@RIN67630:
Your statistics with J Pole antenna are great, congratulations!
What were your statistics with 1/4 λ groundplane antenna?
A comparison of two statistic will quantitatively highlight the difference of J Pole and 1/4 λ groundplane antennas.
Announcement
Collapse
No announcement yet.
3 EASY ANTENNAS FOR BEGINNERS
Collapse
X
-
Originally posted by SpaxmoidJAm View Postcareful this is turning into a not so easy antenna thread.
Forget amplifiers, forget expensive coax cables and connectors, adapters etc...
The trick is to use the short stock cable and place receiver and Pi close to the antenna.
I get ~280nM every day and my current antenna location is far from being perfect, it is still not above the roofes around.
T-EDLW40 Statistics (from an average day):
STATUS: Online CURRENT UPLOAD RATE: 0 KB/S FIRST SEEN ONLINE: 2016-01-03 22:59:14
LOCAL IP: N/A MAC ADDRESS: 00:00:00:00:00 COORDINATES: 51.3684,7.9404
UPTIME (AS % OF AVAILABLE TIME): 100% AIRCRAFT SEEN: 1,788 POSITIONS REPORTED: 84,496
MAXIMUM DISTANCE: 286nmLast edited by RIN67630; 2016-04-02, 03:01.
Leave a comment:
-
@RIN67630:
https://en.m.wikipedia.org/wiki/J-pole_antenna
http://www.hamradio.me/antennas/impr...e-super-j.html
Last edited by abcd567; 2016-03-31, 20:25.
Leave a comment:
-
Originally posted by RIN67630 View PostHas anyone got the dimensions of the Flightaware 1090MHz filter?
Could it be, that its metal can has intrinsically the correct dimension to work as a cantenna?
so the easiest way would have been just to stick a 68mm long piece of wire in its input and to wind 4 loops of cable at the other side to build a balun?
Please note that the coaxial antenna at right, although an old design, was not very popular as it did not have as good performance as other dipole designs. I realized that the narrow dia of copper pipe/tube has resulted in very narrow air gap between coax and tube, and this was the main reason of its poor performance. I then decided to use a much larger dia sleeve to enlarge the air gap, and this proved successful, and was birth of the Cantenna. I did try narrow dia sleeve made of 3/4 inch (20 mm) dia copper pipe, another with medium dia (54mm) drink can, and third with wide dia (68mm) Pepsi can. The 68mm dia can proved best, and 20mm dia pipe proved worst.
(English translation in red added by me)
Last edited by abcd567; 2016-03-29, 23:25.
Leave a comment:
-
Originally posted by abcd567 View PostThe trickiest thing in J-pole, Slim Jim and Franklin dipole with matching stub is the accurate placement of cable tap off on the stub. At Ghz frequencies, few mm away from optimum point, and the antenna transforms from "very good" to "poor".
DUMP1090-Antenna2.jpg
That one worked also pretty well, maybe the right point is around 9mm?
Anyhow these antennas are really easy to build and perform much better than the shortened stock whip.
Leave a comment:
-
Has anyone got the dimensions of the Flightaware 1090MHz filter?
Could it be, that its metal can has intrinsically the correct dimension to work as a cantenna?
so the easiest way would have been just to stick a 68mm long piece of wire in its input and to wind 4 loops of cable at the other side to build a balun?
Leave a comment:
-
Originally posted by jrf View PostLooking at the dimension calculation for the J-Pole and your picture: the feed point and spacing shall be 0.006 m = 6 mm. Did I misunder this or is your spacing bigger and the feed point in a different distance? As I read in another post it makes a huge difference if the feed point is just a little bit off the correct postion? Just asking because I might give it a try...Originally posted by RIN67630 View PostI have been using ~1,7mm Ø wire. The distance is to be measured from the metal surface to metal surface, not from center to center.
Additionally the formula ist valid for a rectangular J shape. The bend radius of the wire being quasi circular, the distances should approximately match.
