ADS-B DIY Antenna

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jepolch

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Congratulations!
Did you check if your existing amplifier gets DC power?
I did not because I don't have it connected to the antenna right now. However, when I did have it all hooked up, I unplugged the power source for a little while and my reception went to zero. Plugged it back in and my reception went back up. I'm assuming that means the amp was getting power.

Just finished my 8-element coco and I'm about to hook it to the receiver, but I have a couple of things to do first. I'll hook it up with the next hour or so. I had to run to Walmart to buy a new multimeter because my old one gave up the ghost after 30 some odd years. The element broke off one of the probes so I took it as a sign that I was due for a new one. New one has digital display.
 

jepolch

Active Member
Got my new antenna installed, but so far just running it inside the window. I'll get it outside within the week, hopefully. I tested it for shorts and it was OK. I used hot glue between the sections and then electrical tape over that. It will be housed in PVC piping when it goes outside. Reception seems better. By the way, you can see my coverage here: http://pi2dubya.ddns.net
 

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ab cd

Senior Member
Got my new antenna installed, but so far just running it inside the window. I'll get it outside within the week, hopefully. I tested it for shorts and it was OK. I used hot glue between the sections and then electrical tape over that. It will be housed in PVC piping when it goes outside. Reception seems better. By the way, you can see my coverage here: http://pi2dubya.ddns.net
That is great! Congratulations. How far you can pick the planes? I pick up to 250 nautical miles (450 kms). When you mount it up, you will get better range.
 

jepolch

Active Member
That is great! Congratulations. How far you can pick the planes? I pick up to 250 nautical miles (450 kms). When you mount it up, you will get better range.
Currently, 65% are <50nm. 35% are 50-100nm. I only get a few 100-150nm per day.
 

ab cd

Senior Member
Currently, 65% are <50nm. 35% are 50-100nm. I only get a few 100-150nm per day.
You will get much better range if you mount antenna on roof top.
Range will further improve by 50 to 100 nm when amplifier is added.

Questions:
Is your 8-element antenna made up of RG59 or RG6?
What is the element length?
Does it have a twin-lead adjuster? If yes, have you mechanically protected the twin-lead?

The twin-lead is a weak point mechanically and can with mechanical forces like wind or weight of downward feeder coax, can turn & twist causing short-circuit, pull out, and push in. I suggest that you initially try CoCo without twin-lead, and later when all goes well, replace bottom element with the twin-lead type.
 

jepolch

Active Member
You will get much better range if you mount antenna on roof top.
Range will further improve by 50 to 100 nm when amplifier is added.

Questions:
Is your 8-element antenna made up of RG59 or RG6?
What is the element length?
Does it have a twin-lead adjuster? If yes, have you mechanically protected the twin-lead?

The twin-lead is a weak point mechanically and can with mechanical forces like wind or weight of downward feeder coax, can turn & twist causing short-circuit, pull out, and push in. I suggest that you initially try CoCo without twin-lead, and later when all goes well, replace bottom element with the twin-lead type.
I built the antenna from the plans found here: http://www.arrl.org/files/file/QST/This Month in QST/January 2014/VirtualRadarJan2013QST.pdf
I liked how the guy used inches instead of millimeters, so it was easier for me to measure and cut. If you look at the plans you'll see the guy left 1/8" gap between the elements. Not sure why, but I did it that way and put hot glue in the gaps. I'll probably make more antennas and try out different configurations. I do want try your cantenna pretty soon.
 

ab cd

Senior Member
I built the antenna from the plans found here: http://www.arrl.org/files/file/QST/This Month in QST/January 2014/VirtualRadarJan2013QST.pdf
I liked how the guy used inches instead of millimeters, so it was easier for me to measure and cut. If you look at the plans you'll see the guy left 1/8" gap between the elements. Not sure why, but I did it that way and put hot glue in the gaps. I'll probably make more antennas and try out different configurations. I do want try your cantenna pretty soon.
Thanks for the information.

