Miracle Antenna Mixed Mode Dipole

Discussion in 'Amateur Radio Equipment Reviews' started by AD4ZU, May 27, 2010.

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  1. K8JD

    K8JD Ham Member QRZ Page

    The more reviews of manufactured "Miracle" and "wonder" antennas I read , the more I see that hams who have the biggest praise of these are also the hams with the least experience with different antennas and the least understanding of antenna theory !
    "Wow the Super DX 9999 antenna is the best one I ever had !, and the first too.."
     
  2. AA5CB

    AA5CB Ham Member QRZ Page

    MMD- a good, proven idea

    I've been using RFD (resonant feed-line dipoles) for decades; for 2-meter and lower other bands. They are super simple to build, simple to put up, and they work great on the band they are designed for. You can use a tuner to force them to other bands BUT expect the common-mode currents cause problems- just like a common dipole tuned to other bands.

    You can get this 'store-bought' one or build one yourself from this link or a host of other articles on RFD's:
    http://www.worldradiomagazine.com/wro_issues/2010/WRO_1010_14-29.pdf

    We use cheap RG-6 or RG-59 coax (single and double-shielded) from Lowe's at $24/100-ft with a twenty turns on a 6" form (PVC or whatever) or 10 turns on F240-61 toroids with consistant good results working the world.
     
  3. G3TXQ

    G3TXQ Ham Member QRZ Page

    Not just CM problems, you can also expect lots of loss.

    In many of these designs - including the commercial one and the World Radio Magazine one - the feedline is RG174. So, if you try to force a 40m version into use on 20m you can expect a loss of 10dB just within the 33ft of feedline making up one half of the antenna; 20dB loss if you add another 34 ft to reach the radio.

    But it's a nice solution for single-band use.

    Steve G3TXQ
     
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