They give the designer additional degrees of freedom with which to
control input impedance and side lobe structure. Side lobes can be
addressed with level/phase of radiation from the "sides" (bent back)
portions of the DE and impedance can be impacted by the length to
depth ratio of the "loop" or the coupling between the DE and REF.
These freedoms in turn allow the first director to be used more for
pattern/gain than impedance matching as typically occurs with a
traditional Yagi/OWA design.
Of course this freedom comes at the expense of increased mechanical
complexity - particularly in the OP-DES ("C shaped driven element")
designs.
73,
... Joe, W4TV
On 3/19/2013 1:42 PM, john@kk9a.com wrote:
What is the advantage of using full loop and C shaped driven elements?
John KK9A
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