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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Mon Dec 12, 2016 4:44 pm 
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keithma - FlightAware user avatar

Joined: Fri Nov 04, 2016 1:59 pm
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Location: JO01ou
I've actually got a reel of 16SWG tinned copper wire on the way so I'll have a go at that in the next week or so. I already have a reel of 18SWG enamelled copper wire but I really hate stripping the enamel off of it so I'll wait until the other stuff turns up just because I prefer it.

I know the 18SWG is a closer match to 16AWG but it'll be interesting to see how it performs.

/edit - Stuff it, I built one using the 18SWG enamelled copper wire because it's a new aerial to try and having got 35 years of aerial building and experimentation behind me, I wanted to do it!

Exactly as per the plan, double and triple checked everything.

In my back bedroom I've got a Pi3 with an FA Pro Stick Plus in the top with a quarter wave ground plane spider with eight radials. I removed the spider, plugged this aerial in and watched my aircraft count drop from 69 to 40 (it's late in the evening here, there's not much traffic). Plugged the spider back in and the count went back up.

I wish my VNA went up to 1GHz, it would make this aerial building lark so much easier. I'm normally doing stuff for HF.


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Mon Dec 12, 2016 5:52 pm 
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triggers - FlightAware user avatar

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Location: Oxfordshire, UK
@aldoir

Reading the url you posted above, is the author, John Huggins, saying that it doesn't matter how much wire is in the phasing coil but the distance between the "radiating" elements (53mm) is the important factor?


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Mon Dec 12, 2016 6:54 pm 
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@keithma,

Would you mind sharing a picture of your assembly? Specially the feed point? This is a very directional antenna (around 7dB for 4 elements, 6dB for 3), not the best for indoors thou

@triggers,

That's what I understood too, and both simulations on 4nec2 and pratical results says the same.

Here is my 3 elements I replaced by a 4 elements this weekend.

Image


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Tue Dec 13, 2016 1:21 am 
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keithma - FlightAware user avatar

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I should have quadruple checked everything - I did make a slight error in construction, I woke up this morning with the flash of realisation. I could try and modify what I've done but it'll be messy so I'm going to rebuild it later this week.


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Tue Dec 13, 2016 3:43 pm 
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triggers - FlightAware user avatar

Joined: Sun Dec 21, 2014 2:37 pm
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Location: Oxfordshire, UK
I made a new Collinear J pole today with 4 elements. It performed OK but still not as good as my 9 element CoCo.

I then made another 4 element one but with the elements 137.5mm rather than 132mm. Still kept the phasing stubs at 16 turns and 53mm height. All made out of 1mm copper wire. 137.5 is half wavelength I calculated :?:

Worked a treat !!

Image

The max range of the J pole is about 20nm less than the CoCo. 190nm vs 170nm

Tomorrow I'll remake the bottom end of the antenna with the quarter wave stub at 68mm and the three quarter stub at 206mm keeping the tap at 6mm.


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Tue Dec 13, 2016 9:14 pm 
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Nice! Could you please detail your setup? Stick, cable, amp if any


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Wed Dec 14, 2016 2:59 pm 
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triggers - FlightAware user avatar

Joined: Sun Dec 21, 2014 2:37 pm
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Location: Oxfordshire, UK
My test setup 26768 is:

FA Pro stick, 5 meters of unknown satellite coax. The antenna is in the roof void.

My live system 12366 is:

FA Pro stick, 2 meters of unknown satellite coax. The antenna is the FA one, outside on a pole approx 7 meters above ground level.

I live in a single storey house surrounded by trees so range in all directions apart from South is compromised.

The third system is at my brother's house in Farnborough. FA Pro stick, 2 meters of unknown satellite coax. The antenna is a home brew 12 element CoCo approx 10 meters above ground level.

[Edit} I built another collinear J pole today from thicker wire (1.8mm) to what I've calculated as quarter, half and 3 quarter wavelength. The tap is still at 6mm. Not looking as good as the one I made yesterday. I don't think this design is "easy" or for beginners.


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Wed Dec 14, 2016 5:29 pm 
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Running a VF=1 (137,5mm) too now.. let's how see it compares to the previous version.

I'm running a full 75ohms solution, 820T2 stick, sat amp, RG6 cable and it works ok.

