Antenna testers wanted


#1

Testing homebuilt antennas for the last three weeks versus an FA antenna, and had some surprising results. To verify data, Looking for volunteers who are willing to test antennas.
I’ve already posted results and setup in the following Facebook group : facebook.com/groups/476880835847288/
I’ll make results public, so if you wish to remain anonymous it’s OK.
Only requirement is to have a setup which is running for a while for verifyable results, or two stations. Only change the antenna, amplified or filtered or both makes no difference, I can replicate results.
I’ve built more than 30 antennas in February, so reaching out to the community - the more data, the better.
Please help my endeavor, my aim is to find an easy to build, cheap and good performing antenna, but because every location is different, more locations = better results.
Many thanks,

Akos


#2

Looks like a bait to increase your FB group, if you have something to share post here like everyone else does.


#3

I don’t have a facebook account. It won’t let me see anything unless I log in.

Oh well, onward…


#4

spammer Facebook


#5

It’s not my Facebook group, I’m only a member - seen the comment that some might not have a FB account, so here we go with Photobucket:

Against FlightAware antenna, unsurprisingly unavailable on Amazon:

amazon.com/gp/product/B00WZ … 134b246b89

Homebrew antenna:

Can external diameter 65mm, Height 69 mm, Wall thickness 0.12mm, no F connector used. I’ve seen the same design with F connector around (full creditcredit to abcd567 and others), but haven’t seen this particular execution e.g. braid pile-up for connection etc, no F female-female. If there’s an earlier manifestation I haven’t seen it, and will need to mention it, so chime in.

On a mount against a FA antenna, disregard the 1/4 ground planes, that’s not what’s interesting.

System margin of error 15% at three mount positions for comparative results, unamped setup:

My results are inconclusive and will need to rerun them later on (battling other issues at the moment), other local feeder’s two day’s data with Pro Stick and FA filter in indoor location shows the same antenna at 70% performance vs FA antenna.
Ask or bash away, if you’re really into antenna theory please include your estimate on how a full-wave dipole performed against FA antenna.


#6

Testing homebuilt antennas for the last three weeks versus an FA antenna, and had some surprising results. To verify data, Looking for volunteers who are willing to test antennas.

Recently I had some problems with FA antenna. During the winter storm last month it got water.

Red arrows point to places where water was accumulated.

In the mean time I made homebrew colinear.

After drying it up I was curious to compare FA antena to homebrew colinear.
Both antennas were hanging side by side on the window inside for some time
and showed similar performance with slight advantage in distance for homebuilt.

You can see that dongles are different, that might be also a factor for slight better performance for colinear.

Then I put FA antenna outside and replaced Nooelec dongle with RTL-SDR.

Both setups are now with RTL-SDR v.1 dongle but different batches.
Software is modesdeco both instances of it running on a desktop Dell.

Here are the results after several days of work

FA antena outside.

Homebuilt colinear behind the window.

The coverage with homebuilt antenna is narrower because of the place.
Both antennas are at equal height from the ground - about 30 meters.
They are 3 meters apart and the only difference is that one is behind the window

P.S. As for the FA antenna I must say that once it was dry it performs as before.


#7

Haven’t had luck with CoCo as I don’t know the exact velocity factor for my coax.
What are your element lengths?


#8

Haven’t had luck with CoCo as I don’t know the exact velocity factor for my coax.
What are your element lengths?

For the antenna design and construction credits go to Robert Nickels, W9RAN:
http://www.arrl.org/files/file/QST/This%20Month%20in%20QST/January%202014/VirtualRadarJan2013QST.pdf

I had some RG-6/U coax so just replicated what was in the article. Elements are ~114 mm.
Honestly didn’t expect such good result.


#9

Thanks, read that, already built 4 from RG-59B/U but without knowing the coax VF it’s trial nd error Have RG6 on hand, will build three, one with .83 like you, then try .85 and .81. Fingers crossed :slight_smile:


#10

I’m sorry, but like I have pointed out before, your testing methodology is flawed so your results are wrong.

Main points:

  1. The placement of your antennas is very biased against the collinear. A higher-gain antenna needs more free space around it to work as it should, than a low-gain antenna. Your placement is very lacking in free space, the antennas are too close together and too close to the wall/window.

  2. The measuring device (RTL stick) has a wide-open front end and is too sensitive to RF interference. When you increase the antenna gain, so does the noise levels, canceling out the benefits of a better signal.

So, the only thing you have proved is that in YOUR location, with YOUR local RF interference situation, without filtering, the higher gain antenna is a waste of money. It has NO relevance to the actual performance of the antennas, or any validity in other peoples location.

Get a good filter (not FA’s if you are in a GSM900 country), and put the collinear at least 1 meter from anything else, and you will see completely different results.

