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  • #16
    Originally posted by mon View Post
    What data is this assumption based on?
    Based on this German Antenna:

    http://web1745.kostenlos-onlineshop....action=details

    AS-1090 Pre-Amplifier for 1090MHz
    Bild Vorverstärker AS-1090 AS-1090

    The AS-1090 is a pre amplifier designed specially for the Virtual Radar receivers SBS-3 and Radarbox. With such an amplifier the reception range of the SBS-3 is considerably extended. The AS-1090 can be used with any passive antenna like the GP-1090 or a discone antenna.

    An antenna pre-amp should always be mounted as close to the antenna as possible, not at the end of the (long) cable. If the pre-amp is used at the end of the cable (downstairs) it will still amplify the signal, but also the noise added by the cable. This results in a worse signal to noise ratio (SNR) and thereby in less effective decoding of signals. Another advantage of using the pre-amp right at the antenna is that you can use cheaper cable with higher attenuation for the long downlead to your shack.

    Technical Data:

    Frequencyrange 1030 - 1090MHz
    Gain 12dB
    Noise figure 0.9dB
    Supply voltage 12VDC over coax (remote)
    Power consumption 100mA
    Max. Input level +2dBm
    Connectors 2x N female
    Size 74 x 93 45 mm
    Weatherproof case for mast mount

    The AS-1090 includes all mounting hardware for mast mount. A Bias-T (DC injector) is not included.
    Order No.
    AS-1090 Pre amplifier 1090MHz 139.00 € Buy now
    Datasheet for pre amplifier AS-1090 (german, 320KB, PDF)
    F-WSSS1 - Cats refused to Pee & Pooh on RadarBox - Running a FR24 Receiver & DVB-T Dongle 24/7 to piss off The Chief Thief.

    Comment


    • #17
      I think he means, how did you come to the conclusion you will see microwave band from around the curves in the earth.
      Posts not to be taken as official support representation - Just a helpful uploader who tinkers

      Comment


      • #18
        Radio signal sometime behaves in strange manners. Possibly thru some reflections from the ionosphere.
        F-WSSS1 - Cats refused to Pee & Pooh on RadarBox - Running a FR24 Receiver & DVB-T Dongle 24/7 to piss off The Chief Thief.

        Comment


        • #19
          Originally posted by Birdie View Post
          Radio signal sometime behaves in strange manners. Possibly thru some reflections from the ionosphere.
          Then how does satellite communication work?

          Reflection on the ionosphere only occurs with much longer wavelengths and for troposcatter propagation the transmitter power of ADS-B stations is far too low. I guess the only reason for "strange" (i.e. unexpected) behavior in this case is the transmitter's altitude above ground level.

          Comment


          • #20
            Originally posted by mon View Post
            I guess the only reason for "strange" (i.e. unexpected) behavior in this case is the transmitter's altitude above ground level.
            Not necessarily, atmospheric ducting as described here (http://en.wikipedia.org/wiki/Radar_horizon) also affects the detection range otherwise my range for all aircraft at FL370 would be exactly the same which in practice is never the case, some days its 180nm, others it's 250nm.
            Michael
            Palmerston North,
            New Zealand
            ex-FR24 Feeder

            Comment


            • #21
              Originally posted by yurakm View Post
              Is it an import of the antenna (Radial 1090)? Specs and especially a graph looks too similar ...
              It's the same producer, but it may be some differences between the antennas. The "Russian" is 1,8m and the "German" is 1,5m.

              Comment


              • #22
                In RF, there's not absolute factors. It is important to say that different terrains might influence a lot your results. I see people here are talking mainly of vertical antennas with an ominidirectional pattern. (360° degree coverage in theory, that won't be exacly 100% true in real life but let's pretend it does to keep the analysis simple) You might notice that an omnidirectional antenna has a donut shape pattern for receiving. Whereas a high gain omnidirectional antenna is like that donut pattern that you sat on it and flattened it. In other words, it should give you more gain towards the horizon. If you are shooting for the airport (airplanes at ground location) and your location and airport is on the ground, a high gain antenna would probably be better. If you are on a mountain and the airport is on flat grounds but it might reverse if the airport is on a mountainous terrain and you are in flat lands. You can imagine different scenarios with what could happen with moving airplanes at the sky.

                This is too general, if you have the opportunity to test different antennas do it. A collinear antenna for ADS-B reception could bring very interesting results. Also, the antenna construction is important, you want it to withstand harsh weather like rain, winds or the solar radiation. Take that in account while choosing an antenna.

