best antenna

[peterhr]

Alibaba is a Whole Sale Market place. The minimum quantities to be ordered runs in hundreds & thousands of pieces, directly from Manufacturers or their Sales Agents.
I have a bitter experience of ordering from eBay. I got one, no mention of DC Power Supply rating. Asked Seller, got no info. Used 14VDC, the standard Satellite LNB Voltage. Result same with & without Amplifier. Then I went to different stores in my neighborhood and in one of these stores, found RCA D903 for $4, and it worked like a Jinni.

The RCA branded one can be found in North America rare elsewhere, if we want stuff like that we dont have the stores to just go out and buy them, mostly on ebay they do have good pictures showing the voltage ratings. If the item doesnt work ebay/paypal has the grievence procedure and that is biased to giving you the money back.

Sent from my GT-P5110 using Tapatalk

[peterhr]

I finally got around to replacing the 12v PSU with a 15v one on the in line amp, here are two ADSB plots

ADSBscope1.gif
with 12v supply

ADSBscope2.gif
With 15v supply

the wedge to the west is due to the height of the neighbours roof (I could add another antenna mast section - but wind load is a concern)

antenna.JPG
This is the antenna (little expense has been spared on this, literally meant - the main costs were the mast and the pipe with the coco inside)

pi.jpg
and this is the un-attended feeder station (= I just leave it running weeks at a time without touching it)

[abcd567]

I made same antenna like you made it to see how far it works. With RadioShack in-line amplifier 950-2050Mhz...
But it didn't work well, the longest range was 70nm!
So what do you think, is it wrong with Amplifier or something else?
I live in an apartment 8th floor so that's high enough.

[ATTACH=CONFIG]2828[/ATTACH] [ATTACH=CONFIG]2829[/ATTACH]

Hi 747-8F
I have started testing different home-brew antennas with a very short piece of Cable (11 feet/3.5meters) between antenna & receiver to eliminate the effect of cable attenuation.
I ran/will run two set of test for each antenna type, one without Amplifier, other with Amplifier.

I have started testing the 1/2 wavelength dipole and Franklin dipole.
The first set of results (WITHOUT Amplifier) show 1/2 wavelength dipole gives far better result than the Franklin one.
The apparent reason seems high impedance (thousands of ohm) of Franklin compared to 75 ohm of 1/2 wave dipole, which perfectly matches with the cable & receiver impedance. Then why the results of Franklin with Amplifier were better cmpared to results of 1/2 wave dipole when I tested last month? And your results Franklin were bad when you tested last month? Is it because the RCA amplifier I used has the capability to match wide range of input impedance while the Radio Shack one is normal 75 ohm input/output type??? This is strange. I still cannot make out the reason of my previous good results of Franklin+Amplifier.

I will now again run the test WITH Amplifier, for 1/2 wavelength Dipole & Franklin, and compare with last month's results.

See results of this week's test for 1/2 wave dipole (NO amplifier) in pictures below: (Results for this week's Franklin are posted as separate post due to limitation on number of pictures per post)

DSC02788R2.jpg coverage-tiny-half-wave-No-Amplifier.jpg DSC02785R1.jpg DSC02784R.jpg

[abcd567]

Results for this week's test of Franklin halfwave-over-halfwave dipole with same setup as for 1/2 wave dipole in my today's previous post:

DSC02789R.jpg coverage-franklin.jpg

[Rooster]

@peterhr, what are you using for the power injector?

Sent from my ZX81

[abcd567]

I finally got around to replacing the 12v PSU with a 15v one on the in line amp, here are two ADSB plots

[ATTACH=CONFIG]2962[/ATTACH]
with 12v supply

[ATTACH=CONFIG]2963[/ATTACH]
With 15v supply

the wedge to the west is due to the height of the neighbours roof (I could add another antenna mast section - but wind load is a concern)

[ATTACH=CONFIG]2964[/ATTACH]
This is the antenna (little expense has been spared on this, literally meant - the main costs were the mast and the pipe with the coco inside)

[ATTACH=CONFIG]2965[/ATTACH]
and this is the un-attended feeder station (= I just leave it running weeks at a time without touching it)

So there is a noticeable improvement in Coverage when supply voltage changed from 12V DC to 15V DC... Gain has slightly increased....

