FlightAware Discussions

Antenna advice Discone Vs Collinear and some issues

Thanks for reading my first post.
I’ve recently put together a Pi 3B+ with a Prostick Plus to allow me to receive ADS-B. I was receiving up to 89 nm with a discone at 31M ASL on the rear of my house.

I added a 10 element collinear in the hope of receiving signals that bit further away, it has gone worse if anything, down to 79nm. This antenna is away from the discone at roughly the same height, give or take a few cm.

Please see the attached heatscan of the local radio environment, could somebody help me with them and advise if filters are required? I’ve run the gain optimisation script and it pointed me towards 44.5, duly set and running.
Any advice gratefully received. I’ve posted a second image below as being a new user I can only post one image at a time


Kev

Hi mate,
This is going to be somewhat tough to answer with the info you’ve provided so far, but I’ll take a stab to get the ball rolling (hopefully in the right direction):

First, as you probably realize already, the Discone as good as they can be for overall coverage will not be very good for ADSB in general - those things pick up about as much as possible, so the decoder will have a lot of noise to deal with for starters.

While your scans don’t show excessive noise (the Prostick Plus is already filtered), there could be some improvement on that end, but I’d like to focus more on the antenna in specific:

Can provide any other detail on this unit? Overall, my tests have proven that the FlightAware 26" antenna is probably the best bang for the buck (I’m not affiliated with FA, this is from my own comparisons by testing side by side and spending my own money and time doing so).

Before plunking money down on another filter, I think you’ll see more positive results with the FA antenna. That said, you could be an aerial guru with VNA in hand and have fashioned a fantastic collinear, so more information will be needed to assist further I think.

If you are already running a Discone, I can assume that you’re not a rookie when it comes to radio, so we’ll focus on more of the 1090Mhz stuff in specific I think to get started.

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Nitr0.

Thanks for the response. I bought the collinear from Broadsword Antennas as I couldn’t make it for what he was asking for the antenna. I have a bit of experience with antennas and have used VNA’s in the past.

What was I expecting? With the OK performance of the Discone I was hoping to hit over 100nm with the Collinear,. What I have noticed is that the gain from the antenna is working of sorts and the gain provided is lowering the lobes, allowing lover altitude aircraft to be seen vs Discone.

I’ll have a look at the FA antenna as I’m sure I can get better results, maybe raise it over the apex of the roof as it currently sits just below it.

Thanks also for your views on the heatscan, looking at others I did sort of grasp that my version looked alright with room for improvement but having someone familiar with them look at it is always a help.

Thanks

Kev

I took some money in my hand two weeks ago and got the Jetvision ADS-B Antenna. It outperforms my previous one by approx 10% which was already giving good reception. Antenna was built as a private project by an enthusiast.

If i am not wrong, FA is a customer of Jetvision, at least in Germany.
Using it with the blue FA pro plus stick seem to be the best value for me at my location. I am not using an additional filter so far.

@Terrierist:
The environment and the geographical situation has a high impact to the range. Friend of mine built a system on a church tower. He has a range of > 200 NM, but only in one direction. The other direction is blocked by the massive concrete of the tower walls. There is no way to bypass this as long as it’s in the way.

Also check heywhatsthat.com for your max range based on geographical environment. There’s a how to somewhere here in the forum.

@foxhunter

Thanks for the info, especially the hey what’s there link, very interesting and will need time to digest that.

I think the next step is to look at going back to basics and install some LMR 400 to allow testing of various antennas. I’ll then put up a strong pole and brackets, with the (bitty) knowledge I have of UHF/SHF I think that my antenna needs to be above roof apex level. Locally there is a bank call centre and an old Rolls Royce jet engine facility that may slightly impede comms to the west. Everything else seems ok.

@Nitr0

I’ve had a look at the FA antenna and it looks good quality, that could well be the way forward after some coketenna and dipole experiments.

Out of interest, do you have a link to the aerial from Broadsword?

What is the Maximum Range I can Get?

 

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@keithma

Only on Facebook if you use it, search Broadsword Antennas, not much technical info though unfortunately.

@abcd567
Thanks for this, my range is nothing like the orange ring, never mind the blue one

Yeah, I looked on Facebook but couldn’t see any products listed at all. I just wondered if it’s like the absolutely rubbish aerial I bought a couple of years ago from a UK supplier that worked worse than my home brew j-pole.

I was going to ask what kind of cable you are using and what sort of length it is.

@keithma

Well, I haven’t split it yet but I can see that coming.

15m RG 213, not ideal but would do as a test.

You are losing more than half your signal through that cable. So long as you use the same when testing between aerials, not a problem, but probably not a solid permanent solution as I think you already hinted at

The Jetvision that @foxhunter mentioned is highly regarded, unfortunately it was above my $50 threshold parameter for my test group:

I’d also be curious how the https://www.heywhatsthat.com/ link ends up for your location - that will give you a great idea on what to expect and most definitely worth looking into before spending more hard-earned money on your setup.

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That’s a recommendation which should be considered at the beginning to identify the max range. I’ve started with an easy DIY antenna, went over a handcrafted antenna from a guy with the equipment and now ended up with the Jetvision.

The range was quite the same for all three and it went to the max range i can get based on my location. Main difference is an improved message rate and more sensitive gain setting.

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@Nitr0 Great read that, enjoyed it. Thanks.

Have a look up the list as abcd567 has plotted it for me. The two rings and associated altitudes are far larger than anything I could possibly achieve as it stands.

The thing that really gets my goat is there are people with magmounts in windows getting further tracking than I am! :smiley:

Will have a look at the Jetvision, but I think it’s appx 3 times the price of the FA? Could I justify spending that for a small increase? Possibly not as the money could go to a new HF set I’m planning on buying in the future.

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Use the FA antenna, it’s just fine.

It will be much better than a discone for sure.
Rest of the money should go into filtering probably.

If you are a HAM and possibly transmitting from up there, that’s even more important.

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@wiedehopf Thanks for the advice, appreciated. I’ve come to the conclusion that I am going to invest in the following soon. 1) FA 66CM antenna on a 13 foot/4m pole, this will see the antenna about 5 feet /1.7m over the ridge tiles of the roof. 2) LMR 400 for this antenna 3) a suitable filter which I’ll take advice from the members on, please. I’m a little confused at which one to go for as I already have the filter in my Prostick plus, would another filter make that much difference or would it cause problems?