Simulation Fun: Rotary 5-Band Antennas - Let's Compare Them

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by SP3L, Jan 25, 2016.

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  1. RA3WDK

    RA3WDK Ham Member QRZ Page

    Jacek, Hello !

    Please check Email for 16 Jan. i sent zip file. I sent Email again today morning.

    73!
    Ivan
     
  2. SP3L

    SP3L Ham Member QRZ Page

    Got it this morning!
    I will present the results in a several days. I am finalizing Nick's latest yagi right now.

    73
    Jacek
     
  3. SP3L

    SP3L Ham Member QRZ Page

    And here it is. Another high gain multi-element Yagi by UA3TW. The antenna looks as complex as the previous Nick’s design of May 2016.
    upload_2017-1-20_15-9-45.png
    It seems that this time Nick had focused on minimizing SWR. Look at the SWR plots of the previous model and the present one.
    upload_2017-1-20_15-10-11.png
    upload_2017-1-20_15-10-25.png

    upload_2017-1-20_15-10-34.png
    upload_2017-1-20_15-10-47.png

    Boths Yagis work up to about 28.7 MHz. SWR of the new model looks better that the older one.

    I had calculated the overall system gain (antenna gain - losses in the transmission line) and found out that it improved for the 15 m band but, unfortunately, got worse a bit for the other bands. Compare the plots in green and dark blue colors.
    upload_2017-1-20_15-12-25.png

    The F/B when compared with the May 2016 design, improved only for the 10 m band.
    upload_2017-1-20_15-13-21.png

    Of course, this is still a very high gain HF Yagi and I am comparing it with only the best antennas covered in this thread. But if the results of the MMANA-GAL modeling matched those of the the 4nec2 simulator, I would rather choose the previous Nick’s design as my favorite. Both antennas look for me equally complex to build but the old design offered somewhat better gain and F/B performance when all bands are considered. Anyway, thank you very much Nick for sharing your model.

    As always, the updated Comparison Table and the Model Pack are attached.

    73
    Jacek
     

    Attached Files:

    UA3TW likes this.
  4. UA3TW

    UA3TW Ham Member QRZ Page

    Thank you very much Jacek.
    In fact the antenna has significant difference in approach from the previous one, and consequently it has fewer wire elements. Never mind - they look alike at first sight.
    I'd like to put two more EZNEC models. First one has better RP and GAIN on 17m, second one does not have wire elements - they are substituted by hanging tube elements in a manner of 'hidden open sleeve' elements by OPTIBEAM.
    By the way I checked a few antennas in EZNEC if they are coated with 2mm of ise and came to conclusion that all narrowband antennas are lousy because they are completely carried way over frequency. For example my this antenna goes down to 27-27.5 MHz on 10m, to 24.25 MHz on 12m, to 20.75 MHz on 15m, to 17.5 MHz on 17m, to 13.95 MHz on 20m. The RPs are completely destroyed on 12 and 17m bands.
    I began to realise the goods of LPDA and the like, including your Cat Whiskers approach.
     

    Attached Files:

  5. SP3L

    SP3L Ham Member QRZ Page

    Nick,
    I was going to wait a couple of months with presenting this little discovery until I do some real world experiments. But as you are now aiming in the bandwidth improvement, I think I will create a new thread to describe what I have found.
    I will call it: "Probably the simplest trick to improve antenna bandwidth".
    73
    Jacek
     
  6. SP3L

    SP3L Ham Member QRZ Page

    RA3WDK 5-Band Yagi/Moxon with Open Sleeve Coupling

    I do not know if Ivan would call his antenna exactly in this way, but to me it looks like a combination of Yagi and Moxon. There is only one driven element (20-m band radiator) connected directly to the source. The other radiators are getting energy via capacitive coupling often called open sleeve coupling. See the picture below. It seems to me that there are two elements in 20-meter through 12-meter bands and three elements in 10-meter band in Ivan’s design.
    upload_2017-1-27_8-39-48.png
    The boom is relatively short: 3.95 m and the antenna length (or width) is smaller than 20-meter band Yagi and equals 8.38 m. Turn radius is about 4.7 m what is less than the Spiderbeam (5 m).

