Uhf- dx antenna

[mouse3]

Hi,
I need your s help to found the best ever UHF antenna for fringe reception.What you know about this antenna,gain and directivity,are there other UHF brand antenna for fringe or this antenna it s the best?
Any help will be appreciated,
mouse.

 

[Channel Hopper]

Stick with a yagi arrangement if you can, easier to stack.

_http://www.ifwtech.co.uk/g3sek/stacking/stacking2.htm

 

[aceb]

That looks like an old CM 4251, widely used by DXers in the States but never seen one this side of the Atlantic, I've not got the spec to hand but ask in the WTFDA forum and someone will know or I expect google will have the answer somewhere. I've used a pair of Antiference XG21s in the past but changed to a four stack of Triax BB grids and that worked very well, I bayed them all to improve directivity while keeping broad vertical acceptance and coupled it with a low noise Gaasfet mast head. The other advantage of the grids is the flat gain response, individually their performance is nothing to shout about but once you start stacking them they are hard to beat. There's nothing to stop you keep going of course, back in the 80s there was even an installation of 16 of them in Southern Ireland to pick up UHF TV from the UK mainland, Aerial Techniques in Poole, Dorset supplied the hardware.

 

[Llew]

_http://www.rocketroberts.com/cm4251/cm4251.htm has some info on that one.

I had an XG21 and preamp on a rotor for many years to check any openings. Sadly the preamp packed up recently, and in dismantling the mast (well, two with a coupler) the old aerial bashed against the roof and knocked off a few directors

 

[mouse3]

I found two intresting picture about array.One it s for moonbouncing,but must work well on terestrial reception and next picture it s from one military mobile equipment.The antenna looks very similar with Swann antenna,the best UHF antenna i tested myself.The gain and directivity it s beyound X element antenna.
16 antenna array work well i think,but maybee you help me with the electric diagram for connections all that 16 antenna to one low noise UHF amplifier.
Thanks.

 

[Channel Hopper]

A phased array requires all antennas to have the nodes supplied to the main download simultaneously.

Easy enough with VHF, but with high UHF band the wavelength is under 35cms.
To ensure the maximum signal all antennas should be fitted exactly perpendicular to the grid, parallel to each other, and all collectors on the same plane.
All cables from each collector should run to exactly the same length to the combiner, and if there is more than one combiner (say five lots of four) then each cable between them should also be the same length, to within 0.5cms.

Don't forget, gain is only one part of phasing, beamwidth is also narrowed on yagis, and the directionability/stability of the stack becomes almost as important, very much like a large dish.

 

[mouse3]

Thanks for advice Channel Hopper.

 

[mouse3]

Guys,i need again Your s experience and knowlege abot UHF antennas.
I want to test helix UHF antennas for fringe in my area particular for Slovak Tv digital channels,but i found nothing on internet about UHF antenna diagram,only for VHF and radioamator band.
I m intrested in special for channel 64 UHF-818 MHz Vertical,this frecvency it s used by Slovak tv station.It s away from my location but i have mountains where to go and make the test,i need only electric diagram to make the antenna at home.
Thank You,
mouse.

 

[Channel Hopper]

Do you mean helical antennas ?

_http://www.antenna-theory.com/antennas/travelling/helix.php

 

[mouse3]

Yes Channel Hopper,helical antennas.
I found samthing on internet for advertise only,no electric diagram to replicate at home,it s from Canada,number of turns 24, 23 dB gain,470-880MHz.Wade high gain helical antennas.

The helical are more easy to replicate,and the gain it s good for that construction simplicity.
What do You think,what perform better,one helical UHF antenna array made by 16 UHF helical antenna or one 5m UHF parabolic dish make at home from mesh ? Above 5m the construction become more complicated and heavy,i dont know if one parabolic it s enough.
I m a little confused about this two options,i dont know what it s the best for UHF fringe reception.

 

[mouse3]

[QUOTE..., back in the 80s there was even an installation of 16 of them in Southern Ireland to pick up UHF TV from the UK mainland, Aerial Techniques in Poole, Dorset supplied the hardware.[/QUOTE


Maybee You have one photo with that antenna array.
I found samthing on internet but i cant download,hundred of UHF antennas array on top of the hills,i dont know for what purpose,but looks amazing.I dont know about the cost,but looks to be the DX-ers heaven.

