Whats next?!

[Anmer]

If you can place an antenna on the roof with unobstructed horizon I don't see why you need a directional yagi?

[Radio2.0]

that is the yagi antenna but it look like there is something wrong with?!
Why i get no more range?

[Anmer]

If the range has dropped using the same antenna it could be:

1. An antenna fault.

2. A bad connection.

3. A coax cable fault.

4, A receiver fault

5. A software issue

6. Or something else.

Try swapping the antenna if you have others.

[Radio2.0]

no i have only that. yesterday i order a new 900mhz Antenna and i try this. 
But how can i receive

more data?

[birdie]

Where are these yagis installed?

I could get a range of 250 nautical miles in all directions using a single, Mode-S antenna.

I got 329 nautical miles using Andy's Russian Antenna (shorter version). Not bad !

[Radio2.0]

How about your topography?
I am from Austria the Country of Mountain and Vales...

[G4UMW]

A Yagi antenna will give you directional gain but the vertical beamwidth can be very narrow. You may be missing traffic because it's effectively above the coverage of your antenna. Try angling your antenna slightly up and see if that makes any difference. Transponder signals are vertically polarised - your Yagi should be oriented so that the elements are vertical.

[Chris-G0WTZ]

Can I just comment A yagi at 1090 does not work effectively for adsb because as soon as the aircraft behind the beam goes above the horizontal beam width height it will get picked up by the dipole radiator. I would suggest a good Omni directional antenna of not too hi gain will yield better results.
I have been selling ADSB antennas for 10 years now and the only antennas I have ever had issues with is Yagis and it is because people do not understand how they work
A BS1105 at the same height as a yagi will give good all round coverage and see as far as a any yagi I have ever seen for 1090. The only time they are any good is for secular ground coverage at an airport
If you want to get around an issue of living in a flat have an omnidirectional antenna each side and bring the two coaxial cables into an antenna combiner
If cost is an issue take a look at the BBA that Amner has reviewed

:-)

[Radio2.0]

I would suggest a good Omni directional antenna of not too hi gain will yield better results.

I dont know anything about Radio and Frequency stuff but in fact with my Yagi I get the Airport Traffic. Without i see just ~ 1 - 3 Aircraft.

for secular ground coverage at an airport

I can agree with.

and bring the two coaxial cables into an antenna combiner

With a SDR Dongle is not necessary. The are so cheap and good its possible to connect each on a Antenna.

[Anmer]

I would suggest a good Omni directional antenna of not too hi gain will yield better results.

I dont know anything about Radio and Frequency stuff but in fact with my Yagi I get the Airport Traffic. Without i see just ~ 1 - 3 Aircraft.

Without knowing what you use instead, it's difficult to explain why you don't see as many aircraft with an omni-directional antenna.

[Radio2.0]

thats my antennas.
1) Yagi
2) Areal

[Attachment deleted by Admin to save file space]

[Anmer]

What make is the omni antenna and where is it located?

[Radio2.0]

What make is the omni antenna

i dont understand.

where is it located?

on the rooftop.

[Anmer]

What make is the omni antenna

i dont understand.

Where did you buy the antenna?  Is it a specialist 1090 MHz antenna?

[Radio2.0]

Yagi = http://www.amateur-radio-antenna.com/ism-aeronautical-antenna/secondary-radar-1090/antenna-secondary-radar-flu-sr-y13.php
Areal = http://www.dpdproductions.com/page_vhf_air.html#adsbout