    The antenna has been modeled in the MMANA-GAL program and I decided not to convert it to 4nec2 format because stepped diameter elements are used in the model. It is known that the MiniNEC engine used in the M-G manages such designs better than the NEC2 engine in the 4nec2 or EZNEC.

    Considering the bandwidth, the antenna covers completely 3 bands with low SWR but has a little problem in the higher end of the 15-m band where SWR peaks to 5.37. 10-m band is covered up to ca. 28.85 MHz what is quite OK for the Yagi type antenna.. The SWR plots of those two not fully covered bands are shown below.

    upload_2017-1-27_8-42-4.png
    upload_2017-1-27_8-42-16.png
    Now, the most interesting part. The graph below shows the signal gain when the antenna is connected via 30 m long RG58 coax compared with some other antennas covered in this thread and referred to a half wave dipole.
    upload_2017-1-27_8-44-3.png
    As you can see, the antenna has quite decent gain, comparable with 2-element monoband Yagis on almost all bands except the 15-meter band. Due to high SWR at 21.45 MHz, extra 1.8 dB is lost in the transmission line even if you use an ATU at the transceiver end of the coax. Moreover, the antenna has somewhat smaller gain itself on this band when compared to the other bands. Due to that, at 21.45 MHz, it is only slightly better than a dipole.

    Having said that, the antenna still beats the Hexbeam and 5-band Moxon in system gain for most frequencies. It is also better than the Spiderbeam in 6 out of 10 test frequencies . All in all, that is very acceptable design. If Ivan could improve a bit the 15-m band it would be almost perfect.

    In terms of F/B, the RA3WDK is so-so.
    upload_2017-1-27_8-47-41.png

    However, this parameter can be sometimes misleading. I suggest you study the radiation patterns simulated over real ground (not free space). And here they are.
    upload_2017-1-27_8-48-7.png

    upload_2017-1-27_8-48-20.png

    upload_2017-1-27_8-48-38.png

    upload_2017-1-27_8-49-2.png

    upload_2017-1-27_8-49-18.png
     
  7. SP3L

    SP3L Ham Member QRZ Page

    The updated models and comparison table - attached.

    73
    Jacek
     

    Attached Files:

  8. RA3WDK

    RA3WDK Ham Member QRZ Page

    Jacek, thank you very much for your investigation !
    Good result !
    I made model for real HAM activity on HAM bands. Also i work 99% QSO CW and look for better SWR in CW part of bands.
    Most often DX peditions has band plan below 21300 for SSB part.
    It`s was very hard got some good performance for "open sleeve" on 5 bands, and this antenna is very low cost, very light (for G-450 and G-600 rotor).
    Also this antenna does not afraid bad WX (ice and snow) , SWR does not increase to dangerous level.

    Jacek, again thank you for your interesting comparison !

