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  • #1531
    .........And here is the Range of my Tiny Tot (half wavelength) antenna +AMPLIFIER
    Compare with post #1524 for range without Amplifier. See how the range has increased drastically by use of Amplifier

    1 of 2 - Half wavelength+AMPLIFIER



    2 of 2 - Range of Half wavelength antenna + AMPLIFIER - 2 hrs run

    Comment

    • #1532
      Originally posted by YWYY View Post
      This is the shorter one

      The computer simulation of your antenna (without heat shrink tube).

      Last edited by abcd567; 2014-08-25, 03:00.

      Comment

      • #1533
        What antenna software do you use, that's pretty cool
        Mike

        ps I see you are modelling in "free space" .You will get more accurate radiation patterns over real ground, which effects the reflection upwards
        Last edited by YWYY; 2014-08-25, 11:30.

        Comment

        • #1534
          Originally posted by YWYY View Post
          What antenna software do you use, that's pretty cool
          Mike

          ps I see you are modelling in "free space" .You will get more accurate radiation patterns over real ground, which effects the reflection upwards
          (1) For antenna modelling, I use 4nec2 software (available free of cost from http://www.qsl.net/4nec2/).

          (2) If the antenna is less than few wavelengths above ground, using natural ground gives more accurate results. In case of ADS-B 1090 MHz, the wavelength is very short (0.275 meters / 10.8 inches), and antenna is normally installed several tens of wavelengths above ground (20 to 30 ft above ground = 22 to 33 wavelengths), In this case using free space is more appropriate.

          Comment

          • #1535
            @peterhr:

            If used without amplifier, Cantenna (4.8 dBi) gives much better range than 1/2 wavelength dipole (2.2 dBi) due to higher gain.

            When used with amplifier, both give more or less same range, as amplifier Gain (13-18 dB) + it's AGC cover for low gain of 1/2 wavelength Dipole.

            I am waiting for your trial run result of Amplified 1/2 wavelength Dipole installed at roof/mast, and connected by coax to receiver down in your room.

            Comment

            • #1536
              Originally posted by abcd567 View Post
              @peterhr:

              If used without amplifier, Cantenna (4.8 dBi) gives much better range than 1/2 wavelength dipole (2.2 dBi) due to higher gain.

              When used with amplifier, both give more or less same range, as amplifier Gain (13-18 dB) + it's AGC cover for low gain of 1/2 wavelength Dipole.

              I am waiting for your trial run result of Amplified 1/2 wavelength Dipole installed at roof/mast, and connected by coax to receiver down in your room.
              The antenna is made - used hot melt glue to fix / waterproof the join on the dipole - need some decent weather to get on the roof to rig it up (not sure how far I can get it up due to available coax length)

              Comment

              • #1537
                Originally posted by peterhr View Post
                The antenna is made - used hot melt glue to fix / waterproof the join on the dipole - need some decent weather to get on the roof to rig it up (not sure how far I can get it up due to available coax length)
                If you post photos of antenna, amplifier, & mounting bracket, it will be a very good visual guide for all forum members on waterproofing the antenna & amplifier.

                Comment

                • #1538
                  Hi I have downloaded 4nec2, will have a play. Any chance I can grab that model you did of my antenna. Email provided below.
                  Mike

                  newmail4@internode.on.net

                  Comment

                  • #1539
                    you will need some patience with that software theres a little bit of a learning curve.
                    T-EGLF8

                    Comment

                    • #1540
                      Yes it seems very complicated, I normally use MMANA
                      I found a collinear on the web somewhere designed in MMANA - see below, just copy this text and paste into a text file.
                      Rename to ...ADSB.maa and open with MMANA

