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Re: [loopantennas] Rotating the null direction without moving the antenna

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  • Jay Heyl
    ... As the other replies have made clear, it is certainly possible. My reading on the topic has suggested that better null steering is achieved with the
    Message 1 of 8 , Jan 6 7:11 PM
      On Tue, Jan 6, 2009 at 1:13 PM, Misha <3ym3ym@...> wrote:

      > But I still would like to be able to control the null direction
      > remotely. My feeling is that if signals from 2 orthogonal loops are
      > added with a variable phase shift, the null direction may rotate with
      > the phase change.


      As the other replies have made clear, it is certainly possible. My reading
      on the topic has suggested that better null steering is achieved with the
      antennas as far apart as possible and slightly off from orthogonal, say 75
      degrees instead of 90. This may vary depending on the specifics of the loops
      and the frequencies in question. The limited experience I have is with
      phasing antennas for MW reception so it may not be the same with SW
      reception.

      -- Jay


      [Non-text portions of this message have been removed]
    • tsmithers@cix.co.uk
      ... As well as the MFJ/Timewave units already mentioned the NCC-1 phaser from DX Engineering may be of interest
      Message 2 of 8 , Jan 7 2:09 AM
        >My feeling is that if signals from 2 orthogonal loops are
        >added with a variable phase shift, the null direction may rotate with
        >the phase change.

        As well as the MFJ/Timewave units already mentioned the NCC-1 phaser from DX Engineering
        may be of interest
        http://www.dxengineering.com/Parts.asp?ID=1227&PLID=215&SecID=114&DeptID=12&PartNo=
        DXE%2DNCC%2D1

        73 to all
        Trevor G0KTN
      • Jim Dunstan
        ... Hi, This is how the crossed loops in shipboard LF directional antennas work .... the loops are mounted perpendicular to each other ... the feed lines
        Message 3 of 8 , Jan 7 6:56 AM
          At 03:13 PM 1/6/2009 +0000, you wrote:

          >I plan to install a loop antenna on my backyard, receive only. The
          >plan is to not tune it and to use a broadband preamp, for matching the
          >impedance and for insulating the antenna from the common mode noise
          >pickup on the feeder.
          >But I still would like to be able to control the null direction
          >remotely. My feeling is that if signals from 2 orthogonal loops are
          >added with a variable phase shift, the null direction may rotate with
          >the phase change.
          >Did anybody experiment with a setup like this?

          Hi,

          This is how the crossed loops in shipboard LF directional antennas work
          .... the loops are mounted perpendicular to each other ... the feed lines
          (parallel) are brought down to the radio room and connected to a
          'goniometer' .... crossed inductors .... with a rotating pickup loop
          inside. The effect is as if a single loop was being rotated.

          Jim


          >

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