By the way 4.5" = 114.3 mm. So for all practical purposes, element lengths are same for my design (114mm) & ARRL design (4.5"). The only difference is in the presence/absence of the 1/8" gap, and the whip at top.

When I find time, I will make the ARRL one with inch measure (4.5")+1/8" gap+whip at top, and another one with metric measure (114mm) without 1/8" gap and without whip, put both on trial runs, and compare results.
 
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ab cd

Senior Member
......I liked how the guy used inches instead of millimeters, so it was easier for me to measure and cut.........
map-of-countires-that-use-metric-system-vs-imperial.0.jpg

Liberia, Myanmar, and the United States are the only countries that don't use the metric system
As Vox’s Susannah Locke wrote, "The measuring system that the United States uses right now isn’t really a system at all. It’s a hodgepodge of various units that often seem to have no logical relationship to one another — units collected throughout our history here and there, bit by bit. Twelve inches in a foot, three feet in a yard, 1,760 yards in a mile." That’s why the rest of the world uses the metric system, where "all you need to do is multiply or divide by some factor of ten. 10 millimeters in a centimeter, 100 centimeters in a meter, 1,000 meters in a kilometer. Water freezes at 0°C and boils at 100°C."
 

jepolch

Active Member
View attachment 621
Liberia, Myanmar, and the United States are the only countries that don't use the metric system
As Vox’s Susannah Locke wrote, "The measuring system that the United States uses right now isn’t really a system at all. It’s a hodgepodge of various units that often seem to have no logical relationship to one another — units collected throughout our history here and there, bit by bit. Twelve inches in a foot, three feet in a yard, 1,760 yards in a mile." That’s why the rest of the world uses the metric system, where "all you need to do is multiply or divide by some factor of ten. 10 millimeters in a centimeter, 100 centimeters in a meter, 1,000 meters in a kilometer. Water freezes at 0°C and boils at 100°C."
Wow. Now it all makes sense. See, I'm from Myanmar but I live in the US and I vacation in Liberia. So I never noticed anything odd. :p
 

jepolch

Active Member
ab cd, would I need to do anything to add a second antenna to my receiver other than put two antennas into a splitter and out of the splitter to the receiver?
 

jepolch

Active Member
VERY IMPORTANT: DO NOT connect power spply without first inserting a DC Blocking Capacitor between Amplifier and Antenna..

The reason is that Franklin, Slim Jim, and J-Pole antennas all have a shorted stub, through which DC will short and fry your inserter & DC Adaptor.

If you do not have a capacitor, you can use 2nd power inserter between amplifier and antenna, but WITHOUT connecting DC adaptor to it. I will post a drawing showing how to do this.


.
I'm going back and reading this thread from the beginning. :) Where can I get a DC blocking capacitor, or is it something you have to make yourself.
 

ab cd

Senior Member
I'm going back and reading this thread from the beginning. :) Where can I get a DC blocking capacitor, or is it something you have to make yourself.
1) You can purchase an in-line dc blocker to be inserted between amplifier & antenna:

US $4.29 + $7.65 USPS First Class Mail:
http://www.ebay.com/itm/NEW-Coaxial...g-In-Line-Coupler-25-7901-14668-/251432963230

$_3R2.PNG


US $4.99 + FREE Standard Shipping:
http://www.ebay.com/itm/NEW-Coaxial...oltage-Blocking-In-Line-Coupler-/331117426699

Pack of 10 - US $31.96 + FREE Standard Shipping:
http://www.ebay.com/itm/In-Line-Blocking-Capacitors-ID-46409-/141426807713

2)You can use another power inserter between amplifier & Antenna to act as DC Blocker. See Post # 97 on page 5

3) You can make your own DC blocker & Power inserter. See Post #88 & #89 on page 5.
 
