best antenna

[abcd567]

Yep, Strange as it is mine won't work with two amps connected at the same time. With one at the mast head works great. Thanks for the response. Then again maybe I do need a more power going to both.

Possibly you're over-driving and saturating the 2nd amp, you'll see no signal out if this happens.

Possibility # 1: If your power supply is very small capacity, then replacing it with a bigger one may improve. Check the power requirement of your Amplifiers, and the capacity of your power supply.

Possibility # 2: As 1090 MHz says "Possibly you're over-driving and saturating the 2nd amp, you'll see no signal out if this happens"

Possibility # 3: The unit you are using as your second Amp is defective. Purchase another one and try it as second Amp. I am saying this from my own bitter experience. The first one I ordered from eBay, did not work. I spent days to figure out and try changes to my setup, but no result. Then I purchased RCA one from a neighborhood store, and It worked great. Then I purchased 2nd one from the same store and that one is also working very good.


.

[andyk1]

Possibility # 1: If your power supply is very small capacity, then replacing it with a bigger one may improve. Check the power requirement of your Amplifiers, and the capacity of your power supply.


Possibility # 2: As 1090 MHz says "Possibly you're over-driving and saturating the 2nd amp, you'll see no signal out if this happens"

Possibility # 3: The unit you are using as your second Amp is defective. Purchase another one and try it as second Amp. I am saying this from my own bitter experience. The first one I ordered from eBay, did not work. I spent days to figure out and try changes to my setup, but no result. Then I purchased RCA one from a neighborhood store, and It worked great. Then I purchased 2nd one from the same store and that one is also working very good.


.

Mine is the same as yours. 14-18v and 25-40mA requirement. PSU I am using off an old radio shack TV Amp is 200mA so I guessed it was enough to drive both.

Makes sense. Didn't think one could be bad. Like you said I may be overpowering the second. Come to think of it now that you mentioned it I do remember you saying that in one of your previous post. Yep there cheap enough the just get another.

[fungus]

I thought this may be an appropriate place to add this point about antennas, although not what one would call technical.

You can have the best antenna in the world and if it is blocked from aircraft signals by any objects it wont be effective. One of my neighbours has just removed a very large gumtree in his backyard (I live in the 'burbs') and it has opened up an area to my north from about 130NM to in excess of 200nm which I previously couldnt pick up. Fortuitously it is on both arrival and departing tracks from SYD and MEL/BNE. Obstructions are the ADS-B antennas worst enemy. I was absolutely staggered by the difference due to one tree.... now to get rid of mine.

Regards,
Gregg.

[abcd567]

I thought this may be an appropriate place to add this point about antennas, although not what one would call technical.

You can have the best antenna in the world and if it is blocked from aircraft signals by any objects it wont be effective. One of my neighbours has just removed a very large gumtree in his backyard (I live in the 'burbs') and it has opened up an area to my north from about 130NM to in excess of 200nm which I previously couldnt pick up. Fortuitously it is on both arrival and departing tracks from SYD and MEL/BNE. Obstructions are the ADS-B antennas worst enemy. I was absolutely staggered by the difference due to one tree.... now to get rid of mine.

Regards,
Gregg.

Very true. I am blocked in many directions by buildings surrounding my location. Luckily these buildings are at some distances, so the area/angle blocked by each is not big. Even the best antenna cannot increase the range. Only way is to install antenna at a height more than the height of obstructing building or tree.

[Birdie]

One of my neighbours has just removed a very large gumtree in his backyard (I live in the 'burbs') and ....

Regards,
Gregg.

With the big gumtree removed, where do that poor "kookaburra" lives in now ?

Did you prepare a spare space in your garage for it to live in ?

http://www.sweethappylife.com/2011/activities/children-songs-lyrics/song-of-the-week-kookaburra/

http://www.youtube.com/watch?feature=player_embedded&v=S0ZbykXlg6Q

Kookaburra-200x300.jpg

[1090 MHz]

Even the best antenna cannot increase the range. Only way is to install antenna at a height more than the height of obstructing building or tree.

At the same time even a simple 0dBd gain antenna, like the one provided with the FR24 radio, can provide outstanding results if it's installed high enough to clear any local obstructions. The only upgrade I did was to use LMR-400 cable. My tower has a good vantage point looking towards the CYYZ airfield. I'm clearly looking right down at CYYZ with a height advantage of 150 feet (Tower + Elevation gain).

Also I have watched the FR24 website, for flights travailing in all directions, to see how long the flights stays locked to F-CYYZ2. I have seen the FR24 site using my tower for distances of up to 350 Km away. I can track flights on the local radar terminal for over 400 Km but it seems the signal remains strong up to 350 Km after which it starts to roll off as the aircraft fall behind the horizon.

So what this suggests is it's all about the height and not so much the antenna. Also the use of a good quality low loss coax like LMR-400 will compensate for any loss over the longer cable run without the use of any amplifiers.

F-CYYZ2.jpg

[fungus]

With the big gumtree removed, where do that poor "kookaburra" lives in now ?

Did you prepare a spare space in your garage for it to live in ?

