NEC-LIST: Is a Compact Loop a Loop or a Small Folded Dipole ?

John,
 
I read your comments about the Compact Loop with interest. My
calculations resulted in the same radiation resistance and efficiency.
 
I have two suggestions that would increase the radiation resistance
and hence efficiency.
 
1. If the loop is divided into four quadrants and each quadrant is fed
separately, the radiation resistance and efficiency will increase
significantly !
 
2. Another way to increase radiation resistance and efficiency would
be to increase the inductance of the loop by imbedding the loop into a
ferrite core. For this one could decrease the loop size, e.g., to a 30
by 30 cm square loop, and use a ferrite (Ni Zn )with mu = 100, and
reduce the conductor dia. to say 1 cm. All this is equivalent to
increasing the effective height of the loop ! My calculations with
this example show 67 milliohm rad. res. and 61 % efficiency.
 
Example 2. would be much more effective, than example one. Of course,
one has to make certain that the ferrite does not saturate, if the
loop is used as a transmitting antenna.
 
Max J. Schmitt
Received on Thu Jun 25 1998 - 10:05:46 EDT