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jepolch

Active Member
1) You can purchase an in-line dc blocker to be inserted between amplifier & antenna:

US $4.29 + $7.65 USPS First Class Mail:
http://www.ebay.com/itm/NEW-Coaxial...g-In-Line-Coupler-25-7901-14668-/251432963230

US $4.99 + FREE Standard Shipping:
http://www.ebay.com/itm/NEW-Coaxial...oltage-Blocking-In-Line-Coupler-/331117426699

Pack of 10 - US $31.96 + FREE Standard Shipping:
http://www.ebay.com/itm/In-Line-Blocking-Capacitors-ID-46409-/141426807713

2)You can use another power inserter between amplifier & Antenna to act as DC Blocker. See Post # 97 on page 5

3) You can make your own DC blocker & Power inserter. See Post #88 & #89 on page 5.
"Voltage blocking in-line coupler" - brilliant! I could search eBay if I knew what I was looking for!
 

jepolch

Active Member
I'm taking a break from installing my 8-element coco outside. I have my own bamboo grove, so I cut a couple of big ones to use as poles til something better comes along. I'll join them to a steel pole that is anchored in the ground with concrete. Soon as I catch my breath. Asthma is not your friend. :eek:
 

jepolch

Active Member
Well, I put up the new antenna and something has gone wrong. My reception is a lot worse. It must be the cable I used to feed it to the receiver - or the length of the cable. I went from about 3 feet to about 28 feet of cable - all RG59. The base of the antenna is about 11 feet off the ground. I guess I'm going to have to put in the amplifier as soon as the new one gets here from eBay. Wow, what a disappointment. I was hoping my reception would double or maybe even triple. Before.jpg After.jpg New Antenna.jpg
 

ab cd

Senior Member
Well, I put up the new antenna and something has gone wrong. My reception is a lot worse. It must be the cable I used to feed it to the receiver - or the length of the cable. I went from about 3 feet to about 28 feet of cable - all RG59. The base of the antenna is about 11 feet off the ground. I guess I'm going to have to put in the amplifier as soon as the new one gets here from eBay. Wow, what a disappointment. I was hoping my reception would double or maybe even triple. View attachment 622 View attachment 623 View attachment 624
RG59 has an attenuation of 8 dB/100ft.
28 ft of RG59 gives an attenuation of 8 x 28/100 = 2.24 dB, not a big deal, as you are using 8-element coco which can easily cover 2.24 dB loss in cable as it is supposed to have 8.5 dB gain if (and this is a big IF) the CoCo is:
(1) Perfectly Designed.
(2) Perfectly Built.

Since your Coco is not able to cover the 2.24 dB loss in cable, it shows that your coco does not have 8.5 dB gain.

However dont bother abiut this "big if". Your amplifier has gain of 13 to 18 dB which is more than enough to cover cable loss of 2.24 dB, as well as less than ideal gain of coco. Smile & wait for new amplifier.
 

jepolch

Active Member
RG59 has an attenuation of 8 dB/100ft.
28 ft of RG59 gives an attenuation of 8 x 28/100 = 2.24 dB, not a big deal, as you are using 8-element coco which can easily cover 2.24 dB loss in cable as it is supposed to have 8.5 dB gain if (and this is a big IF) the CoCo is:
(1) Perfectly Designed.
(2) Perfectly Built.

Since your Coco is not able to cover the 2.24 dB loss in cable, it shows that your coco does not have 8.5 dB gain.

However dont bother abiut this "big if". Your amplifier has gain of 13 to 18 dB which is more than enough to cover cable loss of 2.24 dB, as well as less than ideal gain of coco. Smile & wait for new amplifier.
I wish that was the end of the story. Being so disgusted with loss of coverage, I cut the poles down and brought the antenna back into the house. Now it was fed to the receiver with just three feet of RG6 cable. Still the reception was poor. So I took the antenna out of the PVC pipe, thinking maybe it was the problem, and connected the bare antenna directly to the receiver using just the short MCX to coax adapter (about 8 inches) and still the reception is not anywhere as good as it was prior to my starting this whole exercise. See my Before picture in post #418. I can't even get back to that level of coverage and that screen shot was taken when I was using the coco inside the house attached directly to the receiver. What can be wrong, sun spots? :confused:

As you say, I'll have the amp in a few days so I can start all over again.
 
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