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  • Originally posted by peterhr View Post
    .....I'd dispute those:
    (1) when doing my initial set-up with the dongle and supplied antenna - I'd get maybe 50 miles range with it on the window board inside the window - opening the window, putting it on the cill outside, and closing the window on the wire increased range by about 50%.
    (2) raising the antenna has a huge influence mainly due to getting it above local stuff that blocks the signal and possibly in eliminating some local reflections .....
    As regards your point (1) I will try to find out the figures for attenuation (dB) caused by buildings as a whole, as well as attenuation figures (dB/meter thickness) for construction materials such as concrete, wood & glass. There has been lot of studies on this issue in connection with Cell/Mobile Phones & Wireless LAN. Once we have these figures, our discussions will be more quantitative, rather than qualitative as it is right now.

    As regards point (2), what you have said is exactly what I was trying to say. Antenna height sure helps in getting over local obstructions, but does NOT appreciably increase RANGE in non-obstructed directions. Therefore once the antenna is above the height of local obstructions, any more increase in height does not give any benefit, rather increases cost, effort, problems of wind & lightning.

    ......Raspberry pi might not be ideal, I believe Plane Plotter requires windows - FlightAware do have a Pi feeder for use on their own box - but last time I looked, they'd not released it as a separate software item. Maybe you'd be better off with an atom based single board computer or windows netbook.

    back to the original question:
    * Raspberry pi model B
    * Case for the same (this is really to protect the SD card slot since side pressure on the card can easily damage the slot and the SC card won't press against the spring contacts)
    * 5v 2A power supply with micro USB connector (you may have an blackberry / andriod phone charger that will work)
    * some 4Gb (or more) SD cards (one for use, others to try alternate configs)
    * It's helpful to have USB keyboard & mouse and an HDMI cable to connect to monitor or TV.
    * Some method to write images to SD card - does your PC have an SD card slot?

    Mostly for this - you'll run as light a weight debian as you can - the richer flavours like ubuntu may have drivers built in to drive the dongle as a TV receiver, which you have to disable to get rtl1090 / dump1090 to work. most of this is done on the command line - see the first few posts in http://forum.flightradar24.com/threa...e-to-feed-FR24 (probably best to continue this conversation there).......
    Thank you for your valuable advise. It is a great help to me, and possibly to many other forum members as well.
    Last edited by abcd567; 2014-03-16, 13:59.

    Comment


    • With the glass, it may be influenced by the coatings used to retain infrared


      Sent from my Nexus 4 using Tapatalk

      Comment


      • Originally posted by peterhr View Post
        With the glass, it may be influenced by the coatings used to retain infrared


        Sent from my Nexus 4 using Tapatalk
        I found some data for Building Entry Loss for UHF/Microwaves

        Building Penetration Loss-1

        SOURCE:
        Iternational Telecommunication Union (ITU)'s RECOMMENDATION ITU-R P.679-2, 1999


        Representative UHF signal attenuation observed within rooms located near an exterior wall in timber-framed private homes is summarized in Table 1. For interior rooms, 0.6 dB must be added to the tabulated values. For timber framed buildings the attenuation shows little variation with weather or path elevation angle but, as the table illustrates, there is a systematic variation with frequency, construction materials, insulation and position within the structure. Some aluminium-backed insulating and construction materials contribute up to 20 dB of loss.

        Note: TapaTalk does not display tables properly. Desktops & Laptops do.

        TABLE 1
        UHF signal attenuation (dB) through timber-framed buildings*

        Building condition Attenuation
        Exterior Insulation (non-metallic type) 860 MHz 1,550 MHz
        Wood siding Ceiling only 2.9 dB 5.0 dB
        Wood siding Ceiling and wall 4.5 dB 6.6 dB
        Brick Veneer Briques Ceiling only 4.1 dB 6.2 dB
        Brick Veneer Briques Ceiling and wall 5.7 dB 7.8 dB
        * The table is for rooms located near to the exterior wall; for interior rooms, 0.6 dB should be added.


