ADS-B DIY Antenna

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jepolch

Active Member
Nice.. Good job..
Thanks. Unfortunately, it doesn't do anything to isolate 1090 Mhz, which is what I had hoped. I probably have some measurement off, or something. I don't have any test equipment, so all I can do is put it on the feed line and randomly turn the screws. Things change, but no improvement around 1090. As you can see from the pictures, the filter attenuates the cell phone frequencies pretty well, but doesn't do anything to improve 1090.

New baby sheep next door. :)
 

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ab cd

Senior Member
Could you describe how you have it hooked up? Do you, or anyone, know the impedance of the antenna?
Thanks,
Doug
Franklin 4 vertical elements + 2 phasing hairpins: Zant = 415-j430 ohms

Franklin 4 vertical elements + 2 phasing hairpins + 1 impedance matching stub in middle (i.e. total 3 hairpins): Zant = 75 ohms.

The coax is connected to two wires of middle hairpin, about 20mm from its round end.
 

ab cd

Senior Member
For some reason I don't seem to be getting updates from the forum anymore. I checked it and found you guys had been chatting away for a couple of days and I wasn't notified. :( I made this filter and have been experimenting with it. It works, but it's hard to know how well. It's shorted, so I can't put it on either of my antennas at this time. When the snow clears off the roof I'll put it up, but I need to add a DC blocker after the amp and then connect the filter to the antenna. Plans are here: http://www.w6pql.com/microwave_filters.htm
Well done. Very crafty. You are expert in metal work & soldering!
 

ab cd

Senior Member
I had the same issue. I thought I had cut it precisely, but apparently not.
In your case, issue is not cutting, as you are very precise and crafty. It is bad design, rather no design. Seems the designer just added coils between sections without precisely determining their dimension.

The performance of this antenna critically depeds on dimensions of the coils, and the limbs..
 

DougJohnson

New Member
Franklin 4 vertical elements + 2 phasing hairpins: Zant = 415-j430 ohms

Franklin 4 vertical elements + 2 phasing hairpins + 1 impedance matching stub in middle (i.e. total 3 hairpins): Zant = 75 ohms.

The coax is connected to two wires of middle hairpin, about 20mm from its round end.
Thanks. Can the impedance be varied by where the coax is connected? Like 50 ohms?
-- Doug
 

Sjacket99

Member
Does anyone have the command to remove flight radar 24 feeder from the Pi? I'm having issues and I want to remove it to see if it fixes the issue that I'm having. Thanks.
 

ab cd

Senior Member
I also faced this type of situation where I wanted to uninstall a particular program from my RPi. I did not know, and still dont know, how to do this in Linux.

I solved this problem by formatting my microSD card, then fresh install every thing minus the unwanted program! :D
 

ab cd

Senior Member
Is there a way to build a cheap coaxial DC blocker?
1. At the point you want to insert a DC Blocker, cut the core of coax, but make the braid electrically continous.

2. Solder a 200pF ceramic Capacitor between the two cut ends of coax core. Bingo! You DC is blocked!

(The DC blocker is nothing more than a capacitor inserted in series with the core)

You can get 30 pieces of 200pF ceramic capacitor from eBay for $0.99+Free Shipping - Ultra cheap DC Blocker :D

http://m.ebay.com/itm/250861550648

Ceramic Capacitor.jpeg
 
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xforce30164

Active Member
Its been a lot more busy than I expected the last few days. but today I made some progress =D. (Based on @obj's new code form github) I managed to store the currently active map-type in the localStorage variable. This is then used to reset the map-type as well to the defaultmaptype in the config file when you click on reset map.
In addition to that, the planeObject class can also access the map-type, and if it discovers that the map is in dark map mode, the colors of the lines change from black and reddish (for known and estimated) to green and white when you select a plane. (currently if you have a plane selected you need to deselect and reselect it for the path to update, but this should be a minor fix).

See attached screenshot ;)

dump1090color.png
 

jepolch

Active Member
Its been a lot more busy than I expected the last few days. but today I made some progress =D. (Based on @obj's new code form github) I managed to store the currently active map-type in the localStorage variable. This is then used to reset the map-type as well to the defaultmaptype in the config file when you click on reset map.
In addition to that, the planeObject class can also access the map-type, and if it discovers that the map is in dark map mode, the colors of the lines change from black and reddish (for known and estimated) to green and white when you select a plane. (currently if you have a plane selected you need to deselect and reselect it for the path to update, but this should be a minor fix).