                      Code:
                      adsb-1090.maa
*
1090.0
***Wires***
31
0.0,	0.0,	0.0,	0.069,	0.0,	0.0,	5.000e-04,	-1
0.0,	0.0,	0.0,	0.0,	0.069,	0.0,	5.000e-04,	-1
0.0,	0.0,	0.0,	-0.069,	0.0,	0.0,	5.000e-04,	-1
0.0,	0.0,	0.0,	0.0,	-0.069,	0.0,	5.000e-04,	-1
0.0,	0.0,	0.0,	0.0,	0.0,	0.1376,	5.000e-04,	-1
0.0,	0.0,	0.1376,	0.00176,	-0.00424,	0.137,	5.000e-04,	-1
0.00176,	-0.00424,	0.137,	0.006,	-0.006,	0.138,	5.000e-04,	-1
0.006,	-0.006,	0.138,	0.01024,	-0.00424,	0.139,	5.000e-04,	-1
0.01024,	-0.00424,	0.139,	0.012,	0.0,	0.14,	5.000e-04,	-1
0.012,	0.0,	0.14,	0.01024,	0.00424,	0.141,	5.000e-04,	-1
0.01024,	0.00424,	0.141,	0.006,	0.006,	0.142,	5.000e-04,	-1
0.006,	0.006,	0.142,	0.00176,	0.00424,	0.143,	5.000e-04,	-1
0.00176,	0.00424,	0.143,	0.0,	0.0,	0.144,	5.000e-04,	-1
0.0,	0.0,	0.144,	0.00176,	-0.00424,	0.145,	5.000e-04,	-1
0.00176,	-0.00424,	0.145,	0.006,	-0.006,	0.146,	5.000e-04,	-1
0.006,	-0.006,	0.146,	0.01024,	-0.00424,	0.147,	5.000e-04,	-1
0.01024,	-0.00424,	0.147,	0.012,	0.0,	0.1473,	5.000e-04,	-1
0.012,	0.0,	0.1473,	0.012,	0.0,	0.3537,	5.000e-04,	-1
0.012,	0.0,	0.3537,	0.01024,	-0.00424,	0.354,	5.000e-04,	-1
0.01024,	-0.00424,	0.354,	0.006,	-0.006,	0.355,	5.000e-04,	-1
0.006,	-0.006,	0.355,	0.00176,	-0.00424,	0.356,	5.000e-04,	-1
0.00176,	-0.00424,	0.356,	0.0,	0.0,	0.357,	5.000e-04,	-1
0.0,	0.0,	0.357,	0.00176,	0.00424,	0.358,	5.000e-04,	-1
0.00176,	0.00424,	0.358,	0.006,	0.006,	0.359,	5.000e-04,	-1
0.006,	0.006,	0.359,	0.01024,	0.00424,	0.36,	5.000e-04,	-1
0.01024,	0.00424,	0.36,	0.012,	0.0,	0.361,	5.000e-04,	-1
0.012,	0.0,	0.361,	0.01024,	-0.00424,	0.362,	5.000e-04,	-1
0.01024,	-0.00424,	0.362,	0.006,	-0.006,	0.363,	5.000e-04,	-1
0.006,	-0.006,	0.363,	0.00176,	-0.00424,	0.364,	5.000e-04,	-1
0.00176,	-0.00424,	0.364,	0.0,	0.0,	0.365,	5.000e-04,	-1
0.0,	0.0,	0.365,	0.0,	0.0,	0.572,	5.000e-04,	-1
***Source***
1,	0
w5b,	0.0,	1.0
***Load***
0,	0
***Segmentation***
800,	80,	2.0,	2
***G/H/M/R/AzEl/X***
2,	5.0,	1,	50.0,	120,	60,	0.0

                      Mike

                      Comment

                      • #1541
                        Originally posted by YWYY View Post
                        Yes it seems very complicated, I normally use MMANA
                        I found a collinear on the web somewhere designed in MMANA - see below, just copy this text and paste into a text file.
                        Rename to ...ADSB.maa and open with MMANA

                        Code:
                        adsb-1090.maa
*
1090.0
***Wires***
31
0.0,	0.0,	0.0,	0.069,	0.0,	0.0,	5.000e-04,	-1
0.0,	0.0,	0.0,	0.0,	0.069,	0.0,	5.000e-04,	-1
0.0,	0.0,	0.0,	-0.069,	0.0,	0.0,	5.000e-04,	-1
0.0,	0.0,	0.0,	0.0,	-0.069,	0.0,	5.000e-04,	-1
0.0,	0.0,	0.0,	0.0,	0.0,	0.1376,	5.000e-04,	-1
0.0,	0.0,	0.1376,	0.00176,	-0.00424,	0.137,	5.000e-04,	-1
0.00176,	-0.00424,	0.137,	0.006,	-0.006,	0.138,	5.000e-04,	-1
0.006,	-0.006,	0.138,	0.01024,	-0.00424,	0.139,	5.000e-04,	-1
0.01024,	-0.00424,	0.139,	0.012,	0.0,	0.14,	5.000e-04,	-1
0.012,	0.0,	0.14,	0.01024,	0.00424,	0.141,	5.000e-04,	-1
0.01024,	0.00424,	0.141,	0.006,	0.006,	0.142,	5.000e-04,	-1
0.006,	0.006,	0.142,	0.00176,	0.00424,	0.143,	5.000e-04,	-1
0.00176,	0.00424,	0.143,	0.0,	0.0,	0.144,	5.000e-04,	-1
0.0,	0.0,	0.144,	0.00176,	-0.00424,	0.145,	5.000e-04,	-1
0.00176,	-0.00424,	0.145,	0.006,	-0.006,	0.146,	5.000e-04,	-1
0.006,	-0.006,	0.146,	0.01024,	-0.00424,	0.147,	5.000e-04,	-1
0.01024,	-0.00424,	0.147,	0.012,	0.0,	0.1473,	5.000e-04,	-1
0.012,	0.0,	0.1473,	0.012,	0.0,	0.3537,	5.000e-04,	-1
0.012,	0.0,	0.3537,	0.01024,	-0.00424,	0.354,	5.000e-04,	-1
0.01024,	-0.00424,	0.354,	0.006,	-0.006,	0.355,	5.000e-04,	-1
0.006,	-0.006,	0.355,	0.00176,	-0.00424,	0.356,	5.000e-04,	-1
0.00176,	-0.00424,	0.356,	0.0,	0.0,	0.357,	5.000e-04,	-1
0.0,	0.0,	0.357,	0.00176,	0.00424,	0.358,	5.000e-04,	-1
0.00176,	0.00424,	0.358,	0.006,	0.006,	0.359,	5.000e-04,	-1
0.006,	0.006,	0.359,	0.01024,	0.00424,	0.36,	5.000e-04,	-1
0.01024,	0.00424,	0.36,	0.012,	0.0,	0.361,	5.000e-04,	-1
0.012,	0.0,	0.361,	0.01024,	-0.00424,	0.362,	5.000e-04,	-1
0.01024,	-0.00424,	0.362,	0.006,	-0.006,	0.363,	5.000e-04,	-1
0.006,	-0.006,	0.363,	0.00176,	-0.00424,	0.364,	5.000e-04,	-1
0.00176,	-0.00424,	0.364,	0.0,	0.0,	0.365,	5.000e-04,	-1
0.0,	0.0,	0.365,	0.0,	0.0,	0.572,	5.000e-04,	-1
***Source***
1,	0
w5b,	0.0,	1.0
***Load***
0,	0
***Segmentation***
800,	80,	2.0,	2
***G/H/M/R/AzEl/X***
2,	5.0,	1,	50.0,	120,	60,	0.0