                Cheers,

                Luis

                Comment


                • #23
                  Just make of of these: http://x264.nl/dump/ads-b-antenna-gr...ane-proper.jpg
                  Vertical and radials 6.54cm long, calculated from: http://www.csgnetwork.com/antennagpcalc.html (angle of radials you need to play with a bit, for me 170-150 degrees from the vertical gives the best results.

                  That does this: http://x264.nl/dump/rtlsdr-mini-virt...1.1-record.jpg
                  (Using http://x264.nl/dump/rtlsdr_big-mini.jpg + adsb# sdrsharp.com)

                  Comment


                  • #24
                    Thats fine Jarod, but the original question from post no 1 was

                    "I am only listening for air traffic and were planes are going to and from"

                    I take this to mean vhf airband, not adsb

                    Mike

                    Comment


                    • #25
                      Oh then a discone antenna. I receive planes on the radar about 400-500km away.
                      Yes my antenna is higher than 50 meters off the ground.

                      This is what i listen to:
                      http://x264.nl/dump/schiphol_radio.txt

                      Comment


                      • #26
                        Good job mate, I built one of these

                        http://tech-software.net/1090_ant_02.JPG

                        I can receive the same as you. But the location is the deciding factor.
                        Mike in Tasmania, Aust

                        Comment


                        • #27
                          Originally posted by Mike View Post
                          It's the same producer, but it may be some differences between the antennas. The "Russian" is 1,8m and the "German" is 1,5m. ... I have tried about 15 ADS-B antennas from all around the world. And there is one antenna that is a lot better then all other antennas, it's this one: http://web1745.kostenlos-onlineshop....action=details You can double your coverage with this antenna compared to other ADS-B antennas.
                          You seem very anxious to promote THAT exact antenna. I can't understand why, except that you get some kind of commission or something. Also you never said anything about what antennas you actually tested, if anything...

                          As much as I like pre-fabricated antenna products where you don't have to solder and build the fkcing coax connectors, that is great, but the antenna you promote is seriously overpriced at 140 EUR, not to mention the 30 EUR shipping from Germany. Simply ridiculous. For that price, I can build 17 Antennas of very similar specifications!! That's right, a piece of coiled copper wire in a PVC tube + connector + a few meters of coax, goes for about 10 EUR here.

                          What happened to the joy of building your own antennas and learning something about it while doing it?

                          Originally posted by yurakm View Post
                          Is it an import of the antenna (Radial 1090)? Specs and especially a graph looks too similar ...
                          Semi-Commercial antennas are often direct rip-offs of amateur designs...

                          Originally posted by YWYY View Post
                          Good job mate, I built one of these http://tech-software.net/1090_ant_02.JPG I can receive the same as you. But the location is the deciding factor. Mike in Tasmania, Aust
                          Thanks for providing a good design. Here are a few others I found:

                          One of the more popular designs, probably also the one used in Mikes link above, but without the redundant "groundplane":
                          http://www.modesbeast.com/g7rgq.html
                          [EDIT]: On second thought, the ground plane is most definitely needed in that design. But if you're using PCB strip-line, there's no need, which may explain "what is inside" and the shorter dimensions of Mikes recommended antenna...


                          Similar...
                          http://www.tech-software.net/1090_ant_02.JPG

                          and another (co-linear):
                          http://www.multimode.fr/articles/rea...aire-1090-mhz/

                          An amazing compact J-pole with an optional 17 db pre-amp.
                          http://www.lll.lu/~edward/edward/ads...SBantenna.html

                          Or check out this extremely simple 240mm strip-line + 3m coax reaching 175 NM...
                          http://f5ann.pagesperso-orange.fr/An...MHz/index.html

                          So for those of you living in a not-so-rich country, pull out your soldering iron and save yourself >100 EUR!

                          Good Luck!
                          Last edited by E:V:A; 2013-03-12, 00:50.

                          Comment


                          • #28
                            Originally posted by E:V:A View Post
                            You seem very anxious to promote THAT exact antenna. I can't understand why, except that you get some kind of commission or something. Also you never said anything about what antennas you actually tested, if anything...

                            As much as I like pre-fabricated antenna products where you don't have to solder and build the fkcing coax connectors, that is great, but the antenna you promote is seriously overpriced at 140 EUR, not to mention the 30 EUR shipping from Germany. Simply ridiculous. For that price, I can build 17 Antennas of very similar specifications!! That's right, a piece of coiled copper wire in a PVC tube + connector + a few meters of coax, goes for about 10 EUR here.

