ADS-B DIY Antenna

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ab cd

Senior Member
Thanks so much for doing this.

Don't you think is realy strange that dipole has better SWR than the spider? Maybe there are some considerations about the feeding point that the program does not count
I have read in many authentic books that a ½ wavelength has 75 ohms impedance (i.e. SWR for 75 ohm system is 1), and gain of 2.2 dBi. The groundplane antennas (horizontal disk, horizontal radials, and slanting radials) are all theoretically close, but inferior to dipole. The main reason ground plane are popular over plain dipole is convinience of bottom fed arrangement used by all types of groundplanes, over side fed arrangement used by dipole.

Remember, all Yagis have only one driven element - a dipole (or folded dipole). Those who remember rooftop TV antennas, can easily realize success of dipole or folded dipole. Th folded dipole was used with twin-lead (300 ohms), and the straight dipole was used with coax (75 ohms). The directivity was imparted to omni dipole by elements placed in front & back of dipole (but not connected to dipole or feed cable), making a typical TV antenna.
 
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PeterPlane

New Member
Move to the country. My neighbor raises sheep. :) (quiet, no smell)

Making those antennas must be a major cottage industry in Bulgaria. :D I'm tempted to take the plunge for one of those, too, but I'm just worried there's just a little whip inside it like the one that comes with the dongle. If anyone gets one and thinks it's a good buy, I may have to get one.
The seller assured me that they are made of FR4 (circuit boards). I guess we'll see. I don't really care what's inside, I want to see what it does to my numbers...
 

Sjacket99

Member
The seller assured me that they are made of FR4 (circuit boards). I guess we'll see. I don't really care what's inside, I want to see what it does to my numbers...

A person from Flight aware site said the following about the antennas on eBay from that seller. "professionally made antenna by ANTENI.NET Ltd"

The seller has a lot of good feed back from people buying them,
 

jepolch

Active Member
The seller assured me that they are made of FR4 (circuit boards). I guess we'll see. I don't really care what's inside, I want to see what it does to my numbers...
That's what I'm interested in, too. Do you have any idea what an antenna made of circuit boards would look like? Why does the tube need to be so long?
 

jepolch

Active Member
A person from Flight aware site said the following about the antennas on eBay from that seller. "professionally made antenna by ANTENI.NET Ltd"

The seller has a lot of good feed back from people buying them,
I'm certainly curious what your results will be like. I'm just a little too timid and/or cheap to spend the 60-odd bucks unless it's the real deal.
 

PeterPlane

New Member
That's what I'm interested in, too. Do you have any idea what an antenna made of circuit boards would look like? Why does the tube need to be so long?
This is what the seller sent me in an email:

"Hi,
It is colinear 4 elements , PCB build, DC grounded antenna. The
material is FR4.
Regards"
 

Sjacket99

Member
I was able to setup and get things working on my Netbook that is feeding Flight aware, now also feeding Flight radar24. Piaware and flight radar24 running on the Netbook.
 

ab cd

Senior Member
The Magic of Dipole
The Yagi is basically a Dipole, with several electrically un-connected limbs placed in front & back of Dipole to modify it's directivity from omni-directional to uni-directional

Yagi-Uda 2.jpg . Yagi_Uda-2.png . Yagi-Uda on Tower.jpg


This WWII Me 110 night fighter features the prominent Yagi arrays of its FuG 220 radar.
FuG_220_and_FuG_202_radar_of_Me_110_1945.jpg
 
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ab cd

Senior Member
Has anyone tried these antennas advertised on eBay?
They claim 7 dBi & 10 dBi Gain on GSM
(850/1900/900/1800/2100Mhz GSM/UMTS/3G omnidirectional Antenna 10dbi SMB, 987mm)


Coiled Whips 1.JPG . Coiled Whips 2.JPG . Coiled Whips 3.JPG
 

jepolch

Active Member
Hmmm. It occurs to me - does it matter which way you install your dipole? Meaning, which end should point up? The part connected to the center element, or the braid?? I went back and found the attached diagram originally uploaded by ab cd. It shows the center element pointing up. Now I am wondering how I installed the dipole on the roof yesterday?
 

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Sjacket99

Member
[QUOTEjepolch, post: 2654, member: 927"]Running Linux, I assume?[/QUOTE]

Yes. Im running Xubuntu on it. But I rebooted my Netbook last night. And now thrflight radar24 won't start up. How do you start up the program. Piaware starts up when the computer powers up.
 

jepolch

Active Member
[QUOTEjepolch, post: 2654, member: 927"]Running Linux, I assume?
Yes. Im running Xubuntu on it. But I rebooted my Netbook last night. And now thrflight radar24 won't start up. How do you start up the program. Piaware starts up when the computer powers up.
I have this line near the end of /etc/rc.local - just before "exit 0". fr24feed_arm-rpi_242 is located in /usr/bin.
Code:
/usr/bin/fr24feed_arm-rpi_242 --fr24key=sharing_key >> /dev/null &
 

jepolch

Active Member
Check out the difference between the CPU load of these two Pi's. Both are running dump1090-mutab. The one on the left is running Piaware and FR24. The one on the right is running Piaware and PlaneFinder, i.e., node. Node.js is a hog!
 

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giacomo1989

Member
I have this line near the end of /etc/rc.local - just before "exit 0". fr24feed_arm-rpi_242 is located in /usr/bin.
Code:
/usr/bin/fr24feed_arm-rpi_242 --fr24key=sharing_key >> /dev/null &
You are using a very old feeder! The newer one has better performance and more data consistency checks.
Use this one: http://forum.flightradar24.com/threads/7563-Flightradar24-decoder-feeder-BETA-testing-(Win-RPi-Linux-OSX)
Has anyone tried these antennas advertised on eBay?
They claim 7 dBi & 10 dBi Gain on GSM
(850/1900/900/1800/2100Mhz GSM/UMTS/3G omnidirectional Antenna 10dbi SMB, 987mm)


View attachment 1085 . View attachment 1086 . View attachment 1087
Isn't too much for an omni antenna? :) :) :)
 
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