        TABLE 2
        Signal distributions at the average position and best position within buildings
        (over the frequency range 700 to 1,800 MHz)

        Building number Construction Remarks Mean loss,
        Average position
        Mean loss,
        Best position
        1 Corner office, large windows, single-story building. Concrete block, plasterboard, double-glazing. Concrete roof on steel beams Line of Sight through window 7.9 dB 4.2 dB
        2 Small room with windows being 5/8 of exterior wall Line of Sight through window 9.1 dB 5.4 dB
        3 Corner foyer, large reflective glass door in half of one exterior wall. External walls concrete, internal walls plasterboard on metal frame Line of Sight through window 15.4 dB 9.7 dB
        4 Sheet metal shack with plywood interior. One small unscreened window on each of two sides, metal-covered door 9.7 dB 5.2 dB
        5 Two-story wood-side house, rockwool insulation (walls and attic); gypsum board, no metallic heat-shield. No metallic screens on windows. Wood shingled roof 9.0 dB 5.4 dB
        6 Empty sheet-metal mobile trailer home, metal frame windows with metal screens 24.9 dB 19.8 dB

        .
        Last edited by abcd567; 2014-03-17, 12:27.

        Comment


        • 3db = loss of 50% of the signal strength doesn't it?
          6db = 75% loss???

          Comment


          • Originally posted by peterhr View Post
            3db = loss of 50% of the signal strength doesn't it?
            6db = 75% loss???
            Yes every 3dB is half the signal lost.
            www.ADS-B.ca

            Comment


            • Originally posted by peterhr View Post
              3db = loss of 50% of the signal strength doesn't it?
              6db = 75% loss???
              Although the Tables in my last post prove that what I believed was wrong, I felt obliged to put these on forum, even if it caused me some embarrassment.

              Yes, you are right. Every 3dB loss halves the strength, so -3dB reduces signal to 1/2, -6dB reduces signal to 1/4, -9 dB reduces signal to 1/8 etc etc...

              I was astonished to see the loss figures in the Tables I have posted above. The loss figures are far too higher than I expected. I am now trying to dig out data from other sources to find out if the figures in the tables above are correct or not.
              Last edited by abcd567; 2014-03-16, 20:30.

              Comment


              • ...or you could walk around the house and see the range change as you move the antenna around.. I see it here, even in the attic and it is very noticeable.. Mind you, the signal seems strong enough to steal traffic from our F-'s but it could be much better if the antenna was outside

                Comment


                • .
                  Building Penetration Loss -2

                  SOURCE: Communications Research Centre, Industry Canada: Paper dated April 2011.

                  Apparently conflicting results have been reported in the literature concerning the dependence of building penetration loss on frequency. While several researchers have reported measurements indicating that building penetration loss decreases with increasing frequency in the VHF and UHF range, results by other researchers suggest the opposite, or that there is no significant dependence on frequency at all.

                  It has been noted that the frequency dependence of penetration loss appears to be strongly dependent on the type of building construction.

                  For residential buildings, which are typically constructed from non-metallic building materials such as wood, cinder block, brick veneer and glass, penetration loss has been found to be relatively low and to increase with increasing frequency. This observation is supported by results of laboratory measurements on a variety of common building materials, which show that, while propagation losses through most building materials are almost the same at 2.4 and 5 GHz, red brick and cinder block are notable exceptions; losses associated with these materials are 10.1 and 3.6 dB higher, respectively, at the higher frequency.

                  Industrial and commercial buildings, on the other hand, are often of steel-framed construction, and the corresponding predominant building materials are reinforced concrete, steel, and aluminum; loss through these materials is relatively much higher, and the dominant penetration mode is through slots such as windows and other frame openings, or even through grid openings in in steel-reinforced concrete slabs. Losses associated with propagation through slots tend to be strongly frequency-selective, and overall decrease with increasing frequency, as the slot dimensions become larger in terms of the wavelength.

                  TapaTalk does NOT display tables properly. Desktops & Laptops do.

                  Table 3: Estimates of building penetration loss at 700 and 2,500 MHz.
                  Building Type 700 MHz 2,500 MHz
                  Residential 4.6 dB 8.5 dB
                  Industrial/Commercial 14.5 dB 10.2 dB


                  Fig. 1: Measured building penetration loss versus frequency, for residential buildings.
                  building-penetration-loss-vs-frequency.png


                  .
                  Last edited by abcd567; 2014-03-17, 12:25.

