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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Mon Jul 11, 2016 9:16 am 
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ehud42 - FlightAware user avatar

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abcd567 wrote:
@caius:
A cheap indoor-type mag-mount copy of Sandpiper / Radar Rama.
With 1 meter RG174 cable & MCX-Male connector which fits into DVB-T dongle directly
$3.66 (£2.55) + shipping $1.01 (£0.70)

It is so cheap, I have ordered it, just out of curiosity to see if it really is as good as claimed (gain 2.5 dBi, SWR <= 1.5).
Expected delivery: when Chinese sail-ship anchors at west coast of Canada :D

http://www.ebay.com/itm/201090043498
http://www.ebay.co.uk/itm/201090043498



@abcd567:

I grabbed one of these as well and concluded that is was a fairly inexpensive source of solderable coax with a nice connector on the end :roll:

I had the antenna ~0.5m up a plastic pole on top of my garage. Did ok picking up local planes, range was very low. Ended up cutting the antenna off and soldering the cable to a new Franklin I built on the weekend. That is doing not too bad so far. (http://flightaware.com/adsb/stats/user/ehud42)


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Mon Jul 11, 2016 2:43 pm 
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abcd567 - FlightAware user avatar

Joined: Sat Feb 15, 2014 3:08 am
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Location: Toronto CYYZ
@ehud42:
I also discovered the same thing. Please see this thread:

Trial Run Results for Three Types of Whip Antennas

Another related thread you may find interesting:

Trial Run Results for Four Sizes of Ground Planes
.


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Mon Jul 11, 2016 7:42 pm 
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spotterssol - FlightAware user avatar

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:D


Last edited by spotterssol on Thu Jul 28, 2016 2:52 pm, edited 1 time in total.

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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Thu Jul 21, 2016 10:32 am 
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cs777 - FlightAware user avatar

Joined: Wed Jul 20, 2016 11:02 pm
Posts: 34
Hi all,

New to the whole ADS-B tracking here. I've got myself set up with a raspberry pi and regular old DVB-T dongle. It's working well, but I'm only getting about 30NM-50NM coverage at the moment.

I'm looking at creating a Cantenna or Spider antenna. Which one do people generally get more range with? Also, for the Spider antenna, what gauge of copper wire to people use for the legs and whip?

Thanks :)


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Thu Jul 21, 2016 12:05 pm 
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boab - FlightAware user avatar

Joined: Tue Mar 22, 2016 12:28 pm
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Location: London, UK
The Cantenna has my vote, The wire diameter does not matter, but I used a paperclip which is nice and strong and can cope with any passing pigeon.
I have tried several commercial antenna and the Cantenna is superb value for money and a nice no risk starter.
One day I shall be brave and build a collinear ;-)

Location, and height (clear view of horizon), out weigh the antenna and everything else!


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Thu Jul 21, 2016 1:01 pm 
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cs777 - FlightAware user avatar

Joined: Wed Jul 20, 2016 11:02 pm
Posts: 34
boab wrote:
The Cantenna has my vote, The wire diameter does not matter, but I used a paperclip which is nice and strong and can cope with any passing pigeon.
I have tried several commercial antenna and the Cantenna is superb value for money and a nice no risk starter.
One day I shall be brave and build a collinear ;-)

Location, and height (clear view of horizon), out weigh the antenna and everything else!


Thank you :). Going to assemble one today. Does it matter what sort of can I use? I'm thinking about an empty soup can?

Out of curiosity, I see people showing their range on maps. How does one go about doing this?


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Thu Jul 21, 2016 3:52 pm 
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abcd567 - FlightAware user avatar

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Location: Toronto CYYZ
@cs777
I am using my retired RPi B+ for testing software. It is located in a room where signal is not as good as where my main receiver and Cantenna are located.

For my test receiver's antenna, I made a Cantenna with an un-cut food-can (easier, no cutting of cylinderical wall, only drilling a hole in the bottom).

The food can is 2-11/16 inches dia x 3 inches height (7 US fl. oz).
In metric units, it is about 68mm dia x 76mm height (205 mL). If measured with rims, it is about 70mm dia x 80 mm height.

