I got a few requests for the file. Here it is. This is the 3 element SteppIR
with an added reflector closer to the driven element. It would be easy to add
a director similarly. If you want to see the effect of such an element on the
other bands you would take the original dimentions for the other band and stick
this reflector in and see if it affects the pattern or swr. That's what
modeling is all about.
The file is easy to use because all variables are defined. You can change any
of the SY lines to suit your own needs.
It should not be necessary to change the GW lines.
The values in this file were determined by using the optimizer feature in 4NEC2
to get best f/b.
I used the latest release of 4NEC2 (5.8.7)
Rick K2XT
CM 3-element Yagi, ten meters, SteppIR elements, the 28.2 setting
CM 'The antenna will actually appear to be higher in freq. than in reality
due to loading of the elements by the fiberglass
CM 'This is the 28.2 configuration, but designed for 28.8 MHz
CM 'The fiberglass supports load the 28.8 lengths so they work at 28.2 MHz.
ok ?
CM 'Element dimensions are read out of the controller by using the create
menu
CM 'K2XT Sep 2011 - adding a new reflector fixed called REF2
CM 'Now have 25 db f/b, 12.5 db gain
CM 'Questions? email k2xt@arrl.net Sept 22, 2011
CM 'Other original SteppIR configurations available, email me.
CE
CE
SY DE=194 'Driven ele length originally 191.3
SY REF=195.5 'length of reflector in inches 195.5
SY REF2=203.7473 'length of new reflector in inches
SY DIR=178.8741 'Director length originally 182.3
SY RS=102 'reflector spacing in -x direction. This is original reflector
SY RS2=46.01819 'reflector spacing in -x direction. This is new reflector
SY DS=89.5 'director spacing. Fixed length.
SY ht=12*20 'yagi height 70 ft (i.e. 12 *70 ft since everything is in
inches)
GW 1 41 -RS -REF/2 ht -RS REF/2 ht .25 'Original
Reflector
GW 4 41 -RS2 -REF2/2 ht -RS2 REF2/2 ht .25 'New
fixed reflector added
GW 2 41 0 -DE/2 ht 0 DE/2 ht .25 'driven ele. -
note it is longer than original, from optimizer
GW 3 41 DS -DIR/2 ht DS DIR/2 ht .25 'Note the
director is shorter than original
GS 0 0 .0254 'Scaling so u can input inches, like the SteppIR
controller displays
GE 1
GN 2 0 0 0 13 .005
EX 0 2 21 0 13 0.005
FR 0 1 0 0 28.8 1 'The design freq. is 28.8 but the
antenna works at 28.2
EN
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