ADS-B DIY Antenna

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ab cd

Senior Member
Spider dimensions from ARRL Antenna Handbook.
Reference point to measure the radials is different in each sketch. Very confusing.... or may be radial length has so great tolerance that nobody cares about reference point accuracy.


Spiders from ARRL Book.PNG
 
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ab cd

Senior Member
SIX LEG SPIDER


USES ONLY F-TYPE BARREL CONNECTOR (With Nut & Washer).



NO SOLERING REQUIRED.
NO SO239, BNC, or N CONNECTOR REQUIRED.

FINISHED LENGTHS
WHIP: From top of F-connector to top of whip = 69 mm
RADIALS: From Point of bending down to tip of radial = 69 mm
RADIALS BENDING DOWN: About 45 degrees below horizontal
WIRE DIA: Flexible. In this demo core wire of RG6 coax cable is used which has a dia of 1 mm (18 AWG), but wires with bigger dia can as well be used.

STEP-1
6-leg spider with F barrel Connector -1.jpg



STEP-2
6-leg spider with F barrel Connector -2.jpg



STEP-3
6-leg spider with F barrel Connector -3.jpg



ON TRIAL RUN
6-leg spider with F barrel Connector -4.jpg



DIRECTLY BUILT ON AN AMPLIFIER, INSTEAD OF F-CONNECTOR
6-leg spider with F barrel Connector -5.jpg

 
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bramj

Member
Very nice. How's the reception compared to your other coco? I've thought of making one of those brass ones, but never got around to it - plus, I've had my best luck with spiders.
Beter then the coax-colinear, at the moment its 8 elements , i will add 4 more elements later,
It's raining now, but it is performancing well

Screen Shot 2015-05-31 at 16.30.58.png



Also spotted little new plane "HON21"

https://www.hondajet.com

Screen Shot 2015-05-31 at 14.23.19.png



CESx5GOWIAIuRq3.jpg


Hmmmm, to bad its cloudy can see it..:-(

Screen Shot 2015-05-31 at 16.39.48.png
 
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jepolch

Active Member
Spider dimensions from ARRL Antenna Handbook.
Reference point to measure the radials is different in each sketch. Very confusing.... or may be radial length has so great tolerance that nobody cares about reference point accuracy.


View attachment 2154
But what I like best about the first graphic is that they show the measurement of the radial begins from the whip. Not the insulator. Not the edge of the flange. Great find.
 

jepolch

Active Member
Beter then the coax-colinear, at the moment its 8 elements , i will add 4 more elements later,
It's raining now, but it is performancing well

View attachment 2155


Also spotted little new plane "HON21"

https://www.hondajet.com

View attachment 2156


View attachment 2157

Hmmmm, to bad its cloudy can see it..:-(

View attachment 2158
I'm glad your new coco is working well. :)

I see quite a few of these new Honda jets (HON**). They are made here in North Carolina, USA. http://www.hondajet.com/

Edit: Also http://en.wikipedia.org/wiki/Honda_HA-420_HondaJet
 
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ab cd

Senior Member
But what I like best about the first graphic is that they show the measurement of the radial begins from the whip. Not the insulator. Not the edge of the flange. Great find.
Yes, in first graphic it is from whip, but in second & third graphics, it is from the corner of flange where the bend starts. So which one is right, 1st or 2nd/3rd?

Also, ARRL Handbook shows only 4 legs in all 3 grahics, so from where 8 legged version popped up?
 

jepolch

Active Member
Yes, in first graphic it is from whip, but in second & third graphics, it is from the corner of flange where the bend starts. So which one is right, 1st or 2nd/3rd?

Also, ARRL Handbook shows only 4 legs in all 3 grahics, so from where 8 legged version popped up?
I think in the third graphic they don't say it, but they imply the difference between A and B is the distance from the edge of the flange to the whip, which I think is 5/8". Add B + 5/8" and you get A. Do you agree? I agree the graphic is confusing, the way they write the number 19 -5/16 instead of 19 5/16 or 19.3125. Add 18 + .6875 (11/16) + .625 (5/8) = 19.3125.

As for the 8 legged spider, I guess it was a natural evolution. More is better. :D
 

ab cd

Senior Member
I think in the third graphic they don't say it, but they imply the difference between A and B is the distance from the edge of the flange to the whip, which I think is 5/8". Add B + 5/8" and you get A. Do you agree? I agree the graphic is confusing, the way they write the number 19 -5/16 instead of 19 5/16 or 19.3125. Add 18 + .6875 (11/16) + .625 (5/8) = 19.3125.

As for the 8 legged spider, I guess it was a natural evolution. More is better. :D
Yes, you are right about 3rd graphic that the length from whip is implied, but in 2nd graphic it is explicitly and clearly from bending point.

