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  • abcd567
    replied
    No need to cut the whip.
    Unscrew the whip and use a thin copper wire like one of 6 wires from a scrap network cable, or a thin steel tie wire like the one in first two photos below.

    Optimized Whip Steel Tie Wire.jpg




    Optimized Whip Steel Tie Wire-Dimensions.jpg


    Dimensions of Optimized Whip.png




    Use one of the many wires in a Scrap network cable





    category_5e_ethernet.jpg

    Last edited by abcd567; 2022-04-04, 04:03.

    Leave a comment:


  • Lufthansa
    replied
    20220403_180505.jpg


    Does anyone have an idea how I can shorten this antenna for 1090 MHz? Bought this antenna through Amazon a few years ago for some bucks, but it has performed / performs TERRIBLY....

    I don't know how to count the coils in the total length of the antenna (λ/4=6.88 cm or λ/2=13.75 cm). I've already read/searched a bit about coiled antennas/whips here in the forum, but didn't found a solution.

    I am grateful for any suggestion!
    Attached Files

    Leave a comment:


  • Bill@2020
    replied
    hello gentleman...
    i would like to show you my results of my development because of antennas. Years ago I started this development because of the unreliable ADS-B data during flying sharp u-turns, curves.
    The ads-b signal is generally vertical polarized. During flying curves the antenna is not vertical. Rod antennas and all other antennas on the market have all a vertical polarization.
    To avoid that problem I developed a new antenna which is very tiny, has a perfect pattern, can be used as sector antenna and no more filter is needed.
    attached I have a video which I made 2 days before ...the result was perfect and follows all simulated parameter ....

    Have fun

    Bill2002

    Sorry I have made comments in german....but you will understand :-/

    Leave a comment:


  • bg6snj
    replied
    Originally posted by abcd567 View Post
    Same wire data as above, simulated in software MMANA-GAL, gives Gain = 7.35 dBi, & very high SWR = 133 !!!!!!

    Which software to trust????

    Wire dia = 3mm
    Gap between stub wires =6 mm (center-to-center distance between stub wires = 1.5 mm + 6 mm + 1.5 mm = 9 mm)
    Optimum cable tap position = 45 mm from open end (or 69 mm -45 mm = 24 mm from shorted end)


    [ATTACH=CONFIG]4509[/ATTACH]. [ATTACH=CONFIG]4510[/ATTACH] . [ATTACH=CONFIG]4511[/ATTACH]

    I used 3.5mm diameter copper wire with 6mm spacing, built the Franklin antenna according to your size, and tested it with a 50ohm feeder. The resonance point is 1080MHz, and the SWR is as high as 3 at 1090.

    Can you tell me where there might be a problem?

    Leave a comment:


  • abcd567
    replied
    Originally posted by raptor22 View Post

    Do I need a filter?
    Here is my data capture record
    Screenshot 2021-09-17 195508.png
    Yes you do need a filter. Heavy mobile phone signal present in GSM850 band.

    Optional: You may conduct this scan also. It covers full band of DVB-T (24 Mhz to 1800 Mhz)

    ​​​​​​In thread "Do I Need a Filter":
    OPTION-4:
    DVB-T plugged into Windows Computer - Using GUI Spektrum.exe
    Last edited by abcd567; 2021-09-18, 01:13.

    Leave a comment:


  • raptor22
    replied
    Originally posted by Oblivian View Post
    Did you cut the top of the antenna down and put it on a can?

    I can't make that decision from this side of the world. All those commercial ones are far too expensive in our local value.
    But a DIY from wire to test may be a cheaper investment to try. Many use home-made and have good range.
    Do I need a filter?
    Here is my data capture record
    Screenshot 2021-09-17 195508.png

    Leave a comment:


  • abcd567
    replied
    raptor22:

    Please brows these two threads
    :


    3 EASY ANTENNAS FOR BEGINNERS



    QUICK SPIDER - No Soldering, No Connector



    .

    Leave a comment:


  • Oblivian
    replied
    Did you cut the top of the antenna down and put it on a can?

    I can't make that decision from this side of the world. All those commercial ones are far too expensive in our local value.
    But a DIY from wire to test may be a cheaper investment to try. Many use home-made and have good range.

    Leave a comment:


  • raptor22
    replied
    Originally posted by Oblivian View Post
    Known as MMCX or mini-sma
    https://en.wikipedia.org/wiki/MMCX_connector
    The antenna looks like it might be normal or RP-SMA (reverse pin)

    It would need a MMCX-SMA short length. Or some good coax and use a MMCX 'pigtail' between. Just remember each connector adds a little loss.
    Should I buy this antenna or DIY a new one myself?
    this is my theoretical range but I get only 32NM using the antenna which came with the dongle.
    WhatsApp Image 2021-09-16 at 11.56.11 AM.jpeg

    Leave a comment:


  • Oblivian
    replied
    Known as MMCX or mini-sma
    https://en.wikipedia.org/wiki/MMCX_connector
    The antenna looks like it might be normal or RP-SMA (reverse pin)

    It would need a MMCX-SMA short length. Or some good coax and use a MMCX 'pigtail' between. Just remember each connector adds a little loss.

    Leave a comment:


  • raptor22
    replied
    I am using this rtl-sdr dongle with Homeassitant. FR24 is installed in docker. Which port is this and which antenna I can use with it? How can I use the following antenna https://www.daraz.pk//products/i2274...L&urlFlag=trueb04d57081307991260a68871841afc95.jpg58e00ad19b6245c536f2d5bb1dbd46d5.jpg

    Leave a comment:


  • buenti
    replied
    My approach to building an antenna with a sma connector and copper wire:

    sma.pngthreaded.jpg
    bottem.jpg
    solder.jpgfranklin_spider.jpg
    Last edited by buenti; 2020-09-09, 22:58.

    Leave a comment:


  • abcd567
    replied
    Mag Mount Antenna’s Whip Replaced By V-Stub Wire Collinear

    Comparison of "V-Stub Wire Collinear Whip" with "52mm Optimized Whip"


    V_stub_wire_collinear_vs_52mm_whip-c.jpg


    Thin (0.5 mm dia) Steel Tie Wire used to make collinear whip with V-stub.
    Thin wire can easily be wrapped over threaded stud of magnetic base.

    Steel Tie Wire.jpg


    MEASURED PARAMETERS: V-Stub Collinear Whip


    SWR.jpg


    R_X_Z_SWR.jpg


    AIRCRAFTS SEEN & MESSAES RECEIVED (per sec)

    aircraft-messages.png


    .
    Last edited by abcd567; 2020-06-19, 17:16.

    Leave a comment:


  • abcd567
    replied
    Originally posted by Mephisto View Post

    Do you suggest to keep the plastic bottom of these antennas or to remove it before putting it on a metal surface?
    No need to remove plastic adhesive covering of the base. I have once removed the black plastic adhesive circle from base, but it did not give any improvement. Even with plastic in place, there is enough capacitive coupling between base metal and the food can.
    Last edited by abcd567; 2020-04-21, 19:02.

    Leave a comment:


  • Mephisto
    replied
    Originally posted by abcd567 View Post

    2. If you keep the magnetic base, and place it on a large metallic can, you get a good ground plane, and dont need to add radials. This is exactly what I have done. The Butter Cookies lid is providing a good ground plane, no need of radials.

    Do you suggest to keep the plastic bottom of these antennas or to remove it before putting it on a metal surface?

    Leave a comment:

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