SL FM Yagi @ 91.5 - opt
Free Space Symmetric
91.500 MHz
10 6061-T6 wires, inches
rfs = -23		; space = 24.75" - 23.0"   
des = 0.00		; no change  
drs1 = 12		; space = 19.063" - 12.00" 
drs2 = 42		; space = 39.5" - 42.0"   	
dia = .392		; 25/64" = 0.392" for Refl + Drv El
dia1 = .375		; 3/8" = 0.375" for Dr1, Dr2
rfl = 31.75		; length = 31.875" - 31.75"
dr1 = 28		; length = 23.188" - 28.00" 
dr2 = 28.5		; length = 23.188" - 28.50" 

len = 27.75		; dr el half-length; org length = 27.75"
sp = 1.824		; dr el upside dipole spacing	
nsp = -1.46		; dr el downside dipole spacing

 1   0     -len   nsp   0      len   nsp    dia
 1   0     -len   sp    0      len    sp    dia
 1   0     -len   sp    0     -len   nsp    dia
 1   0      len   sp    0      len   nsp    dia

 1   rfs    -rfl   0    rfs     0.0    0    dia
 1   rfs     0.0   0    rfs     rfl    0    dia 
 1   drs1   -dr1   0    drs1    0.0    0    dia1
 1   drs1    0.0   0    drs1    dr1    0    dia1 
 1   drs2   -dr2   0    drs2    0.0    0    dia1
 1   drs2    0.0   0    drs2    dr2    0    dia1 
 1 source
 Wire 1, center

 This antenna was modeled from visual measurements of the Stellar Labs 4el FM 
 Antenna as delivered and optimized for 104.9Mhz. AO analysis;
   9.3 db F/G 
   9.5 db F/B
  300 ohm feed impedance - 301 + j 7 
  SWR = 1.03:1

 To receive the FM station from Los Angeles @ 91.5 Mhz - KUSC, both directors
 were lengthened, reflector decreased for F/G and good SWR at the low end of 
 the FM band.

 The antenna has a 300 to 75 stripline transformer built into the feed point
 making the transmission line (RG-6) a better way to send the signal to my
 FM tuner. Add three (3) ferrite line chokes (apx 1000 ohms) at the feed point
 to further attenuate the common mode signal.