See attached screenshot ;)

View attachment 1251
Very nice! Thanks for the update. Is this still version 1.14 of mutab?
 

jepolch

Active Member
Does anyone have the command to remove flight radar 24 feeder from the Pi? I'm having issues and I want to remove it to see if it fixes the issue that I'm having. Thanks.
If you installed it from the debian package (deb) you should be able to totally remove it using 'sudo dpkg -P fr24feed'. The "P" means purge. Try it. If it doesn't work it won't cause any other problems.
 

giacomo1989

Member
1. At the point you want to insert a DC Blocker, cut the core of coax, but make the braid electrically continous.

2. Solder a 200pF ceramic Capacitor between the two cut ends of coax core. Bingo! You DC is blocked!

(The DC blocker is nothing more than a capacitor inserted in series with the core)

You can get 30 pieces of 200pF ceramic capacitor from eBay for $0.99+Free Shipping - Ultra cheap DC Blocker :D

http://m.ebay.com/itm/250861550648

View attachment 1250
The question is how to cut a coax to solder a capacitor to the core mantaining the braid sane :) Do you suggest something?
Does this affect the signal and the coax bandwidth?
 

xforce30164

Active Member
This is a very quick sketch, but this should be one possible way to connect the capacitor
IMG_20150303_150312_1425391416735.jpg

So you actually completely cut the cable in the first step, and then strip enough outer mantle to have enough shielding available to have room between the two core conductor pieces for the capacitor. I'd first measure if the cap fits, then solder the cap first and after that the braiding/shielding.

do make sure to insulate/separate the shielding from the core and capacitor afterwards. and finally isolate the whole cable again with some heatshrink or electrical tape or something like that.
(The brown "bend" represents the shielding "rolled" into a wire-like structure on both end of the cut piece of cable and then joining/soldering them together.)

There are probably other/better/easier ways to do this but this is in short how I would probably do it.
 

giacomo1989

Member
This is a very quick sketch, but this should be one possible way to connect the capacitor
View attachment 1253
So you actually completely cut the cable in the first step, and then strip enough outer mantle to have enough shielding available to have room between the two core conductor pieces for the capacitor. I'd first measure if the cap fits, then solder the cap first and after that the braiding/shielding.

do make sure to insulate/separate the shielding from the core and capacitor afterwards. and finally isolate the whole cable again with some heatshrink or electrical tape or something like that.
(The brown "bend" represents the shielding "rolled" into a wire-like structure on both end of the cut piece of cable and then joining/soldering them together.)

There are probably other/better/easier ways to do this but this is in short how I would probably do it.
Thanks!

Do you think also this can work?
coax.png


It's just like to put the coax parallel after removing some plastic from both.. then solder the cap and solder togher all the shielding.
 

jepolch

Active Member
This is a very quick sketch, but this should be one possible way to connect the capacitor
View attachment 1253
So you actually completely cut the cable in the first step, and then strip enough outer mantle to have enough shielding available to have room between the two core conductor pieces for the capacitor. I'd first measure if the cap fits, then solder the cap first and after that the braiding/shielding.

do make sure to insulate/separate the shielding from the core and capacitor afterwards. and finally isolate the whole cable again with some heatshrink or electrical tape or something like that.
(The brown "bend" represents the shielding "rolled" into a wire-like structure on both end of the cut piece of cable and then joining/soldering them together.)

There are probably other/better/easier ways to do this but this is in short how I would probably do it.
Where'd you learn to write English so well? You write like an American (no offense, I hope). :D
 

xforce30164

Active Member
Where'd you learn to write English so well? You write like an American (no offense, I hope). :D
Haha thanks, no offence at all ;). I've played a lot of english games and watched a lot of BBC when I was a kid, and I still do. In addition to that I followed "TTO" (Bilingual Education) at high-school So for the six years in high-school I've had double the amount of English classes, had to do more stuff than the normal classes/groups etc. In the end you get an International Baccalaureate certificate if you pass the final exam that shows that you have a higher level of understanding/skill of the English language.

Edit: Oh and ofcourse the multiple holiday-visits to the USA ;) (been to california, florida, grand canyon, bryce canyon, yosemite, death valley, and more). This summer the plan is to explore more of the north-eastern part (NY, Boston, Niagara Falls etc) :D
 
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