PaulR]

Years ago, when I used to partake of VHF amateur radio contests, we used arrays for both 2m and 70cm. 2m is equivalent to 145 MHz, half way between FM and DAB. so will be relevant to both.

Have a look at this page for a discussion of spacing of bayed antennas and of matching the antennas together - including a power splitter (which is what we used to use if memory serves me well).

_http://www.grantronics.com.au/docs/StkYagis.pdf

 

[Turok]

Hello Paul!
thanks for the great link,is very intresting to read!
around one week ago,when i was zapping channels on astra,in the evening,i watch the last secounds of a report on zdf infokanal,where the talk about a gigantic new seti@home project somewhere in the desert,where the try to combining,the surface of many many hundrets big eart station dish,into one gigantic surface,to catch all signals from the universe!
before i was thinking,that the combining,of satellite dishes surface,to improve the signal,for our tv use ,is not posible,but this report say it that it works!
i dont know how,i also forgot the name of this pdoject,google would knows more,but i dont know how it was called,so i cannot give more information about it,maybe someone knows more?