Cleveland RAYNET Group

Directional aerials

These are usually either beam aerials or loop aerials.  The polar diagram of the aerial may be directional as it receives a strong signal in one direction (front lobe) or because it receives a minimum signal in one direction (cardioid or heart shaped).

Even a simple one piece half wave dipole aerial can be used.  This has a polar diagram signal strength response shaped like a figure eight.  You use it to find the bearing with minimum signal strength.  You can't tell if the target is "this" way along the bearing or "that" way along the same line, from a single location.  Bearings taken at more than one location will produce lines which cross, so the location of the target will be known.

Loop aerials could be a single loop of small diameter flexible metal tube, or more complicated.  Like all aerials, it mainly depends on the frequency used.  The loop may be a circle, square, octagon or a variety of shapes.

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Updated on 21 June 2006