You're kidding Birdie-
have a look at my post re the fires here in Australia- houses and gum trees dont go together. The fires have destroyed more trees (and houses) than we ever could. Do you live in a cave?

e.g. check some of the following pics (click on 'watch' on the following, with all due respect, no need to worry about the kookaburra mate with more than 200 homes destroyed);

http://www.news.com.au/breaking-news/national/emergency-warning-issued-for-blue-mtns/story-e6frfku9-1226743004598

Regards,
Gregg

[1090 MHz]

You're kidding Birdie-
have a look at my post re the fires here in Australia- houses and gum trees dont go together. The fires have destroyed more trees (and houses) than we ever could. Do you live in a cave?

Regards,
Gregg

They basically are made out of Jet Fuel Virgin Australia Researching Eucalyptus Leaves As Jet Fuel

http://online.wsj.com/news/articles/SB10001424052702303544604576429063799381464

As for the Kookaburra... oh well he's cooked.

[North Borneo Radar]

At the same time even a simple 0dBd gain antenna, like the one provided with the FR24 radio, can provide outstanding results if it's installed high enough to clear any local obstructions. The only upgrade I did was to use LMR-400 cable. My tower has a good vantage point looking towards the CYYZ airfield. I'm clearly looking right down at CYYZ with a height advantage of 150 feet (Tower + Elevation gain).

Also I have watched the FR24 website, for flights travailing in all directions, to see how long the flights stays locked to F-CYYZ2. I have seen the FR24 site using my tower for distances of up to 350 Km away. I can track flights on the local radar terminal for over 400 Km but it seems the signal remains strong up to 350 Km after which it starts to roll off as the aircraft fall behind the horizon.

So what this suggests is it's all about the height and not so much the antenna. Also the use of a good quality low loss coax like LMR-400 will compensate for any loss over the longer cable run without the use of any amplifiers.

[ATTACH=CONFIG]2788[/ATTACH]

yes, there's the popular saying: height is king for ADS-B.

[fungus]

They basically are made out of Jet Fuel Virgin Australia Researching Eucalyptus Leaves As Jet Fuel

http://online.wsj.com/news/articles/SB10001424052702303544604576429063799381464

As for the Kookaburra... oh well he's cooked.

Very interesting article, thanks

Regards,
Gregg

[abcd567]

yes, there's the popular saying: height is king for ADS-B.

The height of ADS-B RECEIVING Antenna is "King" if it exceeds the height of obstructing object. Please see attached sketch.

Antenna-Height-and-Range.jpg

[abcd567]

............So what this suggests is it's all about the height and not so much the antenna.......

The range is mainly determined by height of Aircraft. Receiving Antenna's height has relatively very little contribution to it. The height of ADS-B Antenna makes a difference only if there are tall objects surrounding it. Even in this case, the height of antenna will make an appreciable difference only if it is nearly equal or exceeds the height of obstructing object.

In your case probably you don't have any tall buildings nearby.

Please see attached sketch.

Antenna Height and Range.jpg

NOTE: For Ground-to-Ground communications, heights of both the Transmitting and Receiving antennas contribute to the range
appreciably.

[peterhr]

There's a little calculator here http://www.ringbell.co.uk/info/hdist.htm that works out horizon distance depending on observer height

It suggests for an antenna at 38000 feet the horizon is about 240 miles, then if you have another antenna at 50 feet - that has a horizon of 8.7 miles - so without obstructions, it suggests a plane at 38000 feet would be observable at about 250 miles (that's about 400 km). If you wew able to put your antenna at menawn cliffs in Ireland 1381 ft overlooking the sea - that will add 45 miles to the range.

Of course planes at 38000 feet would see each other at 480 miles ... this is all assuming that the receiving system is sensitive enough to pick up the signals, and that is dependent on the sensitivity of the antenna and the receiver and not getting too much signal loss in co-ax etc.

A little added to antenna heights can go a long way to getting a clear signal path past local trees and roof peaks - but can bring their own problems caused by tying to support something that's poked up into the turbulent air and might attract lightening.

[1090 MHz]

The range is mainly determined by height of Aircraft. Receiving Antenna's height has relatively very little contribution to it. The height of ADS-B Antenna makes a difference only if there are tall objects surrounding it. Even in this case, the height of antenna will make an appreciable difference only if it is nearly equal or exceeds the height of obstructing object.

In your case probably you don't have any tall buildings nearby.

Yes, that was my point too ... as long as you can clear local obstructions In my case I've achieved that by placing the antenna 50 feet above the ground. This is high enough to clear all roofs and trees in the area.

Also my location lines up with runways 06R & 06L (Landings) and 24R & 24L (Take-offs) so I'm getting the flights directly overhead too.

See my photos taken from antenna height on the tower.

[1090 MHz]

There's a little calculator here http://www.ringbell.co.uk/info/hdist.htm that works out horizon distance depending on observer height........

It suggests a plane at 38000 feet would be observable at about 250 miles (that's about 400 km). ..................

trying to support something that's poked up into the turbulent air and might attract lightening.

Well the equation is correct, its theoretical limit of 400Km is now a proven fact.

As for lightning, the tower was designed with that in mind. It has multiple grounding electrodes at its base, and all cabling has lightning protection including the LMR-400 from the ADS-B antenna. I learned all about lightning protection and EMP hardening back in the 1980's, when I worked on a Military project for 3 years. If a Nuke goes off the EMP has the same effect as being stuck by lightning, so the same principles of protection are used.