ADS-B DIY Antenna

[ab cd]

Here are results of my 3 antennas WITHOUT AMPLIFIER, and short (12 feet) Coax from antenna to Receiver.
As you can see, the Franklin & 5/8 wavelength Coil-Tuned are much inferior to Sleeved dipole when run WITHOUT AMPLIFIER.

This shows that:
(1) Half-wave Dipole is inherently tuned with SWR=1 if its two legs are cut at 69mm. This is very easy for any DIY hobbyist.
(2) Franklin & coil tuned (and coco also) require tuning which depends on dimensions & alignments. Little errors caused by DIY hobbyist throw them far away from optimum. These can be best made accurately only in Factory environment with all jigs, tools, templates & sophisticated test equipment.

Half wave Sleeved Dipole (Pepsi-can)


5/8 wavelength dipole with tuning/matching coils


4-element Franklin with Matching stub.

 

[ab cd]

Here comes sleeved Pepsi-Can dipole in an ENCLOSURE - It is very easy to make. Install it outdoors & enjoy.
(add amplifier if Coax is long)

The Antenna

The Test Setup, WITHOUT Amplifier & Short (12 ft) length of Coax from Antenna to receiver

The Coverage (WITHOUT AMPLIFIER)

HOW TO MAKE

(1) Dimension Diagram

(2) Collect the materials & tools

(3) Cut Pepsi-can to 69mm length, drill a hole in the bottom, fix a F-male-to-Female Solderable Panel type connector, Solder a 69mm whip to center of the connector.

(4) Drill hole in center of Jar's Lid, fix F-Female to Female connector. Also fix the mounting bracket to the Lid by two small nuts & bolts

(5) Screw Pepsi-can on the connector in the Jar's Lid.

(6) Screw-on the Jar on the Lid. Your Antenna is ready.

Enjoy ...

 

[ab cd]

If you have a long run of Coax, and want to add an amplifier to the Pepsi-can Sleeved Dipole, install it inside the enclosure beneath the Pepsi-can, like shown in sketch below (drawing is not to scale - lower part of amplifier may protrude outside the can, depending on make/model):

 

[ab cd]

I have tried a smaller diameter can.
The small can, same size as Redbull/220mL Pepsi (dia 2-1/4 inch = 58mm), showed slightly inferior to standard 330mL pepsi (dia 2-5/8 inch = 66mm) shown in pictures above.

I also tried a 3/4 inch (20mm) dia copper water pipe with end cap, results were substantially inferior.

From above it appears that the circular bottom of can provides an earth plane, while cylindrical wall of the can provides the lower 1/4 limb of the dipole.

HERE ARE THE ANTENNAS USED IN LAST WEEK's COMPARISION

 

[ab cd]

It is important that the Whip's FINISHED length is 69mm from the rim of connector, as shown in the drawing below.

If you have first cut the whip 69mm and then fixed it in position, it's FINISHED length will not be 69mm
It will be be less than 69mm if left connector is used, and more than 69mm if right connector is used.

Proper way is to first fix the whip in position, then measure and cut it to 69mm FINISHED length.

 

[ab cd]

Here is the concept put into practice.... sleeved dipole with amplifier...... Add an enclosure as described earlier

.

 

[ab cd]

....... Secondly I have built a CoCo antenna ........ This is the performance im getting ........ Im wondering why I get such good range to the east but every other direction is fairly mediocre? Granted I live near mountains but I would think planes flying high above the ocean shouldn't be an issue? Id really like to get 300Km all the way around.

It is because of terrain around you. Better/higher gain antenna cannot improve this limitation. Increasing your antenna height will give some increase in range, but can you raise your antenna say 200 ft above ground? Not a practical solution

There is a site http://www.heywhatsthat.com/.

Go there, then select the tab "New Panaorama" a new page will open. Enter your coordinates (longitude & Latitude), antenna height above ground, then click "submit request". It will take about a minute for site to generate & display the map for your area. On top right of this generated map there is a rectangle saying "Up in the Air". Click this rectangle, then zoom out. you will see two contour lines, orange (range for planes at 10,000 feet) & blue (range for planes at 30,000 feet).

I have done this exercise for you, using your Longitude & Latitude on the adsbScope range plot you have posted. The screenshot image is below. It more or less tallies with what you actually got.

Your antenna height was assumed 30 feet above ground

.

 

[plane-finder_user]

Do you use an Filter?

 

[ab cd]

Do you use an Filter?