My ProStick with full 50ohms feed does not work with this antenna, I'm start to think there is something wrong with my ProStick


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Fri Dec 16, 2016 7:14 am 
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aldoir - FlightAware user avatar

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Definitely the VF=1 (137mm elements) performs much better than the VF 0.97 (132mm).

I've updated my original post to reflect the new dimensions


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Fri Dec 16, 2016 9:54 pm 
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keithma - FlightAware user avatar

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I'm making a new spider over the weekend for my secondary receiver, I'll recalculate with a VF of 1 and make my elements the same length. I'll be using tinned copper wire so the velocity factor can't be anything else but 1.

In the new year, I'll buy a new VNA so I can actually test these aerials. My current one only goes up to 200MHx which although fine for my HF and VHF aerials, is useless for ADS-B at 1090MHz.

I feel naked without being able to actually check and test what I'm doing.


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Sat Jan 14, 2017 12:47 pm 
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myalias - FlightAware user avatar

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We need to get Andrew McNeal involved. He does a lot of microwave antennas, and has the equipment to optimize homemade antennas: https://www.youtube.com/watch?v=4XvbHeNsDas


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Fri Mar 03, 2017 12:22 am 
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inoc - FlightAware user avatar

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Hi abcd567,

If you would post the 4NEC or EZNEC wire tables for your cantenna and spider simulations it would be much appreciated.

Thanks


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Fri Mar 03, 2017 7:25 pm 
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JimMcConnell - FlightAware user avatar

Joined: Fri May 27, 2016 7:38 pm
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Been running PiAware 3.3.0 w/ProStick Pro, one with FA's older antenna 8 dBi (not their current 5dBi) about 9 miles from KDFW (Dallas, TX, USA) and the last 24 hours I hit 567K reports for 2575 aircraft. Antenna has good clear view of the ski (but still hiding from the HOA) Pleased with my first dive into ADS-B and Raspberry Pi. The intriguing thing to me, is my PiAware 3.3.0 w/ProStick Pro with a cut-to-length stock stub/whip antenna in Plant City, Florida, USA about 25 miles from a major airport, I got 371K reports for 2605 aircraft. The stub/whip is just stuck on a corner of a roof under a huge grandfather oak tree. My FA rank for the Plant City passed up the Dallas one today. Amazing.


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Sat Mar 04, 2017 5:17 pm 
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inoc wrote:
Hi abcd567,

If you would post the 4NEC or EZNEC wire tables for your cantenna and spider simulations it would be much appreciated.

Thanks

I have uploaded the 4NEC files to Dropbox. Download links are gien below:

Cantenna-68mm dia Can.nec

Spider-8 Legs-SO239 Connector.nec

.


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Sat Mar 04, 2017 6:57 pm 
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inoc - FlightAware user avatar

Joined: Sat Dec 18, 2010 11:00 am
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GREAT!, Thanks so much.

For all you do on these boards you should be getting paid a handsome salary!


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Thu Mar 09, 2017 11:37 am 
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navzptc - FlightAware user avatar

Joined: Fri Feb 10, 2017 7:51 am
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Thought I would make a 3D printable 8 leg spider using bits I had in the shack, and ended up with this which works well :D

Main element is a female SMA connector with CLF200 cable trimmed to size - this provides enough thread to hold ground plane washer/elements in position, and still allow male SMA to be fitted for cable run - Washer secures main element and radials to body.

Image

Image

Working well, and achieving 120+ miles with this in the attic :D


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Thu Mar 09, 2017 7:17 pm 
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@navzptc:
Your 3D printable Spider looks great. Nice built!


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Thu Mar 09, 2017 11:46 pm 
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inoc - FlightAware user avatar

Joined: Sat Dec 18, 2010 11:00 am
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You might try the legs at a 30 degree angle instead of 45, I think the impedance will come closer to 50 ohms and the VSWR will improve somewhat.


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Fri Mar 10, 2017 5:31 am 
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inoc wrote:
You might try the legs at a 30 degree angle instead of 45, I think the impedance will come closer to 50 ohms and the VSWR will improve somewhat.


Thanks for the tip - will give that a try :)


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Sun Apr 02, 2017 11:34 pm 
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AlpineMeadows - FlightAware user avatar

Joined: Tue Mar 21, 2017 12:07 am
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Got my SMA to F adapters in the mail so I built a cantenna tonight. Right now the location is where I had my un-trimmed RTL-SDR antenna (on the window sill) except I used double sided tape and taped the can to the middle of the window. Hoping for better stats tomorrow.