Of course it could be optimized, but then you need a HF-sender and a SWR meter.
Please see my 2013 post here: http: //forum.flightradar24.com/threads/3831-best-antenna?p=43396&viewfull=1#post43396
1) It was made of core wire of RG6 coax, which has 1 mm dia (18 AWG).
2) The stubs were U shaped and not rectangular. I found the optimum location of coax tap-off point at 18 mm from tip of U.
3) Tried two matching stubs with different gaps between parallel wires of the stub, one with 10mm and other with 5mm gap. Found 5mm gap gave better results.
.
Leave a comment:
-
I have been using ~1,7mm Ø wire. The distance is to be measured from the metal surface to metal surface, not from center to center.
Additionally the formula ist valid for a rectangular J shape. The bend radius of the wire being quasi circular, the distances should approximately match.
Of course it could be optimized, but then you need a HF-sender and a SWR meter.Last edited by RIN67630; 2016-03-23, 10:48.
Leave a comment:
-
Originally posted by RIN67630 View Post
Leave a comment:
-
Originally posted by Sam26K View PostThey key to minimal loss between antenna and receiver is to put the USB stick as close to the antenna as possible.. USB sticks are cheap, good quality low loss coax is not so cheap. If you use a good quality USB cable you can easily have a run of 15' feet from the USB stick to the pi or computer without a problem with 5VDC source loss.
Otherwise if you have a long run of coax from the antenna to the receiver, an inline amplifier is the solution. A power supply is required. Did anyone come up with a good solution for the inline power amp? TIA!
If you want to build a cantenna, the easiest and far best way is to use only the F-pigtail and directly house the receiver stick inside the can.
You may use a 10m usb repeater cable that will not cost much more than the 10m F-cable that you won't need anyway.
Forget amplifiers, avoiding losses in HF lines is much more efficient!
Every additional HF connection weakens your signal, the receiver has enough gain anyway!
By the way: you should use a 10cm Ø stable food can. It can be fixed using cheap sewing pipe clamps.
You should also cover can and antenna with a matching plastic funnel, else water will accumulate onto the can. :-(Last edited by RIN67630; 2016-03-23, 08:06.
Leave a comment:
-
Originally posted by abcd567 View PostSince the antenna image does not say it is a jpole, there may or may not be a dc short. The best way is to check for short using multimeter. However there is no harm in installing a dc voltage blocker as a precaution.
Sent from my iPad using Tapatalk
Leave a comment:
-
Originally posted by andrewh_85 View PostI recently acquired a similar antenna from ebay, I am connecting with a bnc to f connector into my dongle giving me great coverage.
I also purchased a filter if I connected that will it help improve my signal?
[ATTACH=CONFIG]7214[/ATTACH]
[ATTACH=CONFIG]7215[/ATTACH]Originally posted by F-EGLF1 View PostWhat you picture is NOT a filter, it is an in-line amplifier, it will not do anything without a bias-t power injector and psu, and possibly a DC blocker depending on the antenna type you connect it to, if you just connect it as it is all it will do is block the signal and you will not receive any aircraft!
With the correct setup then it might help if your signals are low, see elsewhere in the very long antenna thread for more details.
Additionally I have just looked at the other picture you posted, you will almost certainly need a DC blocker with that antenna as it is probably a J-pole type.
Leave a comment:
-
Originally posted by F-EGLF1 View PostWhat you picture is NOT a filter, it is an in-line amplifier, it will not do anything without a bias-t power injector and psu, and possibly a DC blocker depending on the antenna type you connect it to, if you just connect it as it is all it will do is block the signal and you will not receive any aircraft!
With the correct setup then it might help if your signals are low, see elsewhere in the very long antenna thread for more details.
Additionally I have just looked at the other picture you posted, you will almost certainly need a DC blocker with that antenna as it is probably a J-pole type.
image.jpg
Leave a comment:
Leave a comment: