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1090Mhz atenna

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  • abcd567
    replied
    Home Brew Antenna -2

    My earlier home-brew antenna was really tiny & cute. It was 1/2 wavelength dipole consisting of two 1/4 wavelength arms, i.e a total of 2x6.8=13.6 cm, the tiniest antenna resonant at 1090 MHz. This antenna has a theoretical gain of 2 dBi.

    I have now built a "4-Element Franklin Co-Linear" dipole antenna with 5 dBi gain.
    It is a dipole, and has 2 arms, each arm is 2 x 1/2 wavelength tall.
    The total height of this dipole is therefore 2 x 2 x 1/2 wavelength = 2 x 2 x 1/2 x 27.2 cm = 54.4 cm.
    This antenna is 4 times taller than my tiny 1/2 wave dipole but has a gain of 5 dBi compared to 2 dBi of tiny dipole.

    In order to cover for attenuation of long coaxial cable, I have used 2 in-Line amplifiers (13-18 dB Gain each), costing $4 each amplifier.

    Please see attached pictures for my setup:
    Picture 1: DVB-T SDR USB Receiver connected to Desktop Computer.
    Picture 2: Power Injector (also called Bias-T) for injecting 15V DC in coaxial cable to power the in-Line Amplifiers.
    Picture 3: 4 x half-wave element Franklin Co-Linear Dipole Antenna.
    Picture 4: 1 x half-wave element basic Dipole Antenna.
    Picture 5: Schematic Diagram of the setup.


    DSC02555C.GIF DSC02543C.GIF DSC02576-R90c.jpg DSC02542C.GIF BIAS-T-02.jpg

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  • abcd567
    replied
    Home-brew Antenna

    DSC02542B.GIF DSC02543B.GIF
    See attached Images for My Home-Brew System of Antenna, 2x 18 dB inLine Amplifiers, Home-brew DC 15V Power Injector (Bias-T). My Maximum Range = 450 Kilometers with indoor antenna (simple quarter-wave dipole - 2 arms, 6.8 cm each) + 2 in-line amplifiers in cascade as shown in these pictures.

    Leave a comment:


  • Birdie
    replied
    Originally posted by Kpin View Post
    An active USB extention cable may be a good alternative to antenna cable. You can get a 50 ft. active cable for 30-50 USD or less. This means that instead of a long cable between the antenna and the USB dongle, you have the USB cable between the dongle and the computer. 'Active' means that there is a circute in the cable that will buste the signal.

    This means that you are also bringing the dongle outside and need to protect that too. You may go for a combination where you use a USB cable to bring the dongle up high inside the roof and then a shorter antenna cable to connect to the antenna on the outside.

    Put your dongle in one of this outdoor weather proof box.

    ClosedBox.jpg

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  • Kpin
    replied
    Originally posted by Oblivian View Post
    All cable has signal loss. Some more than others. The one you name will lose 4.42dB of signal every 25ft.

    If you have 25ft of cable to get it outside and on a roof that is 3dB of gain you have wasted. So if you have an external antenna of 9db on the end of it. it's effectiveness will be now less than 6 (as connectors also have a loss too)

    If you get high grade cable, this loss is a lot less. For instance LMR400 from memory is about .06dB/ft. Which means for that same 25ft length, you would only lose about 1.6dB
    An active USB extention cable may be a good alternative to antenna cable. You can get a 50 ft. active cable for 30-50 USD or less. This means that instead of a long cable between the antenna and the USB dongle, you have the USB cable between the dongle and the computer. 'Active' means that there is a circute in the cable that will buste the signal.

    This means that you are also bringing the dongle outside and need to protect that too. You may go for a combination where you use a USB cable to bring the dongle up high inside the roof and then a shorter antenna cable to connect to the antenna on the outside.

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  • Andrew Dale
    replied
    Ok thanks Oblivian and digiteyes, understood now.

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  • Oblivian
    replied
    All cable has signal loss. Some more than others. The one you name will lose 4.42dB of signal every 25ft.

    If you have 25ft of cable to get it outside and on a roof that is 3dB of gain you have wasted. So if you have an external antenna of 9db on the end of it. it's effectiveness will be now less than 6 (as connectors also have a loss too)

    If you get high grade cable, this loss is a lot less. For instance LMR400 from memory is about .06dB/ft. Which means for that same 25ft length, you would only lose about 1.6dB

    Leave a comment:


  • Andrew Dale
    replied
    Thanks for the info, not sure exactly what this all means, trying to though, just want to put the attenna outside so i get better reception, indoors is not good.

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  • digiteyes
    replied
    Originally posted by Oblivian View Post
    5dB loss /25 ft (rated 17@100ft) so if you have 20ft and a 3db antenna, you won't get any gain. Bare that in mind.
    It's pointless having a good antenna if you lose most of the signal in a poorly-rated cable.

    Which is exactly why I have recommended LMR400 cable.

    It's reasonably priced and has low loss @ 1.09GHz

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  • Oblivian
    replied
    5dB loss /25 ft (rated 17@100ft) so if you have 20ft and a 3db antenna, you won't get any gain. Bare that in mind.

    Leave a comment:


  • Andrew Dale
    replied
    Oblivian, yeah i hear ya and agree, im just excited about this FR24 and its software, i would like to be able to have good reception so i can feel i am positively contributing to the network. I know i am whether i see myself on the map i know that, i just want to make things better thats all. thanks for the info. Also i am not trying to be the primary upload source either. LOL In the radarview settings box what is the puropose of the load user data section, was just curious trying to figure it out.

    Leave a comment:


  • Andrew Dale
    replied
    Another question guys, i tried my small indoor attenna that came with the DVB-T stick outside in the backyard with my laptop, wow what a difference, i know getting a proper outdoor attenna will be just great but for now, if i got about 15 or 20ft of RG-179 cable and joined it to the existing attenna i have will that work temporarily?? I need about 15 or 20 ft to get outside and up near the roof. Of course i will seal the attenna with silicone first so incase it rains, i figure might as well use it outdoors until i can get a proper one because indoors it does not do well with reception. I was getting really good reception when the laptop was in our backyard, i had the attenna on the roof of our outdoor bar and it worked very well, was picking up quite a few AC with my radar tagged to them.

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  • Oblivian
    replied
    Originally posted by Andrew Dale View Post
    Thanks guys, i appreciate the info. i will decide what i am going to get and hopefully it will help me get on the radar map to say the least LOL Because i am getting destroyed by a few feeders nearby LOL
    Its not a popularity game. By them sending you a receiver you are feeding the data overall to improve quality regardless if you appear on the map as the uploader or not.

    You should only feel you need to add to it to increase your own interest rather than to try and be the primary upload source. Many of us run databases at home, and view local software plots rather than leave a FR24 window open all day to see ourselves.

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  • Andrew Dale
    replied
    Thanks guys, i appreciate the info. i will decide what i am going to get and hopefully it will help me get on the radar map to say the least LOL Because i am getting destroyed by a few feeders nearby LOL

    Leave a comment:


  • fungus
    replied
    Originally posted by speedbird1960 View Post
    You could have look at this one: http://1090mhz.com/
    Thanks Mike, I tried to locate that one earlier but it came up no longer available. Perhaps I just had the wrong website. (or my tired eyes, it's after midnoght here in oz).

    Regards,
    Gregg

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  • digiteyes
    replied
    This model is even better again than both the previous ones with respect to gain..... made in California.

    http://www.dpdproductions.com/page_vhf_air.html#adsbout

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