Every antenna's performance heavily depends on its location. I therefore cannot say how the un-cut food-can Cantenna compares with optimally-cut drink-can Cantenna. Since the Cantenna is very tolerant to dimensional variations, I feel the difference will be slight.

This weekend I will replace the drink-can Cantenna of my main receiver by food-can Cantenna to find out the difference.

Image


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Sun Jul 31, 2016 8:09 am 
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volpoon - FlightAware user avatar

Joined: Sun Jun 26, 2016 3:49 am
Posts: 18
The earlier comments about the advisability of starting out with a simple home brew antenna design is of course correct, but it is not hard to make a vastly superior collinear out of TV or satellite coax by following the easy instructions shown in this video.

The main pitfall in this design is to make sure you have the correct velocity factor worked out by checking what kind of central insulator your coax has. Mine had a foam insulator so I used 98mm long elements. If it had been solid plastic insulator and not foam I would have needed 110mm. These given lengths are teh length of the uncut coax, not the connecting stubs of the central conductor.

I slid my eight element collinear (all sections simply taped together with insulating tape) into a length of cheap, black electrical conduit with a wine cork stuck in the top end to seal it, taped around the cork and around teh base of the antenna and poked it out of my roof. I regularly get 300 statute mile spots and many hundreds a day of spots over 250 miles.

https://flightaware.com/adsb/stats/user ... tats-27881

I am using the excellent Flight Aware dongle and filter with a short RF cable (about three meters) and a long USB lead. Both the Flight Aware filter/dongle and this antenna make a huge difference over my earlier R820 / 1/4 wave spider antennas. I tested the collinear mounted in the same position with the same length feeder against a carefully made spider antenna and I gained about a third more range.

Watch the video - it isn't rocket science. Good luck. This antenna including the plastic conduit tube to protect it from weather cost me about £3 in total.

https://www.youtube.com/watch?v=TkUYdCPFXXs


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Thu Aug 04, 2016 12:32 pm 
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abcd567 - FlightAware user avatar

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Location: Toronto CYYZ
@volpoon
Great! You are amongst the very few lucky ones who get their Coco right.
All Collinears (Coaxial, Wire, PCB etc) are easy to make, but hard to get right without:
(a) using correct VF
(b) precision of cutting & assembling
(c) proper (and costly) test equipment and
(d) technical know-how to use these equipment to tune an antenna.

Since the normal hobbyist lacks last two of these requirements (c & d), most end up in a poor collinear antenna (Coaxial, Wire, or PCB). Only a few lucky ones like you end up with a comparatively better one, a shot in dark which luckily hit the target board, but definitely not the bulls-eye.


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Thu Aug 04, 2016 4:21 pm 
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theresjam - FlightAware user avatar

Joined: Sat Feb 07, 2015 5:48 am
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ignore points c&d have a go. Whats the worse that can happen?


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Thu Aug 04, 2016 4:52 pm 
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abcd567 - FlightAware user avatar

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@theresjam
Worst which can happen is a lot of frustration when you try your new coco and find it performs much less than a 1/4 wavelength groundplane (Spider or Cantenna).

No harm in trying. If one is lucky, his coco will perform better than Spider. If unlucky, his frustration will be a lot less if one is aware that the chances of ending up with a poor coco are high.


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Sat Aug 06, 2016 7:58 am 
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volpoon - FlightAware user avatar

Joined: Sun Jun 26, 2016 3:49 am
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abcd567 wrote:
@theresjam
Worst which can happen is a lot of frustration when you try your new coco and find it performs much less than a 1/4 wavelength groundplane (Spider or Cantenna).

No harm in trying. If one is lucky, his coco will perform better than Spider. If unlucky, his frustration will be a lot less if one is aware that the chances of ending up with a poor coco are high.


