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 Post subject: Month of testing ADS-B antennas: February
PostPosted: Tue Mar 07, 2017 2:03 pm 
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rtlsdr4everyone - FlightAware user avatar

Joined: Sat Feb 27, 2016 5:25 pm
Posts: 33
First, I'd like to thank FlightAware for the reference antena used and all other companies for equipment.
In a nutshell, I made a mount, connected four stations, then tested various homemade antennas against a FA antenna.

Comparisons here:

http://www.radioforeveryone.com/p/testi ... s-feb.html.

I've detailed every step of the way, if you have any comments, questions, request, something is not clear, want me to test one of your designs, or anything, don't hold yourself back.
Would love to hear from testers with more experience how to improve, if there's an antenna design I should try etc. Franklins and CoCos in the near future, and many more.
Thanks,
Akos


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 Post subject: Re: Month of testing ADS-B antennas: February
PostPosted: Tue Mar 07, 2017 3:47 pm 
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rwinterhoff - FlightAware user avatar

Joined: Tue Jan 10, 2006 5:00 pm
Posts: 33
Location: Central Florida KMCO
Did not see the gain settings for all the dongles used. Did the gain change with the FA Pro's etc?
Interesting article - Thanks


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 Post subject: Re: Month of testing ADS-B antennas: February
PostPosted: Tue Mar 07, 2017 5:15 pm 
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rtlsdr4everyone - FlightAware user avatar

Joined: Sat Feb 27, 2016 5:25 pm
Posts: 33
No gain adjustments, stock PiAware image - I've updated post to clarify this, thanks.
What really struck me was the fact that Pro Stick Plus had significantly better performance on a medium-gain antenna than with its own FA antenna. I get 25,000 reports normally with Fa antenna, so 36,000 was a surprise.


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 Post subject: Re: Month of testing ADS-B antennas: February
PostPosted: Tue Mar 07, 2017 7:15 pm 
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aldoir - FlightAware user avatar

Joined: Sat Oct 29, 2016 5:54 pm
Posts: 79
Location: Curitiba/Brazil
I understand an end user shouldn't buy an analyzer as it's more expensive than an antenna itself, but you as a tester/blogger should.

Some of the antennas you're trying requieres matching coils to work properly. For example a well matched 5/8 antenna will always have a higher gain (on one specific direction) than a 1/4, but on your tests the 5/8 has a poorer performance.

Most of the problems you had (bad contacts, water, etc) would be easily identified before losing a day of tests if you was using a test equipment

Your test environment is far from ideal. Some antennas are closer to concrete (metallic) structures than others

My suggestions

1) Build real antennas. Don't call a piece of unmatched wire a "5/8 antenna" because it's not a 5/8 antenna (requires test equipment)
2) Ensure your cables are well matched for every antenna (requires test equipment)
3) Make a proper mast. Every antenna should be in the same distance from surrounding structures. Each antenna should be at least 2 wave lengths from each other (1 wave length is ok)


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 Post subject: Re: Month of testing ADS-B antennas: February
PostPosted: Tue Mar 07, 2017 7:37 pm 
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abcd567 - FlightAware user avatar

Joined: Sat Feb 15, 2014 3:08 am
Posts: 1856
Location: Toronto CYYZ
I appreciate experiments and effort by Akos (rtlsdr4everyone). His drive to experiment and explore is great.

Aldoir's comments carry great weight and originate from his technical knowledge & vast experience. Impedance matching is vital for all types of antennas, except the naturally resonant 1/4 wavelength ground plane antennas (Spider & Cantenna) which have impedance between 50 and 75 ohms, and do not require any external matching equipment.

Antenna tuning equipment, such as antenna analyzer, are essential for a tester.

In spite of all shortcommings, Akos's effort are worth appreciating.


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 Post subject: Re: Month of testing ADS-B antennas: February
PostPosted: Tue Mar 07, 2017 10:18 pm 
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obj - FlightAware user avatar

Joined: Tue Sep 30, 2014 7:14 pm
Posts: 3193
rtlsdr4everyone wrote:
No gain adjustments, stock PiAware image - I've updated post to clarify this, thanks.
What really struck me was the fact that Pro Stick Plus had significantly better performance on a medium-gain antenna than with its own FA antenna. I get 25,000 reports normally with Fa antenna, so 36,000 was a surprise.

WIth a higher gain antenna the prostick frontend can get overloaded - there is a note on https://flightaware.com/adsb/prostick/ about reducing the dongle gain.


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 Post subject: Re: Month of testing ADS-B antennas: February
PostPosted: Tue Mar 07, 2017 11:12 pm 
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rtlsdr4everyone - FlightAware user avatar

Joined: Sat Feb 27, 2016 5:25 pm
Posts: 33
Thanks for suggestions, I strongly looked into a antenna tester, but blowing $150 on another piece of equipment is pointless for me, because 1)it would not be fully utilized, and 2) it's more fun (for me at least) to build an antenna and test it than measure it. Where's the fulfilled expectation if something works straight away?
For the end user, cantennas and spiders are the way to go as far as I can see at the moment, further tests will clarify whether errors in construction and various dimensions make a significant difference.
Re Aldoir's suggestions that antennas should be further apart: it has been suggested and I also thinking of a solution, but I have to balance ease of access with ideal location.


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 Post subject: Re: Month of testing ADS-B antennas: February
PostPosted: Wed Mar 08, 2017 4:12 pm 
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Nitr0 - FlightAware user avatar

Joined: Thu Apr 21, 2016 11:48 pm
Posts: 94
Well done Akos. There will be flaws in any study - that goes without saying - few of us have chambers to test in, if any.

For the average user, this should be a great article to read as it will definitely help a person that's sitting there with a stock MCX antenna in hand to see what they can make from objects laying around the house without spending a dime to greatly increase their performance. They most likely wouldn't have access to a meter either, so it's a totally mute point for this particular comparison and crowd it's directed towards.

My tests have also shown that the Cantenna (drink can) is probably the easiest and most responsive of the home-made crop of antenna - and it's quite resistant to user error since only the whip length needs special attention for the most part.

I wish I could keep a journal that well - I commend you for your time given and for publishing your results. Excited to see more.


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 Post subject: Re: Month of testing ADS-B antennas: February
PostPosted: Thu Mar 09, 2017 4:21 pm 
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rtlsdr4everyone - FlightAware user avatar

Joined: Sat Feb 27, 2016 5:25 pm
Posts: 33
I belive, from comments I've seen here and on the blog, that people have a misguided idea of what I'm doing:
Here's what I DO NOT TRY TO ACHIEVE:
- Find the best SWR ratio, or built an antenna rivalling a FA antenna.
- Perfect a hard to build antenna.
- Explore the difference between 3 or 10 mm gap in case of a Franklin. Abcd567's efforts are my bedside reading, kudos :-)

WHAT DRIVES ME:

Finding the easiest to build, minimum cost antenna with good performance.

WHY?

Look at FlightAware map, look at the dots. There's barely any in dark parts of the world.

PLEASE HELP ME

Imagine you have scrap materials, no SWR meter, no knowledge of radio, but you just bought a $8 dongle after saving up for it, and want ADS-B reception.
TRY antennas, TRY to build simple, TRY getting the best results.
I appreciate comments that my results are flawed, probably they are, not that I've seen a similar comparison backed up by hard data, not by theory concentrating on transmitting,. I just tested FA vs stock, and results are within 15% margin of error vs nitr0.
PLEASE HELP ME. Please build the easiest antenna you can think of, be it two spoons in a dipole config, or a monopole, or whatever.
Thanks for your compassion and sharing the same values I hold dear, namely helping others. Abcd567's cantenna was my inspiration for the Coketenna, spending 50c for a F female-female is easy for me and you and to citizens of the first world, but I've seen family providers fighting for a bottle of water in Africa, therefore I belive and will continue to struggle for simplicity.
Radio reception is for everyone.


