best antenna

[abcd567]

I've been trying to source a company that makes the real ADS-B antennas used in actual ATC installations. It seems there are a few different companies out there making and developing the ADS-B systems, and they also make their own antennas for the purpose. In the following photos you'll see some actual installations and the antennas used. Most seem to be just a simple omnidirectional with a full wave length of 1090 MHz = 27.5 cm.

Thanks for the information and pictures. Fullwave DIPOLE is simple and has better gain over 1/2 wave DIPOLE, but fullwave dipole has disadvantage of having a very high impedence (say 2000 to 5000 ohms) at resonant frequency, and needs matching circuit of 5:1 to 10:1, whereas the 1/2 wave dipole has 73 ohm impedance at resonant frequency, which matches coaxial cable and receiver impedance (75 or 50 ohms) and does not need a matching circuit. Matching can be done by matching transformer, 1/4 wave stub, or balun. Fullwave collinear antenna with a feed matching stub is a good solution. I am using a Franklin collinear 4-element fullwave center-fed dipole (total height of both legs together = 54.4 cm). I am not using matching transformer or stub or balun, & geting good results. I will now add a 1/4 wave matching element and see if it gives any improvement.

[abcd567]

I've been trying to source a company that makes the real ADS-B antennas used in actual ATC installations. It seems there are a few different companies out there making and developing the ADS-B systems, and they also make their own antennas for the purpose. In the following photos you'll see some actual installations and the antennas used. Most seem to be just a simple omnidirectional with a full wave length of 1090 MHz = 27.5 cm.

Attached diagram shows 3 antennas I have built (# 1, 2, 3) and the one (#4) which I am planning to built & try shortly.

NOTE:
Currently I an using #3 but WITHOUT ANY MATCHING arrangement (1:5 is shown in diagram, but I have not installed it).
Still my coverage is over 450 km.

dipoles2.png

.

[1090 MHz]

Thanks for the information and pictures. Fullwave DIPOLE is simple and has better gain over 1/2 wave DIPOLE, but fullwave dipole has disadvantage of having a very high impedance (say 2000 to 5000 ohms) at resonant frequency

Yes you are correct about the high impedance. I have seen a full wave dipole where the wire was
fed with coax 1/4 wave in from one end. This was done to achieve a reasonable coax match.

[abcd567]

@1090 MHz: Seen your site http://www.ADS-B.ca. Great looking and impressive tower for your ADS-B antenna. You sure are going to get a good coverage with FR24 supplied professional antenna & low-loss LMR400 cable. I will keep visiting your site to see the progress of installation. Please post a screen-shot of coverage when your station is operational.

[North Borneo Radar]

@1090 MHz: Seen your site http://www.ADS-B.ca. Great looking and impressive tower for your ADS-B antenna. You sure are going to get a good coverage with FR24 supplied professional antenna & low-loss LMR400 cable. I will keep visiting your site to see the progress of installation. Please post a screen-shot of coverage when your station is operational.

So am I...

[abcd567]

Yes you are correct about the high impedance. I have seen a full wave dipole where the wire was
fed with coax 1/4 wave in from one end. This was done to achieve a reasonable coax match.

End-fed antennas are Monopoles. By definition, Dipoles are fed in the middle, breaking the antenna's total length in two parts, and hence the name "Di-pole".

A Monopole of 1/2 the length of a Dipole has characteristics very similar to that Dipole, because the Monopole is the upper pole of Dipole, and the lower pole is compensated by Ground Plane. The Monopole hence is half in height of it's equivalent Dipole.

A Dipole 1/2 wavelength is equivalent to a Monopole 1/4 wavelength, and a Dipole 1 wavelength is equivalent to a Monopole of 1/2 wavelength and so on.

Because of Monopole's size is half of an equivalent Dipole, the Monopoles were very convenient and practical on low frequencies (LW/MW/HF) where wavelengths run in tens of meters. For higher frequencies (VHF/UHF/SHF) the wavelengths are few meters or less, and Dipole becomes practical. An example is TV antenna, which we see on rooftop of most households, is always a Dipole.

The main advantage of Dipole over Monopole is that Dipole's received signal is 2 times the equivalent Monopole's received signal (2 legs vs 1 leg). This means Dipole's Gain is 3dB higher than equivalent Monopole, and the Dipole is less directional, which is more suitable for ADS-B. Having length doubled on ADS-B frequency is not a problem. That is the reason I have always used Dipoles (simple 1/2 wavelength Dipole, simple full wavelength Dipole & Franklin collinear Dipole).

[1090 MHz]

@1090 MHz: Seen your site http://www.ADS-B.ca. Great looking and impressive tower for your ADS-B antenna. You sure are going to get a good coverage with FR24 supplied professional antenna & low-loss LMR400 cable. I will keep visiting your site to see the progress of installation. Please post a screen-shot of coverage when your station is operational.

Hi Guys,

The equipment from FR24 arrived today! I have it setup and running in my house as a test in my 2nd floor office. The GPS light flashes green every second, and the S Mode like it flickering non stop showing the reception of ADS-B data.... and this is just inside my house, I can't wait to place the antenna a top the tower!

[North Borneo Radar]

Hi Guys,

The equipment from FR24 arrived today! I have it setup and running in my house as a test in my 2nd floor office. The GPS light flashes green every second, and the S Mode like it flickering non stop showing the reception of ADS-B data.... and this is just inside my house, I can't wait to place the antenna a top the tower!

