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1:1 BALUN for UHF

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by LZ1MAK, Sep 25, 2018.

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  1. LZ1MAK

    LZ1MAK Ham Member QRZ Page

    Hello,

    I just finished a small double loop antenna for 430MHz. Easy to tune and build. SWR<1.2

    I want to add 1:1 BALUN to stable the parameters and found a BALUN design with coax. What do you think, is this BALUN effective for UHF and for the 1/4 section what coax do I need 50/75 Ohm? I am talking for the BALUN from the left side. Thank you
    Thank you double loop.jpg 1-1 BALUN.JPG double loop.jpg 1-1 BALUN.JPG
     
  2. SM0GLD

    SM0GLD Ham Member QRZ Page

    All you need is one or two ferrite sleeves.

    /Mike
     
  3. W2WDX

    W2WDX Subscriber QRZ Page

    Transmission line baluns are more for converting balanced to unbalanced feedpoints and transforming impedance, if needed.

    If your concern is for reducing CMC on the feedline then the info below relates more:

    Well that's a big generalization!

    In order for ferrites to be effective on UHF or VHF the proper mixture must be used. Type 61 is quite good at UHF, and you must calculate the correct number of sleeves for the amount of choking impedance you want to achieve. Like anything, good engineering always trumps anecdotal generalizations.

    Here's a good paper on the subject: https://www.fair-rite.com/wp-content/uploads/2015/08/CUP-Paper.pdf

    At the end of the paper they discuss common-mode, which is the relevant data for what you're doing.
     
    Last edited: Sep 25, 2018
    NH7RO likes this.
  4. LZ1MAK

    LZ1MAK Ham Member QRZ Page

    Thank you very much!!! Have a nice day and many DX
    Marin
     

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