Well as regards writing fractions with a dash in between whole number & fractional part (like 1-3/16), has been a centuries old convention, and possibily originated to avoid mistake in reading if dash after the whole number is removed (1-3/16 can easily be read as 13/16 if dash is removed).
 

ab cd

Senior Member
Wow, that's a great piece of history there and easy to read, too. I'm surprised they didn't include a larger, more detailed picture of the antenna itself.
You are right. In the diagrams at last page, antenna itself is not at all clear unless one carefully reads and understands the whole text.

Fig2 shows a vertical Monopole, 3 x ½ wavelength, fed at bottom. Radiation pattern is like a 6-petal flower, a highly undesireable radiation pattern.

Figure 3 shows the same antenna, but with middle ½ wavelength section collapsed upon itself. Due to folding, the middle ½ wavelength vertical wire is now a ¼ wavelength horizontal stub in the middle. The radiation patter changes from 6-petal flower to lazy 8** (a highly desireable radiation pattern), and the Franklin collinear is born.

**Imagine that 8 has become lazy, and instead of standing upright, is lying in bed ∞ . :)
 
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jepolch

Active Member
Yes, you are right about 3rd graphic that the length from whip is implied, but in 2nd graphic it is explicitly and clearly from bending point.
Oh yeah, I see that now. Well, I would go with two out of three and measure from the whip. I haven't changed any of my antennas yet. I wonder how much of a difference it will make?

Well as regards writing fractions with a dash in between whole number & fractional part (like 1-3/16), has been a centuries old convention, and possibily originated to avoid mistake in reading if dash after the whole number is removed (1-3/16 can easily be read as 13/16 if dash is removed).
Now that you mention it I guess I have seen it, but centuries ago. :D
 

Todd

New Member
One last plea from a member who values your sage input...

I know some of you run dump78 mutability. I have a spider cut for 978 Mhz and an inline amp. When I use SDR# on my W7 laptop, I see the characteristic spectrum at ~ 977.7 Mhz. I have installed a Virtualbox Ubuntu on my Imac, which is available to serve as my computer for 978 UAT transmissions, which I am very interested in decoding. I have RTL-SDR and Dump978 on the Vbox....when I enter the command for UAT:


todd@todd-VirtualBox:~$ rtl_sdr -f 978000000 -s 2083334 -g 48 - | ./dump978

-bash: ./dump978: Is a directory

Found 1 device(s):

0: Generic, RTL2832U, SN: 77771111153705700


Using device 0: Generic RTL2832U

Found Rafael Micro R820T tuner

Exact sample rate is: 2083334.141630 Hz

Sampling at 2083334 S/s.

Tuned to 978000000 Hz.

Tuner gain set to 48.00 dB.

Reading samples in async mode...

Signal caught, exiting!

Short write, samples lost, exiting!


User cancel, exiting...

And if I try RTL_test, I get:

todd@todd-VirtualBox:~/rtl-sdr/build/src$ ./rtl_test

Found 1 device(s):

0: , RTL2832U, SN: 77771111153705700


Using device 0: Generic RTL2832U

Found Rafael Micro R820T tuner

Supported gain values (29): 0.0 0.9 1.4 2.7 3.7 7.7 8.7 12.5 14.4 15.7 16.6 19.7 20.7 22.9 25.4 28.0 29.7 32.8 33.8 36.4 37.2 38.6 40.2 42.1 43.4 43.9 44.5 48.0 49.6

Sampling at 2048000 S/s.


Info: This tool will continuously read from the device, and report if

samples get lost. If you observe no further output, everything is fine.


Reading samples in async mode...

lost at least 64 bytes

lost at least 48 bytes

lost at least 88 bytes

lost at least 48 bytes

lost at least 208 bytes

lost at least 20 bytes


I have been working with OBJ, but I seem not to be able to communicate clearly abt the problem

Please help, guys
Todd
 

jepolch

Active Member
One last plea from a member who values your sage input...

I know some of you run dump78 mutability. I have a spider cut for 978 Mhz and an inline amp. When I use SDR# on my W7 laptop, I see the characteristic spectrum at ~ 977.7 Mhz. I have installed a Virtualbox Ubuntu on my Imac, which is available to serve as my computer for 978 UAT transmissions, which I am very interested in decoding. I have RTL-SDR and Dump978 on the Vbox....when I enter the command for UAT:


todd@todd-VirtualBox:~$ rtl_sdr -f 978000000 -s 2083334 -g 48 - | ./dump978

-bash: ./dump978: Is a directory

Found 1 device(s):

0: Generic, RTL2832U, SN: 77771111153705700


Using device 0: Generic RTL2832U

Found Rafael Micro R820T tuner

Exact sample rate is: 2083334.141630 Hz

Sampling at 2083334 S/s.

Tuned to 978000000 Hz.