I don't understand your scepticism. I've made a fair few antennas for ADS-B over the last four yeas since I started dabbling. They have all cost me pennies to make, some worked quite well and I could 'see' planes 200 miles off, some were really poor and couldn't 'see' more than about fifty or sixty miles. The video I referenced covers pretty much all you need to know to make a great success. A pal of mine a hundred miles away also made one - we both found stark improvements over our spiders. You are absolutely correct about getting Velocity Factor right, but this is usually available in the coax specs. And anyway - any antenna dabbler needs to consider velocity factor in putting up an antenna of whatever type, even if it is an HF dipole for the forty metre band. If the wire is covered by insulation, the VF will be different. It is frankly not true to say you NEED complex test equipment. Simple mental arithmetic and cable of a known VF is all that you need besides an accurate ruler and a sharp knife.

The point you made about accurate measurement and assembly applies equally to a 1/4 wave whip. This is especially true at these high UHF frequencies - HF - not so much, because minor errors then become a tiny fraction of a wavelength.

The signal collecting capacity of eight or twelve properly cut, half wave antennas stacked i correct phase is significantly more than a quarter wave - to say otherwise is frankly far from reality.. My collinear is an eight element one. It took me an hour to knock up including climbing about in the loft and poking it out of the roof. The coax was lying around as an off-cut so it cost nothing, the electrician's conduit tube cost £0.99 and is twice as long as it need have been and I am seeing about 1300 to 1500 planes a day at over 250 miles.

I am experimenting with two old net-book computers so I have two feed pages on Flight Aware. The current one is here:

https://flightaware.com/adsb/stats/user ... tats-26363

In a few days time from now, my page will be here:

https://flightaware.com/adsb/stats/user ... tats-27881

I would also say that this antenna was easier to make than my several spiders since it has no soldered joints. Correctly dimensioned collinear antennas will ALWAYS knock spots off a quarter wave whip.... It is a simple matter of physics. Look in any antenna hand book. The VF of the cable MUST be known or carefully estimated. Mine had a spongy central insulator core so I used a factor of 0.8. If it is hard polythene then use 0.66. The calculation is detailed in the video.


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Sat Aug 06, 2016 8:51 am 
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chrisjohnston50 - FlightAware user avatar

Joined: Fri Apr 01, 2016 3:29 am
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Location: Fort Lauderdale
I returned my 49", FlightAware antenna to Amazon because my stats started falling off vs the, shorter, 24" FA antenna.

Will attempt to construct an 8 segment col-linear as described in the YouTube video and report back.

Calling me a novice would be an understatement. :lol:


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Sat Aug 06, 2016 11:43 am 
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abcd567 - FlightAware user avatar

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If you look at the title of this thread, it says "...for Beginners", and that is why only 1/4 wave ground plane (Spider & Cantenna) were presented.

The 8 elements stacked vertically in a collinear fashion, will give higher gain and a better radiation curve, but can it be made successfully by a beginner without prior experience in making, tuning & using antennas? Chances of making a successful collinear (wire/coax/stripline) for a beginner are slim.

On the other hand for persons with prior experience of making & using antennas on HF, VHF & UHF, chances of success are much better.

The best strategy for a beginner is to start with a sure antenna like Spider & Cantenna. Once his system is up and running, he can navigate the troubled waters of collinears. One should first learn to walk before trying to run.

It is worth experimenting with coco, but with awareness that chances of success are not bright. This awareness will help in reducing frustration if failed.


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Sat Aug 06, 2016 8:02 pm 
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volpoon - FlightAware user avatar

Joined: Sun Jun 26, 2016 3:49 am
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Given that the segments are correctly measured, the main potential for failure is short circuit caused by whiskers of braid connecting across the ends of the elements. CAREFULLY inspect each end of every element for whiskers of fine copper braid before connecting them. They are very easy to miss, so don't rush the inspection. DON'T forget the tape across the ends to additionally assist in preventing a short at every joint. Push the elements together and if you have a continuity tester, or a simple multi meter, check each connection for continuity and shorts as you add each element, checking from the feeder end. The central core of the feeder will be connected to the end of each new element either at the braid OR the central core wire, alternating as you build it up with each new element. Likewise the screen of the feeder will also be connected to either the braid OR the core of each new element at its far end, but in the opposite phase to the centre of the feeder. Check each time that the feeder central core is NOT CONNECTED TO BOTH core AND braid on any element. The central conductor can only be connected EITHER to the core OR the braid. Same with the feeder braid. As you are building it up, if you find ANY connection to both on a particular element, you have a short and need to look at that last joint you made before you go further. If all is good, tape the new joint tightly and move on to the next. Give each joint a good wrapping of tape to ensure a long lasting antenna.

