Originally posted by SpaxmoidJAm
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A NEW EXPERIMENT - THE COILED WHIP
I have run a computer simulation of a coiled whip antenna based on design on following webpages:
1. http://martybugs.net/wireless/collinear.cgi
2. http://cheatthezone.tripod.com/wireless/colinear.html
Thanks to Dave of Plane Finder forum who built the antenna in above webpage.
The dimensions in mm in above pages were based on 2.4 GHz (Wireless LAN).
Dave changed dimensions according to 1090 MHz.
http://forum.planefinder.net/threads...age-6#post-464)
Later Dave made a trial run of new antenna & advised me the results: much inferior to his Franklin.
http://forum.planefinder.net/threads...age-7#post-476
I then ran computer simulation on software 4nec2.exe. The computer simulation results tallied with the trial run - poor: extremely high SWR (2,000). Gain is ok (4 dB) but nullified by very high SWR.
daves-coil-type-whip-wire-data.png
daves-coil-type-whip.png
I then changed the coil diameter to 22mm to make it's circumference 22 x pi = 22 x 3.14 = 68 mm = 1/4 wavelength at 1090 MHz. It did improve the SWR from 2,000 to 170.
coil+whip-sweep-varying coil dia.png
I then added a ground plane, consisting of 3 wires equally spaced (120 degrees) and connected to each other & to braid of coaxial cable. This brought down the SWR from a whooping 170 to mere 2.8, and increased Gain from 5 dB to 9.5 dB
Output of computer simulation on software 4nec2.exe are shown in screenshot below (SWR=2.8, Gain= 9.5 dB)
Whip+Coil+Ground Wires-R1.png
.Last edited by abcd567; 2014-03-23, 05:47.
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Originally posted by peterhr View PostHas anyone tried these, four of them should give 360 degree cover (just curious)
http://www.ebay.co.uk/itm/Outdoor-di...item2ed021e268
Sent from my N762 using Tapatalk 2
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Originally posted by peterhr View PostT-EGBB19 : RTL2832U / R820T+ Raspberry Pi + Dump1090 with Bulgarian collinear 8m above ground level
Stats for: 2014-03-17, Uptime (as % of available time): 100%, Aircraft seen: 1,003, Positions reported: 1,107,731, Maximum distance: 268nm (496km)
Are you using an in-Line Amplifier? RTL2832U / R820T USB Dongle normally does not give such a great range without an in-Line Amplifier, as its built-in pre-Amplifier is not as good as that of SBS, Radarbox, etc.
Your Bulgarian antenna seems good. Checked its specs, found as follows:
Omnidirectional antenna 1090 MHz ADS-B 6 dBi for SBS, Radarbox, microADSB-IP
Up to 250 NM range with straight view (attached to microADSB IP BULLION receiver)
N female type directly mounted connector
Perfect for use with SBS, Radarbox, microADSB
Frequency: 1090 MHz
Gain: 6dBi
Azimuth: 360 deg
Impedance: 50 Ohm
Max Power: 50 W
VSWR 1,5:1
Vertical polarization
Wind Survival: 125 km/h
Temperature range: -45 to 60 deg C
Length: 70cm
Weight: 540g
Conektor: N(f)Last edited by abcd567; 2014-03-29, 16:53.
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No amp, the distance is what fr24 reported in the stats on day
The antenna hahs an N to F adaptor, then the downfeed is RG6. At the other ens the rg6 has a tv aerial plug to suit the mcx adaptor for the mini dongle.
There are no cable joins / pigtails so no cable reflections
Sent from my GT-P5110 using TapatalkLast edited by peterhr; 2014-03-29, 17:04.
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Originally posted by peterhr View Post.......There are no cable joins / pigtails so no cable reflections.......
Furthermore you have impedance mismatch (Antenna 50 Ohms, RG6 & RTL2832U/R820T USB Receiver 75 Ohms).
Reflection at N-Connector.pngLast edited by abcd567; 2014-03-29, 17:58.
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Originally posted by peterhr View PostI have just one mismatch - at the antenna end, there is no cable between the adaptors and the antenna / dongle. The adapter at the antenna end means I could pop an amplifier in there really easily.
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Reflection Coefficient Γ = (Z1 - Z2) / (Z1 + Z2) = (75-50)/(75+50) = 0.2
VSWR = (1+Γ)/(1-Γ) = (1+0.2)/(1-0.2) = 1.5 : 1
Later Addition:
Don't get terrified by 1.5:1 VSWR ...
The Mismatch Loss in dB = -10 log(1 - Γ2) = -10 log (1-0.2 2) = -10 x -0.01773 = 0.1773 dB .... peanutsLast edited by abcd567; 2014-03-30, 04:44.
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Originally posted by abcd567 View PostHow do you get the report from FR24?
I am also feeding data to FR24 (T-CYYZ-9), but never got any report.
IMG_20140330_195454.jpgScreenshot_2014-03-30-19-49-30.jpgF-YSWG1 and T-YSWG2
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Originally posted by YSWG View PostClick on More. You need to be feeding with FR24 Linux uploader or FR24 FlightFeeder.
[ATTACH=CONFIG]3758[/ATTACH][ATTACH=CONFIG]3759[/ATTACH]For official support use Contact Form
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