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 Post subject: Re: Month of testing ADS-B antennas: February
PostPosted: Thu Mar 09, 2017 5:40 pm 
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abcd567 - FlightAware user avatar

Joined: Sat Feb 15, 2014 3:08 am
Posts: 1856
Location: Toronto CYYZ
rtlsdr4everyone wrote:
.......
WHAT DRIVES ME:
Finding the easiest to build, minimum cost antenna with good performance.

WHY?

Look at FlightAware map, look at the dots. There's barely any in dark parts of the world.

PLEASE HELP ME

Imagine you have scrap materials, no SWR meter, no knowledge of radio, but you just bought a $8 dongle after saving up for it, and want ADS-B reception.
TRY antennas, TRY to build simple, TRY getting the best results.
.......

Antennas for Hobbyists With Limited Money for the ADS-B Hobby:
Since I started this hobby in 2013, that was exactly my objective too. It resulted in following antennas at negligible cost and with materials readily available in most part of the world where one could affortd a DVB-T stick:

1) Year 2013 -Promoting DIY 1/4 wave dipole and Franklin made of core wire of commonly available and low cost RG6 coax.

2) Year 2013 - Promoting use of low cost Satellite amplifier instead of prevailing trend of using custom made costly LNA.

3) Year 2014 - Developing Cantenna which has almost zero cost, has good performance, and very easy to make right.

4) Year 2015 - Promoting optimization of stock whip by cutting it to size, and placing it on a can.

5) Year 2015 - Promoting use of DIY Spider with a low cost SO239/PL259 Connector.

Note: if one can get F-male twist-on connector, he can also easily get F female-female barrel connector from same shop. Cost wise, these are much cheaper than a DVB-T dongle and a computer (desktop/laptop/Ras Pi)

Antennas for Hobbyists Who Desire Best Performance:
However there are hobbyists who want better performance than achieveable from simple DIY antennas. They either have to purchase a commercial antenna like Flightaware antenna, or built and tune a "difficult to get right" antenna like coaxial collinear, wire collinear, stripline etc. All these require test equipment for tuning/impedance matching.


Last edited by abcd567 on Thu Mar 09, 2017 6:11 pm, edited 1 time in total.

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 Post subject: Re: Month of testing ADS-B antennas: February
PostPosted: Thu Mar 09, 2017 6:08 pm 
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rtlsdr4everyone - FlightAware user avatar

Joined: Sat Feb 27, 2016 5:25 pm
Posts: 33
@abcd567, I've read the majority of your posts on this forum and on others, and I linked them in the post, because I've learned a lot from your experiements and simulations on Franklins.
We're on the same page, and your contribution for discovering the cantenna is immeasurable.
Right now, I'm looking at minimising equipment cost, because the ultimate goal for me is getting the best performance for minimum money.
If you can test or simulate a drinks can cantenna (I call it Coketenna as it's easier to understand around the world, Coca-Cola is the 2nd best known world after OK) drinks cans are uniform around the world, 65 mm in europe, 68mm for 12 oz cans in N America as per my research) with various diameter tops and bottoms.
I ran a real life testing with a full-body Coketenna (bottom cut off) and it was worse than a 68.8 mm body, also, indoor tester had worse performance than me, so it's a gray area.
I ran a Coketenna with Pro Stick Plus and had less Totals vs FA plus Uputronics plus v.3, unsurprising.
I also ran 1/2 receiving elemwnt with 1/2 body, dismal.
I do not have the technical knowledge nor time with 4NEC2 to simulate, I'm also suspicious that longer braid off coax cable adds capacitance acting as ground to antenna.
Frankly, I have no clue why Coketenna works so well, so the next step is figuring out why, aldoir suggested that my location influences results, but I'm living here for years and tested ADS-B antennas in three continents.
Right now, I can't change my setup, so want to know how to improve, then if a theretical suggestion works out, I'll go to a hilltop and test again.
I just love antenna testing, like you, the joy :-) Thanks for helping, I appreciate any words from gurus!!!
I'm lucky as a poor tester that I can test antennas with the best equipment available, and I couldn't look in the mirror if I didn't do my very best to test every scenario.
So please, let me know. Thanks.