Maybe I get a good gain because my power supply's actual (measured) voltage is 17V DC. The Power Supply is labelled as 14V DC, but measures 20VDC without load (open circuited, not connected to system), and 17V DC with load (i.e. amplifier connected and drawing current).....bad or no voltage regulater in my power supply, but blessing in disguise ... :-)

[abcd567]

The RCA branded one can be found in North America rare elsewhere, if we want stuff like that we dont have the stores to just go out and buy them, mostly on ebay they do have good pictures showing the voltage ratings. If the item doesnt work ebay/paypal has the grievence procedure and that is biased to giving you the money back.

Sent from my GT-P5110 using Tapatalk

Well, since it was very cheap ($4 +$2 shipment as it was un-branded), I did not bother for replacement or refund.
To ship-back the defective one will cost me shipment charges which were more than the cost of the item, plus to and fro shipment time.
Quicker & cheaper option was to get one of a good brand from local store.

[peterhr]

@peterhr, what are you using for the power injector?

Sent from my ZX81

Look for Power inserter on ebay.co.uk or amazon.co.uk - lots there...

What is more interesting is the regulators - search ebay for "5v regulator micro usb" - they allow you to run the Pi from the antenna amp power supply

So there is a noticeable improvement in Coverage when supply voltage changed from 12V DC to 15V DC... Gain has slightly increased....

That's a maybe ... weather conditions were different and it depends on what flights are buzzing to contribute to the graph.

[VE6CPP]

Birdie..what you are experiencing is known in the UHF/Micro-wave bands as 'Rain Scatter' ! Amateur Op's use it immensly on the 1-25Ghz Bands ! Wikipedia.. http://en.wikipedia.org/wiki/Radio_propagation
73 Good Prop !
Jerry
VE6CPP VE6Jee/p
F-CYQL1

I noticed whenever there is a thunderstorm, my coverage range increased.

Depending on the direction of the storm, some areas where they are blind spots to me, suddenly showed a unbelievable coverage.

[Rooster]

Id say the two coverage plots were more or less the same...
Cant find the injectors on ebay :-( guess ill diy one!

Sent from my ZX81

[peterhr]

Id say the two coverage plots were more or less the same...
Cant find the injectors on ebay :-( guess ill diy one!

Sent from my ZX81

Look for power inserter (looking for power injectors brings up Ethernet POE stuff) - I'd look for you but I don't know what country to look at...

ABSBscope3.gif
I left it running longer to catch more planes going past - this is about 4 hours worth

[abcd567]

Look for power inserter (looking for power injectors brings up Ethernet POE stuff) - I'd look for you but I don't know what country to look at...

[ATTACH=CONFIG]2975[/ATTACH]
I left it running longer to catch more planes going past - this is about 4 hours worth

I normally run the test for at least 24 hrs, and often 48 hrs, to be sure of results.

Sent from my N762 using Tapatalk 2

[abcd567]

... Cant find the injectors on ebay :-( guess ill diy one!

Sent from my ZX81

NOTE: These are search results only. I have never used any of these products/brands and do not know their quality/performance

Power Inserter from eBay UK:

1) http://www.ebay.co.uk/itm/Coaxial-DC...-/161121107526

2) http://www.ebay.co.uk/itm/Unbranded-...-/221318282241

3) http://www.ebay.co.uk/itm/A1330-LINE...-/140977355168

4) http://www.amazon.co.uk/N-A-SATELLIT...qid=1385363589

In-Line Amplifier from eBay UK (SEARCH "Signal Amplifier In-Line" on eBay to get a huge list):

1) http://www.ebay.co.uk/itm/IN-LINE-SI...S/161012784882

2) http://www.ebay.co.uk/itm/SAC-20dB-I...E/120963222204

3) http://www.ebay.co.uk/itm/Signal-Amp...e/390241293904

4) http://www.ebay.co.uk/itm/Satellite-...0/390705987031

[peterhr]

To those who have not bought stuff like this from ebay.co.uk before
* look at the item location ... if it's in the far east and 'free delivery', it will probably put on a slow boat from China and will usually take 3-6 weeks to arrive.
* watch out for carriage charges ... what appears to be the best priced item often isn't (but if carriage is extra, it will usually arrive faster)

I normally run the test for at least 24 hrs, and often 48 hrs, to be sure of results.

Ahh, Well - I don't leave the PC on 24/7 - too tight with the money to want to keep it powered, my feeder runs on a Raspberry Pi and that's what's left running.

[abcd567]

....T-EGBB19 : RTL2832U / R820T+ Raspberry Pi + Dump1090 with home brew collinear 7m above ground level....

@peterhr:
Do you like to share the details of your home-brew antenna, so that others can also built & try it?
If yes, it will be nice if you post some pictures (or sketches) of your home-brew antenna showing it's elements & element sizes.