    73!
    Ivan
     
  9. UA3TW

    UA3TW Ham Member QRZ Page

    This is a MMANA model of shorter boom of 6.65m:
    Pentabander Yagi 20-17-15-12-10 Boom 6.65m long
    *
    28.4
    ***Wires***
    44
    0.0, -5.27, 0.0, 0.0, 5.27, 0.0, 0.01, -1
    5.66955, -4.66, 0.0, 5.66955, 4.66, 0.0, 0.01, -1
    2.83478, 0.02, 0.0, 2.83478, 5.15, 0.0, 0.01, -1
    2.83478, -0.02, 0.0, 2.83478, -5.15, 0.0, 0.01, -1
    2.83478, 0.02, 0.0, 2.83478, -0.02, 0.0, 0.002, -1
    2.83478, 0.02, 0.0, 3.21785, 0.02, 0.0, 0.01, 20
    2.83478, -0.02, 0.0, 3.21785, -0.02, 0.0, 0.01, 20
    3.21785, 0.02, 0.0, 3.21785, 3.44, 0.0, 0.008, -1
    3.21785, -0.02, 0.0, 3.21785, -3.44, 0.0, 0.008, -1
    1.45569, -3.52, 0.0, 1.45569, 3.52, 0.0, 0.008, -1
    4.4437, -3.31, 0.0, 4.4437, 3.31, 0.0, 0.008, -1
    6.28248, -3.27, 0.0, 6.28248, 3.27, 0.0, 0.008, -1
    2.83478, -0.02, 0.0, 2.4517, -0.02, 0.0, 0.01, 20
    2.83478, 0.02, 0.0, 2.4517, 0.02, 0.0, 0.01, 20
    2.4517, 0.02, 0.0, 2.4517, 2.594, 0.0, 0.006, -1
    2.4517, -0.02, 0.0, 2.4517, -2.594, 0.0, 0.006, -1
    3.56263, -2.518, 0.0, 3.56263, 2.518, 0.0, 0.006, -1
    4.71186, -2.492, 0.0, 4.71186, 2.492, 0.0, 0.006, -1
    5.36309, -2.488, 0.0, 5.36309, 2.488, 0.0, 0.006, -1
    6.62725, -2.432, 0.0, 6.62725, 2.432, 0.0, 0.006, -1
    1.12625, 2.974, 0.0, 1.12625, -2.974, 0.0, 0.006, -1
    6.28248, 2.8, -0.1, 6.28248, 0.0, -0.35, 0.001, -1
    6.28248, -2.8, -0.1, 6.28248, 0.0, -0.35, 0.001, -1
    4.4437, 2.84, -0.1, 4.4437, 0.0, -0.35, 0.001, -1
    4.4437, -2.84, -0.1, 4.4437, 0.0, -0.35, 0.001, -1
    6.28248, 2.426, 0.1, 6.28248, 0.0, 0.35, 0.001, -1
    6.28248, -2.426, 0.1, 6.28248, 0.0, 0.35, 0.001, -1
    4.4437, 2.452, 0.1, 4.4437, 0.0, 0.35, 0.001, -1
    4.4437, -2.452, 0.1, 4.4437, 0.0, 0.35, 0.001, -1
    0.0, -3.85, 0.1, 0.0, 0.0, 0.4, 0.001, -1
    0.0, 3.85, 0.1, 0.0, 0.0, 0.4, 0.001, -1
    2.83478, 0.02, 0.0, 2.83478, 0.01, 0.01, 0.002, -1
    2.83478, -0.02, 0.0, 2.83478, -0.01, 0.01, 0.002, -1
    2.83478, 0.01, 0.01, 2.83478, -0.01, 0.01, 0.002, -1
    5.66955, -4.13, 0.1, 5.66955, 0.0, 0.4, 0.001, -1
    5.66955, 4.13, 0.1, 5.66955, 0.0, 0.4, 0.001, -1
    2.83478, -0.02, 0.0, 2.83478, -0.2, -0.35, 0.001, -1
    2.83478, 0.02, 0.0, 2.83478, 0.2, -0.35, 0.001, -1
    2.83478, -0.02, 0.0, 2.83478, -0.3, 0.6, 0.001, -1
    2.83478, 0.02, 0.0, 2.83478, 0.3, 0.6, 0.001, -1
    2.83478, 3.763, 0.1, 2.83478, 0.3, 0.6, 0.001, -1
    2.83478, -3.763, 0.1, 2.83478, -0.3, 0.6, 0.001, -1
    2.83478, 2.78823, -0.09947, 2.83478, 0.2, -0.35, 0.001, -1
    2.83478, -2.78823, -0.09947, 2.83478, -0.2, -0.35, 0.001, -1
    ***Source***
    1, 0
    w5c, 0.0, 1.0
    ***Load***
    1, 1
    w34c, 0, 0.0, 47.0, 0.0
    ***Segmentation***
    400, 40, 2.0, 2
    ***G/H/M/R/AzEl/X***
    0, 22.0, 4, 50.0, 120, 60, 0.0
     
  10. SP3L

    SP3L Ham Member QRZ Page

    Hello, Nick,

    thanks for your contribution. I will simulate your new design in a few days and post the results here.
    73
    Jacek
     
    UA3TW likes this.

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