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Thread: best antenna

  1. #1591
    Captain abcd567's Avatar
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    CRITICAL DEPENDENCE OF ANTENNA TUNING/SWR ON COIL DIMENSIONS
    I was modelling a 4-element dipole with single-turn coil. I used two options
    (1) for countries using Imperial/US system: use 3/4 inch dia PVC pipe as former to wind the coil.
    (1) for countries using metric system: use 25mm dia PVC pipe as former to wind the coil.

    The 3/4 inch PVC pipe has outer dia = 1.05 inch = 26.7mm
    The 25mm PVC pipe has outer dia = 25mm
    The difference between two dimeters is about 6.5%. I did not expect any difference in design if any of the two coil inner diameters are used.
    When I ran the simulation, the outer limbs for lowest SWR were:
    (1) 192mm in case of 26.7mm dia coil (3/4 inch pipe as coil former)
    (2) 206mm in case of 25mm dia coil (25mm pipe as coil former)

    Above shows how the tuning of antenna and achieving low SWR is critically dependent on coil dimensions.

    Please see the screenshots of two simulations below.

    CASE 1 - Coil inner diameter = 26.7mm (Coil wound over 3/4 inch PVC Pipe)

    15018570360_9bdc5ebf86_o.png , 15018464829_0e3a161f6e_o.png




    CASE 2 - Coil inner diameter = 25mm (Coil wound over 25mm PVC Pipe)


    15202198921_a4701b6719_o.png . 15205248285_64835ef9ca_o.png
    .
    Last edited by abcd567; 2014-09-28 at 08:48.

  2. #1592
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    Quote Originally Posted by abcd567 View Post
    Wow! 284 nm coverage!
    Can you please give some more details about your antenna, receiver, amplifier etc?
    Which software you have used to plot the range?
    Just for comparison here is my plot for today from my FR24 supplied box and antennae.
    image.jpgimage.jpg
    Ben.
    FR24 F-EGLF1, Blitzortung station 878, OGN Aldersht2, PilotAware PWAldersht, PlanePlotter M7.

  3. #1593
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    Quote Originally Posted by F-EGLF1 View Post
    Just for comparison here is my plot for today from my FR24 supplied box and antennae.
    image.jpgimage.jpg
    Ben.
    Mine one, almost 350 nm, near to overlap you being more than 1000 km apart.

    F-LEST1.jpg
    Northwest Spain: F-LECO1, F-LEST1

  4. #1594
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    Quote Originally Posted by F-EGLF1 View Post
    Just for comparison here is my plot for today from my FR24 supplied box and antennae.
    image.jpgimage.jpg
    Ben.
    Quote Originally Posted by Breitling View Post
    Mine one, almost 350 nm, near to overlap you being more than 1000 km apart.

    F-LEST1.jpg
    Wow! Both of you got excellent coverage, the magic of FR24 supplied professional equipment.

    With my "Home brew antenna+amplifier+50 ft/15m cheap RG6 Coax+DVB-T USB Dongle", my NORMAL maximum range is about 270 nm, OCCASSIONALLY jumping to 350nm under favourable weather & atmospheric conditions.
    Last edited by abcd567; 2014-09-12 at 00:11.

  5. #1595
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    Quote Originally Posted by abcd567 View Post
    Wow! Both of you got excellent coverage, the magic of FR24 supplied professional equipment.

    With my "Home brew antenna+amplifier+50 ft/15m cheap RG6 Coax+DVB-T USB Dongle", my NORMAL maximum range is about 270 nm, OCCASSIONALLY jumping to 350nm under favourable weather & atmospheric conditions.
    It is also very much down to location, I am on high ground with a slight hill to the south west, Breitling appears to be on a high point with completely unobstructed views 360-degrees around.
    Ben.
    FR24 F-EGLF1, Blitzortung station 878, OGN Aldersht2, PilotAware PWAldersht, PlanePlotter M7.

  6. #1596
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    It is accepted as essential to get the antenna clear of obstructions in all directions. I feel it is good to get a little more height if possible to get clear of clutter too where you may get reflected signals interfering with direct ones.

  7. #1597
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    Quote Originally Posted by peterhr View Post
    It is accepted as essential to get the antenna clear of obstructions in all directions. I feel it is good to get a little more height if possible to get clear of clutter too where you may get reflected signals interfering with direct ones.
    You are right. increasing antenna height improves both on obstructions & clutter.
    Since I cannot increase antenna height (live in an apartment), my only chance is that the city council decides to create a soccer field, park, community hall, and public library, acquiring the land by demolishing all high-rise buildings around my building
    Last edited by abcd567; 2014-09-12 at 14:30.

  8. #1598
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    Sleeved Dipole With Amplifier ..
    Antenna+Amplifier assembly will fit inside 1-1/4 inch or 1-1/2 inch PVC Pipe for Outdoor Mounting


    Amplifier Gain: 13-18 dB
    Coax Cable between antenna & receiver: 50 ft/15 m RG6, Cheap Quality.


    Step 1 of 3 - Design & Simulation





    Step 2 of 3 - Construction





    Step 3 of 3 - Trial Run 2 hrs

    Last edited by abcd567; 2014-09-12 at 16:41.

  9. #1599
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    In my last post above, I have used 3/4 inch copper water pipe, as the 1/2 inch & 3/4 inch sizes are most commonly available.
    However, the antenna gain and coverage increases with increase in copper pipe diameter.
    If larger size (1 inch or 1-1/4 inch or 1-1/2 inch) copper pipe is used, it will give better coverage, and the assembly will still fit inside a 1-1/2 or 2 inch PVC Pipe.

  10. #1600
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    Two types PVC pipe end caps, to protect antenna and amlifier inside the pipe, from rain water & moisture.

    The #1 end cap seems better for both upper & lower ends of pipe, as it is glued to the pipe by a special adhesive for pvc pipes & couplings. Once glued, the lower endcap will not be dislodge by downward pull of coax or weight of antenna+amplifier assembly.

    # 1 15219747735_540bf38607.jpg ......# 2 15033160628_e01028c355_b.jpg
    .
    Last edited by abcd567; 2014-09-16 at 15:27.

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