                            What happened to the joy of building your own antennas and learning something about it while doing it?


                            Semi-Commercial antennas are often direct rip-offs of amateur designs...
                            Whilst I'm sure Mike is quite capable of defending himself, I wish some blokes could at least try to keep their comments civil on this forum. There is nothing in Mike's posts (or others for that matter) to suggest anything other than 'recommendations' for certain antennas and in Mikes case following years of experience installing various receiver systems all over the world, just as your 'recommendations' I guess may be of a similar nature. Or are they? Some of us dont have the expertise or capability to build our own antenna and appreciate recommendations for the pre-fab types (I'm disabled and cant make my own in any case). Some blokes will go for the 'home-made' variety and some take the other path- each to his own. There is no 'right' or 'wrong' in this case, just 'different' approaches. Any suggestion that there is some sort of kick-back for Mike 'promoting' a certain antenna seems to be plucked out of thin air and is nothing other than a disgusting slur. Sweeping comments such as "Semi-Commercial antennas are often direct rip-offs of amateur designs... " is somewhat extreme and unfounded and could also likely land yourself (and FR24) in hot water if not facing litigation.

                            As has been noted elsewhere on this thread (and others) and indeed I have found through my own experience is that there is more to this subject than simply the antenna construction itself. There is also a wide variety of opinions as to the 'best antenna.' I, and I'm sure many others, appreciate all feedback on various antenna types. I have both a Discone and a 1090SJ antenna (or did have prior to a storm wiping out the SJ) and have found that simply using a different pre-amp on either gives vastly different results. Then there's the question of cable which can also affect any outcomes. Certainly nobody has suggested that you cant 'build your own' antenna from what I've seen.

                            There's joy to be had in all aspects of this entire hobby as long as it's not ruined by unnecessary comments.

                            Regards,
                            Gregg
                            Last edited by fungus; 2013-03-12, 00:08.
                            YSSY2/T-YSSY4 [SBS-1 Basestation w/- SSE-1090 SJ Mk2 Antenna (Thanks Delcomp) ] [Uniden UBCD996T w/- 16 element Wideband Discone VHF/UHF Antenna, and tuned 108MHz-137MHz Airband Antenna] [Trialing a home-brew 1090MHz collinear antenna]

                            Comment


                            • #29
                              @Gregg:

                              Sorry, but I think you're overreacting. I just don't find anything uncivilized about that post. I was merely making a statement, questioning why we should listen to Mike's [antenna] recommendation without any supporting evidence or data, apart his "experience" here. I also question why this antenna has a cost of >17x the price of the individual components, as used in an equivalent design. (Especially since there's no telling what is inside that one.) I surely think this is of high interest to all of us, including Mike. I also gave several other "good" suggestions, which this thread is all about.

                              Comment


                              • #30
                                Originally posted by E:V:A View Post
                                @Gregg:

                                Sorry, but I think you're overreacting. I just don't find anything uncivilized about that post. I was merely making a statement, questioning why we should listen to Mike's [antenna] recommendation without any supporting evidence or data, apart his "experience" here. I also question why this antenna has a cost of >17x the price of the individual components, as used in an equivalent design. (Especially since there's no telling what is inside that one.) I surely think this is of high interest to all of us, including Mike. I also gave several other "good" suggestions, which this thread is all about.
                                I'll stand by my comments but leave Mike to deal with the issues you've raised with regard to him. I dont always agree with or see eye to eye with him on some issues and in fact we've had some quite 'robust' discussions but it's quite apparent that's not all you were implying. It's apparent you and I have a very different moral compass. I dont know how you can slur a bloke and the producers of pre-fabricated antennas and think that it's ok. Of course all input with regard to our set-ups and their components is of interest to many and should be encouraged and appreciated but needs to be done without any inflammatory commentary. If, in your opinion, a particular antenna is overpriced you (and anyone else for that matter) have a choice- dont buy it.

                                Gregg
                                Last edited by fungus; 2013-03-12, 02:39.
                                YSSY2/T-YSSY4 [SBS-1 Basestation w/- SSE-1090 SJ Mk2 Antenna (Thanks Delcomp) ] [Uniden UBCD996T w/- 16 element Wideband Discone VHF/UHF Antenna, and tuned 108MHz-137MHz Airband Antenna] [Trialing a home-brew 1090MHz collinear antenna]

                                Comment

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