How to evaluate an antenna's performance

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by K7HUT, Feb 26, 2021.

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  1. K7HUT

    K7HUT Ham Member QRZ Page

    "A very good way to compare the performance of various antennas is to monitor your signal on a remote SDR receiver...........there are many of those all over the world

    Frank , EI7KS"


    That sounds like a pretty cool idea, any links to how to do this... I'll google around as well.
     
  2. KE8QEP

    KE8QEP XML Subscriber QRZ Page

    First off, how to you propose one learns?
    Second, the OP made some tests which is more than most people do, and it was a comparison as the OP recognized. The OP also realized there were other things to consider, which it what he was asking about.
     
    KI4ZUQ and PU2OZT like this.
  3. KM3F

    KM3F Ham Member QRZ Page

    Bringing to attention Is the first lesson.
     
  4. W9WQA

    W9WQA Ham Member QRZ Page

    and how to set up, a practical test

    get a 2nd ham to join you
     
    K7HUT likes this.
  5. WB5YUZ

    WB5YUZ Ham Member QRZ Page

    I prefer to keep a reference antenna on hand, a dipole or a vertical. New antennas are compared to it using an A/B switch. If the performance of the two antennas is close, this may not be useful; but it will often find a defect in new antenna construction very quickly!
     
  6. W2AAT

    W2AAT XML Subscriber QRZ Page

    KJ7PXJ, congrats on being a new Tech. Your doing research, experimenting and searching out answers and recommendations is the right thing for you to be doing. Unfortunately, in our hobby there are so many hams who memorize the answers to the questions but never ask the question "why are they asking this question?". Unfortunately posts like yours open the doors for those who give responses like in this post. Don't be discouraged..... If you continue doing what you are doing, you will learn, intellectually grow and surely enjoy the many aspects of our hobby... But...keep this post in the back of your mind because as you gain knowledge you surely don't want to share your knowledge in a manner similar to this post....

    I look forward to the time when we meet and chat on the air... Corky
     
    PU2OZT, K7HUT and KE8QEP like this.
  7. KM3F

    KM3F Ham Member QRZ Page

    W2AAT, I'm sorry you feel that way.
    I did go on to explain and offer a perspective but you failed to take that into account.
    I had no knowledge of his back ground and can only answer to the post as he presented it.
    He could have been a Phd and not know it.
     
  8. KD5PME

    KD5PME Ham Member QRZ Page

    You had no knowledge of his background because you didn't ask. Instead of asking questions to the OP, you made an erroneous assumption and then went on to vent. Shame on you.
     
    KI4ZUQ likes this.
  9. AI3V

    AI3V Ham Member QRZ Page

    Are the 2 antennas similar?

    For example, 2 basic quarter wavelength whips should obviously be identical.

    Or are they something like 2 physically different "dual band" antennas from different manufacturers?

    One could have a manufacturing defect, or some type of similar problem, like a busted matching network.

    Or, it could be like a 2m/70cm dual band I had years ago, that was made in such a way that the VSWR was fine on both bands, but because of the way it was built it sent the 70cm signal closer to straight up than out to the horizon.

    In any case, I commend you for doing a actual a-b comparison, few hams could be bothered, and as a result have a wimpy signal because of a lousy antenna.

    Rege
     
    K0UO and K7HUT like this.
  10. K7HUT

    K7HUT Ham Member QRZ Page

    @AI3V the two antenna are not too similar. Larsen 2/70sh vs a Comet 2x4sr-nmo. Both are dual band, but construction is definitely different, and they are of different wavelength design on both bands.
    The latter is far outperforming the second at UHF.

    Now that you mention it, the Larsen has been knocked around a bit, going back and forth under the garage door.
    I wonder if some mechanical damage occurred over many cycles of bending and snapping back.

    I am getting a couple more dual band options to test.
    I am going to go through 2m and 70cm and GMRS wavelengths, to compare received field strength on all the various antenna.
    Again the only variable will be the antenna, as the transmitter, cabling, NMO mount, etc, will be identical for all antenna under test.

    Re radiation patterns, I have to assume that the radiation patterns are horizontal and non directional, and if they aren't the antenna might as well be broken or useless for my application.
     
    AI3V likes this.

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