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Re: Info needed for MBM88 Antena



"George Liepins" <gliepins@nc.rr.com> wrote:
>Some years ago I bought two MBM88 70cm yagies made by Jaybeam Limited in UK.
>I was going to phase them, but never got to it.  Instead I kept the HyGain
>70 cm for satellite work.
>
>I have a friend who is interested in my antena, and wonders if it is
>"circularly polarized."  As far as I can tell, it can be set up for vertical
>or horizontal polarization, but circular?  The technical specs don't mention
>polarization specifics, except mentioning beamwidth E and H plane ( 28 and
>23 deg's respectively).
>
>Can someone , please, enlighten me concerning this antena, and how it could
>work as uplink for AO-40.

You are right, the Jaybeam "Multibeam" MBM yagis are linearly polarized.  The design is effectively a double-yagi with a slot-feed driven element.  Since you have two of them, of course you could put one in each plane and phase them for circular polarisation like any other pair of linear polarized antennas.

Be careful about the matching of the phasing harness, though.  My recollection is that these yagis are 75 ohm impedance.

Neill
G4HLX

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