Tuner gain set to 48.00 dB.

Reading samples in async mode...

Signal caught, exiting!

Short write, samples lost, exiting!


User cancel, exiting...

And if I try RTL_test, I get:

todd@todd-VirtualBox:~/rtl-sdr/build/src$ ./rtl_test

Found 1 device(s):

0: , RTL2832U, SN: 77771111153705700


Using device 0: Generic RTL2832U

Found Rafael Micro R820T tuner

Supported gain values (29): 0.0 0.9 1.4 2.7 3.7 7.7 8.7 12.5 14.4 15.7 16.6 19.7 20.7 22.9 25.4 28.0 29.7 32.8 33.8 36.4 37.2 38.6 40.2 42.1 43.4 43.9 44.5 48.0 49.6

Sampling at 2048000 S/s.


Info: This tool will continuously read from the device, and report if

samples get lost. If you observe no further output, everything is fine.


Reading samples in async mode...

lost at least 64 bytes

lost at least 48 bytes

lost at least 88 bytes

lost at least 48 bytes

lost at least 208 bytes

lost at least 20 bytes


I have been working with OBJ, but I seem not to be able to communicate clearly abt the problem

Please help, guys
Todd
Sorry. I have no clue. I've only run dump1090-mutability on Raspbian Wheezy. obj would be the best one to help. Good luck.
 

Todd

New Member
Thanks, jepolch.

We finally figured it out :) a Linux noob issue on my part!
UAT looks interesting..weather and other info to digest

Todd
 

giacomo1989

Member
One last plea from a member who values your sage input...

I know some of you run dump78 mutability. I have a spider cut for 978 Mhz and an inline amp. When I use SDR# on my W7 laptop, I see the characteristic spectrum at ~ 977.7 Mhz. I have installed a Virtualbox Ubuntu on my Imac, which is available to serve as my computer for 978 UAT transmissions, which I am very interested in decoding. I have RTL-SDR and Dump978 on the Vbox....when I enter the command for UAT:


todd@todd-VirtualBox:~$ rtl_sdr -f 978000000 -s 2083334 -g 48 - | ./dump978

-bash: ./dump978: Is a directory

Found 1 device(s):

0: Generic, RTL2832U, SN: 77771111153705700


Using device 0: Generic RTL2832U

Found Rafael Micro R820T tuner

Exact sample rate is: 2083334.141630 Hz

Sampling at 2083334 S/s.

Tuned to 978000000 Hz.

Tuner gain set to 48.00 dB.

Reading samples in async mode...

Signal caught, exiting!

Short write, samples lost, exiting!


User cancel, exiting...

And if I try RTL_test, I get:

todd@todd-VirtualBox:~/rtl-sdr/build/src$ ./rtl_test

Found 1 device(s):

0: , RTL2832U, SN: 77771111153705700


Using device 0: Generic RTL2832U

Found Rafael Micro R820T tuner

Supported gain values (29): 0.0 0.9 1.4 2.7 3.7 7.7 8.7 12.5 14.4 15.7 16.6 19.7 20.7 22.9 25.4 28.0 29.7 32.8 33.8 36.4 37.2 38.6 40.2 42.1 43.4 43.9 44.5 48.0 49.6

Sampling at 2048000 S/s.


Info: This tool will continuously read from the device, and report if

samples get lost. If you observe no further output, everything is fine.


Reading samples in async mode...

lost at least 64 bytes

lost at least 48 bytes

lost at least 88 bytes

lost at least 48 bytes

lost at least 208 bytes

lost at least 20 bytes


I have been working with OBJ, but I seem not to be able to communicate clearly abt the problem

Please help, guys
Todd
You cannot run it in virtualbox.. Virtualization is too slow and data can't keep a constant pace.
 

ab cd

Senior Member
The crashes of dump1090-mutability
22 times in last 3 weeks! :mad:

I had to manually reboot RPi, as restarting dump1090-mut was not enough. Collectd & pfclient often wont reconnect to dump1090-mut even after dump1090's restart.

Now I have done this to automatically reboot RPi:
Code:
sudo crontab -e
#above command opened crontab file for editing
#added following below last line of file
0 4,10,16,22  *  *  *  sudo reboot
#my time offset from UTC is -4 hrs, 
# 4,10,16,22 hrs utc is 0,6,12,18 hrs local time
#saved (ctrl+o) and exit (ctrl+x)
#message displayed: 
crontab:  installing new crontab
dump1090-rpi-cpu-30d.png
 
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ab cd

Senior Member
After 2½ day's trial run, the 6-legged F-connector spider is getting roughly 20% more positions than 4-legged SO239 spider. This may also be due to day to day fluctuations of traffic. I cant be very sure due to frequent crashes of dump1090-mut .....Grrrrrr.
 
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