No, I don't use any filter.
My antennas are made up of thin wire (central wire of RG6 coax - #18AWG/1 mm diameter). Thinner the wire, narrower is the bandwidth of antenna, and hence better is the rejection of adjuscent signals such as strong signals from nearby cell phone towers.

 

[ab cd]

NEW ANTENNA - THE COILED DIPOLE


STEP 1 - MODELLING & SIMULATION

STEP 2 - CONSTRUCTION

STEP 3 - TRIAL RUN
The the Camera Flash has created shadows of coils on the blinds, making coils look like double helix, with much more than actual number of turns.

.
The VRS Coverage.

12 hrs trial runWithout Amplifier. Length of Coax Cable between antenna & receiver = 12 ft (3.5 meters).

Range rings are 50 nautical miles apart

 

[plane-finder_user]

What is your range (in KM or NM please) ?
Do you ever compare a Cheap 900MHz Antenna to your?

 

[ab cd]

What is your range (in KM or NM please) ?
Do you ever compare a Cheap 900MHz Antenna to your?

(1) Normal range is 250 nm/470km, occassionally jumping to 300nm/560km under very favourable weather & atmospheric conditions.

(2) No, I never used any commercial antenna. All my antennas are made by me.

 

[ab cd]

What is your range (in KM or NM please) ?
Do you ever compare a Cheap 900MHz Antenna to your?

For range, please see the VRS range plot for coiled dipole, which I have posted above few minutes ago

 

[plane-finder_user]

can you look on my image please. I use an professional Yagi and for my opinion the range is to short.

 

[ab cd]

can you look on my image please. I use an professional Yagi and for my opinion the range is to short.

1) The range rings are not marked, with distance from receiver, on the image you have posted. How much is the distance of outermost ring (nm or km), and how much (nm or km) is the spacing between range rings?

2) Yagi is a highly directional, high gain antenna. In the direction it is pointed, it should give 450+ kms. If it is not, then possible reasons are:
(i) Yagi is designed for a frequency band far away from ads-b frequency 1090 Mhz.
(ii) The coaxial cable between antenna & receiver is long and/or lossy cheap qulity.
(iii) The terrain around your location is high and is blocking distant planes which are seen slightly above horizon.

To check the range limit imposed by your terrain, go to http://heywhatsthat.com. On the top left of page click tab "new panorama". A new page will open. On this page enter your longitude & latitude and antenna height above ground, and click "submit request" button. A new page with map showing your location will open. On top right of map click "up in the air" button and enter heights of planes 30,000 ft & 40,000, then click again "up in the air" button, and zoom out to cover lager area of the map, till you see 2 curves, orange & blue, showing your range limit imposed by your terrain....good luck.

 

[plane-finder_user]

the outher ring is 300nm i dont know how pp count.

2) The Yagi is a special 1090 from a german company.
I got it from my Hamradio Shop the owner say it the loss is less then nothing. 10m Cable ~40€

So i try it and the range shuld much higher its possible that DVB-T Dongle is to bad?

 

[ab cd]

Ch

the outher ring is 300nm i dont know how pp count.

2) The Yagi is a special 1090 from a german company.
I got it from my Hamradio Shop the owner say it the loss is less then nothing. 10m Cable ~40€

So i try it and the range shuld much higher its possible that DVB-T Dongle is to bad?

1) First of all check your terrain's limit using the link to "HeyWhatsThat.com" I have given in my previous post.

2) You require an omni directional antenna to pick signals from aircrafts from all directions. Yagi is a highly directional antenna, very sensetive in the direction it is pointing, and very poor for signals from all other directions.

3) Bad usb dongle may also be a reason. If you like, purchase another one to be sure. My first 2 dongles are from Nooelectric USA but made in china (each for $27 price+shipping)and 3rd one purchased from china ($9.75 including shipping). All 3 are good & perform equally good.

 

[plane-finder_user]

yes i check but its not realy korrect. I know i dont see some directions.
sure thats the reason i would take more Yagis.

 

[ab cd]

CANTENNA (CAN ANTENNA) TRIAL RUN

1 of 2 - Cantenna - No Amplifier

2 of 2 - Range of Cantenna.
No Amplifier, 12 ft/3.5m coaxial cable between antenna & receiver - 45 minutes trial run

Range Rings are 50 nautical miles apart
.

 

[ab cd]

DIPOLE LENGTH vs. RADIATION PATTERN