 

[Channel Hopper]

What do You think,what perform better,one helical UHF antenna array made by 16 UHF helical antenna or one 5m UHF parabolic dish make at home from mesh ? Above 5m the construction become more complicated and heavy,i dont know if one parabolic it s enough.
I m a little confused about this two options,i dont know what it s the best for UHF fringe reception.

Without knowing what you might need in terms of gain, and at high UHF its a difficult call.

I would however opt for the parabolic, as you can find the odd Hero 5m antenna that has come to the end of it's C-band life for peanuts, and go from there.

 

[Terryl]

Yes Channel Hopper,helical antennas.
I found samthing on internet for advertise only,no electric diagram to replicate at home,it s from Canada,number of turns 24, 23 dB gain,470-880MHz.Wade high gain helical antennas.

The helical are more easy to replicate,and the gain it s good for that construction simplicity.
What do You think,what perform better,one helical UHF antenna array made by 16 UHF helical antenna or one 5m UHF parabolic dish make at home from mesh ? Above 5m the construction become more complicated and heavy,i dont know if one parabolic it s enough.
I m a little confused about this two options,i dont know what it s the best for UHF fringe reception.

As 90% of the TV signals (that I know of) are horizontally polarized it would be best to use an antenna array that is horizontally polarized, a helical antenna will work but an antenna at the right polarization will work even better.

If all your looking for is a UHF antenna with good gain and directionality, then Google for an "Antennas Direct 91XG" supplier in your area.

I have stacked in a quad array this brand of antenna for a deep fringe MATV setup, it phases well if you use a good summing amp.

 

[mouse3]

Thanks,i think the same,only parabolic have 40 dB gain. I don t know what UHF antenna to choose for the focal point to collect the signal.To be one turns helix,one 3 element Yagi,I don t know yet.What do You think,what perform better for fringe ?
I think the helix perform better for both polarisation.I need to collect more signal possible.In the next two years the analogic die in my country and in the all country around me.Digital trasmission replace old analogic transmission station.
I found on internet one guy who receve digital tv station from 1200 Km away,above the sea.Looks impressive that reception,here i have mountains ahead,for this reason in the reception area only a fraction of the signal it s available.That fraction it s more below the standard reception limits.
It s impossible for me like one simple DX enthusiast to install on top of the mountains one retranslation relay.This it s the easy way to go,but the technology it s expensive and i must convert all UHF band on WI-Fi band.In this case i need power supply in that area,the UHF antenna must roatate in all directions.
I m located on 450m above sea level,on 1800m the signal it s loud and clear,but here only a fraction of signal it s available.

 

[mouse3]

Thanks for imputs Mr.Terryl, Slovak digital Tv station work on vertical polarisation,Bulgarian and Ucrainian work on horizontal,they are in digital test transmission now,thinks are blended here today.
They don t know yet what digital polarisation to chosse,and since now they replace MPEG 2 with MPEG 4.Aftet one year people buy MPEG 2 tv set ant found know that set it s uselles today.I found few funny cases where digital signal don t match exctly MPEG 2 and 4 standard,people have trouble to catch that transmission,They live near to transmission tower but found no signal on tv set,channel missing or performing bad that analogic standard.
I hope that antenna it s not expensive,supplier here don t import expensive and professional stuff,they have trouble to found buyers.I try to found for example one Chapparal and Gardiner genuine C band LNC here.In East Europe genuine parts it s missing.They are not intrested,same like SKY,they make only the programs,pirate make the cash.One montly valid subscription cost here two month pay check.
I must become first one drog and gun dealer to have that cash,girl at play and other dirty bussines.
Talking about large dishes,genuine parts,Uncle Sam must be my brother to own ones.Here one petalised 3m dish it s farr i can t go.
Do it yourself it s the only options.
We are in the Eu now,but i found strange legislation,town council and other EU crap.People are alowed only to become obese and lazy,dishes are uglly,dogs and cats ar bad,power supply it s dangerous,s_x,gin and tobacco only a little and lots of restriction like in the commy jail.
I think it s time to relocate that old ladies from town concil in the forest caves,all it s natural there,only milk and honey,lollypops and other EU crap.They wake-up only when mother bear come back at home.