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Friday, September 28, 2007

Surfin': Looking for Log Periodics of the VHF/UHF Variety

This week, Stan searches for a tree guy and some new aluminum to replace the old. Read all about it in this week’s Surfin’. After you read Surfin’, you can leave your comments back here.

By the way, Surfin’ is a weekly column published on ARRLWeb that finds and features Web sites that are related to Amateur Radio, specifically, and radio, in general. If you have any suggestions for Surfin’, please contact WA1LOU using the e-mail link to the right.


  1. Stan,
    I have one of the Create 100-1200 MHz log periodics as well as a KMA 25-500 MHz LPDAs. I have only used the Create for receiving so I can't comment on swr for it. The KMA works great on 12, 10, and 6 meters but I have swr problems on 2 meters. A friend who has done extensive computer modeling thinks that log periodics need to scale element diameter with wavelength (so longer, low frequency elements are proportionally thicker) and that LPDAs do have a limit of 2:1 or perhaps 3:1 frequency ratio - the booms act as a feedline and you will get standing waves. Perhaps its not possible to make a LPDA with a 10:1 frequency ratio and have low swr across that spectrum. HF logs typically operate from 13-30MHz (or 10-30MHz) and so are within a 3:1 frequency ratio.

    Just my 2c.

    73 Warren K2ORS
    WD2XGJ (136-140 kHz)
    WD2XSH/23 (505-510 kHz)
    WE2XEB/2 (160-189 kHz)
    WE2XGR/1 (505-515 kHz)

  2. Hello Warren,

    Thank you for your 2 cents... I appreciate all the help I can get.

    BTW, I'm a big Gene Shepherd fan... love your call sign!


    Stan, WA1LOU