Eight elements will give a huge gain over a quarter wave. It will have sixteen times the signal collecting capacity because it is sixteen times as long.

Try it. All you have to lose is an hour and less than five dollars or about three UK pounds and only that much if you enclose it in electrical conduit (plastic obviously not metal). If you can fit a coaxial plug, and can use a ruler accurately, you can make an eight element collinear that will beat any other omni directional antenna by miles - probably by a hundred miles if you have a good site with all round to the horizon visibility.

Like any antenna, especially at these high UHF borderline microwave frequencies, it must be high and in the clear to give good range. If you have a good site, it will deliver the maximum theoretical range possible before the planes drop below the horizon.

Collinears not only have more signal collecting capacity than a quarter wave, but a much lower angle of radiation. Quarter wave antennas have their strongest radiation (and reception) at an angle bisecting the angle between the ground planes and the radiating element. A collinear looks straight out flat to the horizon, but will still pick up aircraft over flying your location.


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Sun Aug 07, 2016 12:16 am 
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abcd567 - FlightAware user avatar

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Location: Toronto CYYZ
@volpoon
I fully agree with you that collinears have higher gain and a better radiation pattern than a quarter wave ground plane.

I also agree with you that there is no harm in trying to make a DIY Coco. It costs almost nothing, and does not require too much effort.

The only point of disagreement is rate of success.
What percentage of Novice collinear makers succeed in making a collinear which is much better than a quarterwave groundplane?
My experiance tells "only few".


Image 1 of 3 - Simulation results of 8 element Coco
Image



Image 2 of 3 - Simulation results of Cantenna
Image



Image 3 of 3 - Simulation results of Spider
Image


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Mon Aug 08, 2016 4:43 am 
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volpoon - FlightAware user avatar

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The way settle the matter of how likely amateur antenna experimenters are to meet with success is for a few folk to have a go at building one. Otherwise we have a guy who say it is unlikely to work, and one who says if you take reasonable care it will work fine. Of course as any electronics kit supplier knows, give twenty men each a bag of components and a soldering iron and some will make grotesque mistakes in building the simplest kit. The warning to take care over whisker shorts at the ends of each element AND watching the video, AND taking proper account of the central insulation regarding velocity factor and element length makes success probable.

Image


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Sat Oct 22, 2016 4:09 am 
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biekerc - FlightAware user avatar

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I built a very clumsy (no soldering, screws to long, thin copper wire, not one leg really straight or of perfect length) spider antenna with a SO-239 as its base and used it to replace a 30cm coiled wire antenna.

To my surprise, it nevertheless works well with a Nooelec-TV dongle, where it increases the number of planes seen by 30% and more, and puts it almost on the same level as a Flightaware stick with filter and 30cm coiled wire antenna.

However, attached (almost directly) to the Flightaware stick with filter, the spider leads to no improvement at all, it actually seems leads to less planes seen?

Is there any conclusion to be drawn from this, apart from that I am not well suited to patiently building things out of copper wires? Do I have to change gain settings? Rebuild the antenna closer to configuration?


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Sat Oct 22, 2016 3:08 pm 
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abcd567 - FlightAware user avatar

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Location: Toronto CYYZ
@biekerc
What is your gain setting with
(1) FA stick+Filter+Coiled Antenna.
(2) FA stick+Filter+ Spider Antenna.


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Sun Oct 23, 2016 6:07 am 
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biekerc - FlightAware user avatar

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abcd567 wrote:
@biekerc
What is your gain setting with
(1) FA stick+Filter+Coiled Antenna.
(2) FA stick+Filter+ Spider Antenna.


(1) -10
(2) -10

So far I have left the gain settings unchanged.

The coiled antenna is supposed to work up to 862Mhz, I think.

It seems that having either the right antenna for 1090Mhz or having a receiver that amplifies and has a 1090Mhz filter leads to better results, but the combination of both has no further effect. Maybe I am already at the limit of what I can do from this location?