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 Post subject: Re: Month of testing ADS-B antennas: February
PostPosted: Thu Mar 09, 2017 6:26 pm 
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navzptc - FlightAware user avatar

Joined: Fri Feb 10, 2017 7:51 am
Posts: 10
Just keep doing what you do - I have been a Radio Amateur (Ham) for the last 32 years and have just started with this A/C plotting and am very interested to learn the in's/out's of how to get the best from it.
I have read your posts and been on your site and it has taught me a lot coming into this 'New Venture'.
I applaud you for what you have achieved with what you have, and always look forward to your new posts/blogs.
Thank you for your time that you spend trying to help others :D


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 Post subject: Re: Month of testing ADS-B antennas: February
PostPosted: Thu Mar 09, 2017 7:22 pm 
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rtlsdr4everyone - FlightAware user avatar

Joined: Sat Feb 27, 2016 5:25 pm
Posts: 33
Thanks navzptc,

Positive comments like yours give me the mental push to change antennas at close to midnight, I mean soaked as I have to climb out balancing on ledge. Just been in :-)
I love dissing comments, I got lots of them, but every single one gives me power. Power to go on, I'm occiasionally wrong, but then, the one single case when I'm right is worth it.
Edit: I'll test three of the best I came across, FA vs 1/4 over four 1/4 vs Coketanna during the weekend. I gotta go to a hilltop. Procedure is the same, WiFi access via smarthone with data, and we can argue which antenna is better, but on my holidays with me and the missus soaking feet in the sea, half-wave antenna, and we looked at streaks in the sky and we had fun knowing what line goes where.
I think, and then, I accept I can be wrong, that getting plus-minus 10 percent more in range or totals will not matter when knowing what line in the sky does what.
Fun factor, not performance, rules the day. You can't see a plane beyond 100 nm, easy with any antenna.


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 Post subject: Re: Month of testing ADS-B antennas: February
PostPosted: Thu Mar 09, 2017 8:14 pm 
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abcd567 - FlightAware user avatar

Joined: Sat Feb 15, 2014 3:08 am
Posts: 1856
Location: Toronto CYYZ
@Akos:

(1) Dont take my remarks negetively. These were for your guidance, not to critisize you or discourage you.

(2) When something is posted in a forum, the poster should be ready to recieve all sorts of responces: positive/encouraging, guiding, critisizing/discouraging. Dont get discouraged by criticism, try to learn from it.

(3) It is good to explore and experiment. Continue with your experiments.

HAPPY EXPERIMENTING!


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 Post subject: Re: Month of testing ADS-B antennas: February
PostPosted: Thu Mar 09, 2017 8:20 pm 
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rtlsdr4everyone - FlightAware user avatar

Joined: Sat Feb 27, 2016 5:25 pm
Posts: 33
@abcd567 Absolutely not, any comment is a good comment. I look at comments as an opportunity to learn something.There are lots of people who know much more than I do, and those people can help me, and the community eventually, to get better.
No man is an island, and the more I know the more I realizeI know nothing.
Thanks, but I gotta go, I work in 4 fours :-(


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 Post subject: Re: Month of testing ADS-B antennas: February
PostPosted: Thu Mar 09, 2017 11:50 pm 
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rfroemming - FlightAware user avatar

Joined: Mon Feb 27, 2017 1:32 pm
Posts: 6
Wow, lots of info there! Thanks for taking your valuable time to share to everyone.

I turned up my receiver late February. I had a rocky road working with a virtual machine, but after switching to a Pi, all is good.

The one thing I didn't have to adjust to get a good working system was my cantenna. It isn't the most beautiful thing, but wow, does it work good for all salvaged parts! 245 NM range on my first try! It is a almond can with a hole drilled in it, a female to female F connector, and a bare piece of the RG6 center copper wire. Your data confirms that I chose one of the best home made antennas one could make.

Thanks for the info!


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