Fantastic, can't wait to see pictures of it being installed!

[andyk1]

Hi Guys,

The equipment from FR24 arrived today! I have it setup and running in my house as a test in my 2nd floor office. The GPS light flashes green every second, and the S Mode like it flickering non stop showing the reception of ADS-B data.... and this is just inside my house, I can't wait to place the antenna a top the tower!

Wonder if you could open it up to show us how the beast is mounted to there beaglebone setup? Curious what GPS module they used and how they attached it. Any guess what antenna that is? doesn't seem to be long enough to be a Collinear. I am really, really curious how they made there's as save us the aggravation of guessing building our own. What range did you get testing it inside your home if you tried to measure it.

Just by Looking seems the antenna has a type N connector at the antenna end and SMA at the Box end?

[andyk1]

Hi Guys,

The equipment from FR24 arrived today! I have it setup and running in my house as a test in my 2nd floor office. The GPS light flashes green every second, and the S Mode like it flickering non stop showing the reception of ADS-B data.... and this is just inside my house, I can't wait to place the antenna a top the tower!

I am also interested in the Tower you have. Can you tell me the manufacturer? Cost. Foundation.. How deep, Wide? I know you mentioned 50 feet. Is that by legal limits where you are located?

Heheh I'd like to see pictures of you climbing that tower if possible. Should be interesting to see. Am sure you have a harness and safety equipment for that. I attempted to install my antenna on a 300 foot tower half way up and had second thoughts.

As far as lightening protection I'm not seeing it as your ads-b antenna is below the tallest point. Static protection is a must for the cable line though. On second thought after looking at your pictures of your tower I probably would to be on the safe side.

Sure would like to see the inside of that Flightradar Box Though...

Does the antenna come apart for maintenance or sealed? As I said. I'd like to see the inside how they build there's, what type.

[abcd567]

Hi Guys,

The equipment from FR24 arrived today! I have it setup and running in my house as a test in my 2nd floor office. The GPS light flashes green every second, and the S Mode like it flickering non stop showing the reception of ADS-B data.... and this is just inside my house, I can't wait to place the antenna a top the tower!

CONGRATULATIONS! The antenna is of moderate size. I wish to know what type is the antenna: a collinear, dipole or some other configuration. Waiting for your setup to complete and see screenshot of your coverage.

[1090 MHz]

Wonder if you could open it up to show us how the beast is mounted to there beaglebone setup? Curious what GPS module they used and how they attached it. Any guess what antenna that is? doesn't seem to be long enough to be a Collinear. I am really, really curious how they made there's as save us the aggravation of guessing building our own. What range did you get testing it inside your home if you tried to measure it.

Just by Looking seems the antenna has a type N connector at the antenna end and SMA at the Box end?

As much as I'd like to open it up to show you what's inside, it wasn't given to me for that purpose. The equipment is the property of Flightradar24, and I don't think they would appreciate me violating their trust. However maybe Flightradar24 can post those photos you're after?

[1090 MHz]

I am also interested in the Tower you have. Can you tell me the manufacturer? Cost. Foundation.. How deep, Wide? I know you mentioned 50 feet. Is that by legal limits where you are located?

Heheh I'd like to see pictures of you climbing that tower if possible. Should be interesting to see. Am sure you have a harness and safety equipment for that. I attempted to install my antenna on a 300 foot tower half way up and had second thoughts.

As far as lightening protection I'm not seeing it as your ads-b antenna is below the tallest point. Static protection is a must for the cable line though. On second thought after looking at your pictures of your tower I probably would to be on the safe side.

Sure would like to see the inside of that Flightradar Box Though...

Does the antenna come apart for maintenance or sealed? As I said. I'd like to see the inside how they build there's, what type.

The tower was installed in 2007 by a local company called "V & E antenna" that sadly went out of business in 2010. I'm not sure of the Towers manufacture but do recall they were specially made to order for them by a local guy. It's a brace type tower where it's supported by brackets attached to the homes brick in 2 places. It's not a "Self Supporting" type where you need a concrete foundation. My towers base is 3 feet down into the clay earth. It's a very heavy design with the extra lattice bracing. The tower is also well grounded with grounding electrodes deep in the earth.

[eddm_muc]

Wonder if you could open it up to show us how the beast is mounted to there beaglebone setup? Curious what GPS module they used and how they attached it.

If you wanna know the details, check the developer website
http://radarcape.bplaced.net/wiki/doku.php

and as for antennas check these
For those who look for the famous "Russian" antenna from RADIAL that many refer to in all ADS-B boards, you can now get a 1.5m called A9-1090 with 8.5db gain and the A10-1090 1.8m with about 10db gain from their Finish subsidiary ik-telekom.com.
They have made an online shop called duplexers.eu and both antennas are
arround 85€ plus the tax and shipping.
see here:
http://duplexers.eu/catalog/Pro/antennas/a9_1090/
http://duplexers.eu/catalog/Pro/antennas/a10_1090/

[andyk1]

As much as I'd like to open it up to show you what's inside, it wasn't given to me for that purpose. The equipment is the property of Flightradar24, and I don't think they would appreciate me violating their trust. However maybe Flightradar24 can post those photos you're after?

I more than understand. Thanks anyway.