I'll try and see if a change in gain settings changes this.


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Sun Oct 23, 2016 11:52 am 
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abcd567 - FlightAware user avatar

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Location: Toronto CYYZ
biekerc wrote:
I built a very clumsy (no soldering, screws to long, thin copper wire, not one leg really straight or of perfect length) spider antenna with a SO-239 as its base and used it to replace a 30cm coiled wire antenna.
............

Spider need not be elegant looking like a fashion model.
As long as its wire lengths are fairly accurate (+/- 5%) and wires are fairly (not perfectly) straight, and angle of radial bent-down are nearly (not exactly) 45 degrees, it performs very good.

Spider is dimensionally very tolerant, and that is why it is a success even when built by a novice. Same applies to Cantenna.

Have you tried this Spider?:
QUICK SPIDER - No Soldering, No Connector


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Sun Oct 23, 2016 1:42 pm 
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biekerc - FlightAware user avatar

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abcd567 wrote:
biekerc wrote:
I built a very clumsy (no soldering, screws to long, thin copper wire, not one leg really straight or of perfect length) spider antenna with a SO-239 as its base and used it to replace a 30cm coiled wire antenna.
............

Spider need not be elegant looking like a fashion model.
As long as its wire lengths are fairly accurate (+/- 5%) and wires are fairly (not perfectly) straight, and angle of radial bent-down are nearly (not exactly) 45 degrees, it performs very good.

Spider is dimensionally very tolerant, and that is why it is a success even when built by a novice. Same applies to Cantenna.

Have you tried this Spider?:
QUICK SPIDER - No Soldering, No Connector



And no fashion model it is :)

But yes, in the end it is not that difficult to make, and it clearly has led to improved results with the standard RTL-dongle, so I guess it is worth the trouble.

BTW I tried changing the gain settings, but so far without any success.

Not yet, but I had seen that, it looks fairly easy to build and you basically just need a coax cable.


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Mon Oct 31, 2016 1:55 am 
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biekerc - FlightAware user avatar

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Posts: 39
A quick additional observation, I tried the spider + Pro Stick without the filter, my impression is that this has increased the maximum range, I am seeing planes that are further away that I did non see before.

The total number, however, still eems to a bit lower than the other combination of NooElec stick + spider and the Pro Stick + Filter + coiled antenna, but maybe that's just due to changes in traffic patterns.


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 Post subject: Re: 3 EASY ANTENNAS FOR BEGINNERS
PostPosted: Fri Nov 04, 2016 10:30 am 
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brianroyal - FlightAware user avatar

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abcd567 wrote:
EASY ANTENNA #2 : CANTENNA


Completed Cantenna

Designed & Built by Author of this post (abcd567)


Image

.


The best part about this antenna is it's deafness to frequencies that are out of band for ADSB. It's easy to make so that it's got a good SWR (about 1.5) at 1090 band and it all but completely attenuates anything below about 900. MUCH easier to build right than a Colinear Coaxial with better bandpass characteristics.

This helps to keep the receiver from dropping it's AGC when it gets bombarded with extraneous noise.

Image

EDIT: Can't recommend this design enough for a simple and reliable antenna that you WILL probably make correctly on the first try. If you're trying for maximum gain - Yeah, build a COCO. Just be prepared for a "learning experience" or two.
Build one of these FIRST so you have a decent antenna to fall back on while you troubleshoot your quad or eight element coco.


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 Post subject: Re: Three Easy DIY Antennas for Beginners
PostPosted: Sat Nov 05, 2016 11:45 am 
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keithma - FlightAware user avatar

Joined: Fri Nov 04, 2016 1:59 pm
Posts: 93
Location: JO01ou
I've got a half decent external aerial on the way which will go up nearly 30ft in the air but wanted something temporary just so I could get a feel for things.

So I knocked up a spider with six legs and hung it from my curtain rail with cable ties.

Image

It's working remarkably well considering it's thrown together and indoors. I've been a radio ham for over thirty years so I shouldn't be surprised when a resonant aerial works so well but these things still amaze me. I'm getting reports up to and slightly over 200 miles with that.


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