                  Comment


                  • .
                    Building Penetration Loss -3

                    Source: COST 231 , 1999, a project of EUROCOST "The European Co-operative for Scientific and Technical research" or "Coopération européenne dans le domaine de la recherche Scientifique et Technique", which is a European Union Forum for cooperative scientific research.

                    TapaTalk does NOT display tables properly. Desktops & Laptops do.

                    Table 4: Transmission losses for external walls made of different materials in 1 - 2 Ghz frequency band
                    MATERIAL LOSS
                    Porus Concrete 6.5 dB
                    Reinforced Glass 8 dB
                    Concrete (30 cm) 9.5 dB
                    Thick Concrete Wall (25 cm) With Large Glazed Panes 11 dB
                    Thick Concrete Wall (25 cm) Without Glazed Panes 13 dB
                    Thick Wall (>20cm) 15 dB
                    Tile 23 dB
                    Last edited by abcd567; 2014-03-17, 12:26.

                    Comment


                    • Guys please help me, i made nearly four antennas still no luck check this 1.jpg2.jpg too much noise and very less range more or less same for all antennas and antenna is on my roof with clear view of sky and i'm getting tired doing antenna since two weeks continuesly please help me. why is that disturbance and if i set gains to auto im getting very weak signal and can only get when aircraft overhead. and if i reduced the gain manually again range is decreasing please please please help..
                      RTL SDR : T-VEVZ1

                      Comment


                      • you should get more than that with the little aerial supplied with the dongle - what does that give you if placed with a reasonable view of the sky?

                        (I'm wondering if you have a bad dongle)

                        also check you don't have a short circuit in the antenna feed by using the resistance test ranges on a multimeter.

                        Comment


                        • Originally posted by charan View Post
                          Guys please help me, i made nearly four antennas still no luck check this [ATTACH=CONFIG]3576[/ATTACH][ATTACH=CONFIG]3577[/ATTACH] too much noise and very less range more or less same for all antennas and antenna is on my roof with clear view of sky and i'm getting tired doing antenna since two weeks continuesly please help me. why is that disturbance and if i set gains to auto im getting very weak signal and can only get when aircraft overhead. and if i reduced the gain manually again range is decreasing please please please help..
                          Do you have any pictures of the antennas? Can you describe how they were made?

                          Comment


                          • Originally posted by charan View Post
                            Guys please help me, i made nearly four antennas still no luck check this [ATTACH=CONFIG]3576[/ATTACH][ATTACH=CONFIG]3577[/ATTACH] too much noise and very less range more or less same for all antennas and antenna is on my roof with clear view of sky and i'm getting tired doing antenna since two weeks continuesly please help me. why is that disturbance and if i set gains to auto im getting very weak signal and can only get when aircraft overhead. and if i reduced the gain manually again range is decreasing please please please help..
                            1. Check also if you have a mobile/cell phone antenna close to your house. Strong signals from mobile/cell phone transmitter neaby may also cause this problem.

                            2. What is your setup? Are you using an amplifier? Better post Camera Pictures / sketch showing your setup to help forum members to find out the problem.
                            Last edited by abcd567; 2014-03-17, 13:55.

                            Comment


                            • There are no shorts or anything DSCN1186.jpg .. and there is DSCN1176.jpg this attachment and another near dongle DSCN1174.jpg and the antenna is DSCN1183.jpgDSCN1184.jpg and the dongle is good because i have 2 dongles both are working excellent for satellite pictures and some vhf frequencies so there is no problem with dongle i guess.. what should i do ?
                              RTL SDR : T-VEVZ1

                              Comment


                              • ill post any other details if you need made that antenna based on this design 1090_ant_02.JPG and 123.jpg here is the waterfall ..
                                and also some times only icao code shows up and vanishes is this common? even there are no other planes in vicinity !
                                Last edited by charan; 2014-03-17, 14:11. Reason: added design picture
                                RTL SDR : T-VEVZ1

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