Once I get enough free time I'll put it on the roof.


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Mon Apr 03, 2017 11:10 am 
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windigofer - FlightAware user avatar

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navzptc wrote:
inoc wrote:
You might try the legs at a 30 degree angle instead of 45, I think the impedance will come closer to 50 ohms and the VSWR will improve somewhat.


Thanks for the tip - will give that a try :)


Keep us updated!

Also, once you've determined whether 30 degree or 45 degree angle legs work better, will you be sharing the 3D print pattern for the enclosure for those of us with 3d printers (say, somewhere like Thingiverse or similarly)? Those of us with access to 3D priinters (or who own our own) would probably like to try this out ourselves :D


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Mon Apr 03, 2017 6:18 pm 
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navzptc - FlightAware user avatar

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Quote:
Also, once you've determined whether 30 degree or 45 degree angle legs work better, will you be sharing the 3D print pattern for the enclosure for those of us with 3d printers (say, somewhere like Thingiverse or similarly)? Those of us with access to 3D priinters (or who own our own) would probably like to try this out ourselves :D


To be fair, can't say I have noticed any difference - an analyser would show you if it did, but don't have one!

Here are Dropbox links to the files - 123D so you can play with it, and STL to print as shown.

https://www.dropbox.com/s/j0h400vqr51lt ... 123dx?dl=0

https://www.dropbox.com/s/k5b4gssd2vqbb ... a.stl?dl=0


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Fri Apr 07, 2017 12:46 am 
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AlpineMeadows - FlightAware user avatar

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AlpineMeadows wrote:
Got my SMA to F adapters in the mail so I built a cantenna tonight. Right now the location is where I had my un-trimmed RTL-SDR antenna (on the window sill) except I used double sided tape and taped the can to the middle of the window. Hoping for better stats tomorrow.

Once I get enough free time I'll put it on the roof.


Compared to what I had before (RTL-SDR mag antenna untrimmed on window sill), my cantenna double sided taped to the inside of my window is a much better performer. Was topping out at about 70-75K hits/day, now hitting ~ 130K per day.

Time to put it outside! However I'd like to enclose it to protect it from water.

Question for the group - at what point does a plastic enclosure affect the performance? If I put it in a piece of 4" PVC drain pipe with end caps, will the PVC affect the antenna RF performance?


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Fri Apr 07, 2017 4:22 am 
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AlpineMeadows wrote:
Time to put it outside! However I'd like to enclose it to protect it from water.

Question for the group - at what point does a plastic enclosure affect the performance? If I put it in a piece of 4" PVC drain pipe with end caps, will the PVC affect the antenna RF performance?

1090 Mhz is microwave. PVC Drain pipe is generally made of such quality of PVC which absorbs microwaves. Pigments like black or brown increase absorption. White PVC is generally less absorbent.

You can easily test whether or not the PVC pipe you want to use absorbs microwaves. Put a small piece of PVC drain pipe in a microwave oven and run the oven for say one or two minutes and touch the pipe. If it is warm or hot, it absorbs microwave, and will sure attenuate ads-b signal. Do not forget to put a cup of water in microwave oven with the piece of pvc to prevent damage to your microwave oven.

The very first enclosure of the very first Cantenna:
https://forum.flightradar24.com/threads ... #post55629


A cantenna installed outdoors without enclosure. For enclosureless installation, better apply self bonding tape at coax's F connector, and some sealant like epoxy where whip enters F-barrel connector, and spray paint the cantenna.
https://forum.flightradar24.com/threads ... #post55687

.
.


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Fri Apr 07, 2017 1:29 pm 
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AlpineMeadows - FlightAware user avatar

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abcd567 wrote:
1090 Mhz is microwave. PVC Drain pipe is generally made of such quality of PVC which absorbs microwaves. Pigments like black or brown increase absorption. White PVC is generally less absorbent.

Thanks. I'll give your microwave suggestion a try. Will also try and compare 1 day to another with the PVC pipe as well as the microwave test at 2.45Ghz might not be applicable at 1.09Ghz. The PVC I was going to use is the thin white stuff used for landscape drainage/French drains - thin stuff.


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