                        Mike

                        Here is the output in MMNA-GAL

                        YWYY-2-Geometry-MMANA.PNG . YWYY-2-View-MMANA.PNG . YWYY-2-Calculate-MMANA.PNG . YWYY-2-Far Field Plots-MMANA.PNG

                        Comment

                        • #1542
                          Originally posted by YWYY View Post
                          Hi I have downloaded 4nec2, will have a play. Any chance I can grab that model you did of my antenna. Email provided below.
                          Mike

                          newmail4@internode.on.net
                          Click the link below to download zip file "ywyy double whip".
                          ywyy double whip.zip

                          Unzip the downloaded file, you will get "ywyy double whip.nec".
                          Double click the unzipped fie and it will open in 4nec2 software***.

                          On NEC Main window, click on the Menu : Calculate -> NEC Output data - F7
                          (Or hit the button with green calculator icon)

                          Software will take about 30 seconds to run the simulation, then show simulation results (Geometry/Pattern/ SWR/ Impedance etc)

                          ***Those who don't have the modelling software 4nec2, can download it free of cost from http://www.qsl.net/4nec2/.
                          Last edited by abcd567; 2014-08-27, 00:23.

                          Comment

                          • #1543
                            I've made up the simple half wave dipole, with amplifier and put it outside - it's a temporary rig made up of bit's I had in the hobby room and shed. I will take it down within the next two weeks.

                            The amplifier is powered off a 12 Netgear Router PSU, the reciever is using the extra Baspberry Pi + Dongle I have for the feeder project

                            coax used for the dipole has a segmented polythene tube with 6 segments as air gaps.

                            View the results here http://goo.gl/1D0QaL - range is 150-175nm. Pictures...

                            One shows the dipole + amplifier with what is required for rain protection ... fixed to a gallows on a bamboo pole.

                            the other shows the bamboo pole loosely fixed to the main antenna mast - I'd have like to have got it higher but didn't have the coax length required

                            I'll post up a virtual radar plot once I've collected a couple of hours of data (done, the range rings are at 25nm)

                            IMG_1280.jpg IMG_1281.JPG Capture.PNG
                            Last edited by peterhr; 2014-08-26, 19:18.

                            Comment

                            • #1544
                              Originally posted by peterhr View Post
                              I've made up the simple half wave dipole, with amplifier and put it outside - it's a temporary rig..........

                              ..........coax used for the dipole has a segmented polythene tube with 6 segments as air gaps.......

                              ..........range is 150-175nm......

                              ......Pictures......
                              Thanks for the pictures and detailde information about the test setup & range. You have put in lot of work & effort and by posting these in forum, have benifited the forum members. Thanks again.

                              The 150-175 nm max range is not very encouraging, as other antennas give 250-275 nm max range.

                              I cannot visualize the physical costruction of segmented coax. Have never seen or heard of such a thing.

                              Comment

                              • #1545
                                People say having the antenna high makes little difference because these signals are line of sight, but it certainly helps enormously is and it removes the antenna from other noise sources and also from reflected clutter. It's doing 200nm in the best direction which I would think is getting the benefit of some refection from the neighbours roof.

                                It is important to get the antenna above the roofline to stop most of these effects, and over 250nm is difficult to achieve with a dongle over land at ground level. People with the antenna looking over water seem to get more and at height.

                                I have a reel of TV grade coax (supposed to be good to 700Mhz) - I'll put a length of that on (if it's dry and safe to get on the roof to do it) and shove the antenna up another 2m.



                                Thinking about the gain pattern on the coke can - that the lobes go down towards the can - might it work better inverted?
                                Last edited by peterhr; 2014-08-27, 09:26.

                                Comment

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