No info of any value will be gained from doing similar tests in other location, without any knowledge of the RF situation.

/M


#11

Thanks for the comments.

A higher-gain antenna needs more free space around it to work as it should, than a> low-gain antenna. Your placement is very lacking in free space, >the antennas are too close together and too close to the wall/window.
Any reference why the FA antenna needs more space around it and why antennas are too close together, and too close to the wall? Quite a few folks tape antennas to a window, or place them on a window ledge, where space around antenna is restricted. As I said, my results are inconclusive, I will test your suggestions later on.
2. The measuring device (RTL stick) has a wide-open front end and is too sensitive to RF interference. When you increase the antenna gain, so does >the noise levels, canceling out the benefits of a better signal.
That’s what people will have to live with without investing in a high-performance filter, or turning down gain in software. I’d say the vast majority of ADS-B enthusiasts use an RTL-SDR stick, so I’m using them as well.
I tried a cavity filter vs an Uputronics and a cavity filter did not improve my performance, full test on webpage.
So, the only thing you have proved is that in YOUR location, with YOUR local RF interference situation, without filtering, the higher gain antenna is a >waste of money.
I have not proved, nor try to prove anything - I consistently recommend the FA antenna and will continue to do so. Even my margin of error is 15 % between three mount positions with all else being as close to equal as possible.
or any validity in other peoples location.
Exactly the reason why I asked a fellow local enthusiast to test antennas, and why I posted results above. More tests = better reliability.
No info of any value will be gained from doing similar tests in other location, without any knowledge of the RF situation.
That’s why I’m publishing results here, and asking for input from others.

If you PM me I’ll be more than happy to send over a link to my testing diary, with all the data, polar plots and numerous images. In the meantime, could you test the antenna above and report back on comparative performance?

Thanks,

Akos


#12

As it pertains to Cantenna vs 26inch FlightAware antenna: I did my own comparison some months back - each rig with mirrored setup, only difference between the two was antenna. Both were on the roof, 1m apart:

First off some cheapy meter readings of each antenna:
FlightAware 26 Inch on Left, Cantenna on right respectively for all following images::
http://puush.hopto.me/Q4CF
http://puush.hopto.me/r7TU

Collectd graphs for the 24 hour period:
http://puush.hopto.me/cJfP

Statistics:
http://puush.hopto.me/7GIj

Finally polar plot (Light Grey = FlightAware Antenna):
http://puush.hopto.me/wC4u

These are raw figures for 24 hours. I would have suspected that the Cantenna would have performed a bit better based on the meter readings, but things change when the feedline is added, etc. Both setups were using FA Orange dongles, FA Filters, 25 feet RG-6 between antenna and filter. Both antenna were mounted at the exact same (base) height, but as we know, the FlightAware antenna has more radiant surface area exposed.

I have comparative tests for about 12-13 other readily available or made antenna using the same method, but in all honesty, I’m a little too lazy to compile and publish each result. I also know that some may chime in stating that the testing method is flawed, but can’t get much closer than 2 mirrored setups the way I see it to compare 2 different antenna. Tests performed under the same conditions at the same time for 24 hour periods.


#13

Many thanks for the above! I’d love to have a look at your results - seeing comparative figures vs FA would be great, raw data is OK.
Cantenna details? I’ve observed that the smallest difference between antennas or in feedline has an affect on performance. Right now, the cantenna seems to be the winner, but I’ll have to nail down ideal can parameters in real life.


#14

Thanks, read that, already built 4 from RG-59B/U but without knowing the coax VF it’s trial nd error Have RG6 on hand, will build three, one with .83 like you, then try .85 and .81. Fingers crossed :slight_smile:

I may suggest that since no soldering is involved you can play with the gap between elements instead making separate antennas with different elements length.


#15

Tried abcd’s design involving a fixed 114mm length and 66 mm adjustment section, but it’s easier for me to make 3 antennnas.


#16

[quote=“rtlsdr4everyone”]

It’s not my Facebook group, I’m only a member - seen the comment that some might not have a FB account, so here we go with Photobucket:

Against FlightAware antenna, unsurprisingly unavailable on Amazon:

amazon.com/gp/product/B00WZ … 134b246b89

Homebrew antenna:

On a mount against a FA antenna, disregard the 1/4 ground planes, that’s not what’s interesting.

(http://i1365.photobucket.com/albums/r741/aczera/Sat%2018%20feb%20results_zpsjlajf7k6.jpg)

This is your revolutionary antenna? I pass[/quote]


#17

I would be interested in testing the antenna for you. my email is kg5q@yahoo.com I have a flightaware feeder set up you can see it under my name or kg5q its in Show Low, AZ let me know if you have questions my phone is (moderated for privacy - send it in a PM…)