The Antenna Performance Specialties APS-13 is a log-Yagi array with 13 elements on a 197″ boom. Five of the elements are driven. A shorted phasing line terminates at a passive reflector.
I modeled the antenna with the AO 9.67 Antenna Optimizer. This image shows the antenna geometry.
This shows phasing line and feedpoint detail. I added a wire across the feedpoint terminals and placed a source at its center. Blue dots mark analysis segments. The red dot is the feedpoint.
Calculated performance is for 60 analysis segments per conductor halfwave. Forward gain includes mismatch and conductor losses and correction by pattern integration. F/R is the ratio of forward power to that of the worst backlobe in the rear half-plane.
Frequency Impedance SWR Mismatch Conductor Forward F/R
MHz ohms Loss dB Loss dB Gain dBd dB
88 204+j136 1.93 0.46 0.12 8.55 20.27
89 170+j85 1.97 0.49 0.08 8.62 23.74
90 161+j99 2.13 0.61 0.07 8.55 25.57
91 174+j114 2.07 0.56 0.06 8.64 26.78
92 195+j120 1.91 0.45 0.05 8.82 28.05
93 217+j117 1.74 0.33 0.05 9.00 29.60
94 234+j107 1.60 0.24 0.04 9.17 30.79
95 246+j96 1.50 0.17 0.04 9.32 31.90
96 252+j85 1.42 0.13 0.04 9.47 33.02
97 257+j74 1.36 0.10 0.03 9.61 34.37
98 259+j64 1.32 0.08 0.03 9.76 35.70
99 257+j54 1.28 0.07 0.03 9.91 36.81
100 249+j44 1.28 0.07 0.03 10.04 33.45
101 235+j40 1.33 0.09 0.03 10.14 31.57
102 217+j47 1.45 0.15 0.04 10.20 30.42
103 203+j65 1.60 0.24 0.04 10.20 29.77
104 199+j93 1.74 0.33 0.04 10.15 29.50
105 212+j119 1.78 0.36 0.05 10.09 29.41
106 232+j121 1.68 0.29 0.06 10.02 29.32
107 204+j101 1.74 0.33 0.07 9.64 29.74
108 127+j156 3.10 1.32 0.12 8.05 31.10
APS-13 Free Space 98.000 MHz 89 6063-T832 wires, inches rp = 0 ; element positions e1p = 9.25 e2p = 20.875 e3p = 32.5 e4p = 44.125 e5p = 55.75 d1p = 51.75 d2p = 69.375 d3p = 90 d4p = 113 d5p = 138.75 d6p = 165.75 d7p = 196.75 eqd = 1.28 ; element + mounting plate equivalent diameter d = .11 ; phasing-line diameter r = 1.875 / 2 ; spacing of rivets on insulated elements b = .75 ; feedpoint bolt length x1 = 3 ; x at first phasing-line bend e = e1p - rp ; phasing line length (R-DE1) s2 = .5 / 2 ; phasing-line half-spacing at crossover point x2 = 3.125 ; x at second bend x3 = e - x2 ; x at third bend x4 = e - x1 ; x at fourth bend e2 = e / 2 ; half of element spacing y1 = r * (1 - x1 / e2) ; y at first bend y2 = r * (1 - x2 / e2) ; y at second bend f = e2p - e1p ; phasing line length (DE1-DE2 ... DE4-DE5) s1 = .375 / 2 ; phasing-line half-spacing at crossover point w2 = 3.4375 ; x at second bend x5 = f - w2 ; x at third bend x6 = f - x1 ; x at fourth bend f2 = f / 2 ; half of element spacing y5 = r * (1 - x1 / f2) ; y at first bend y6 = r * (1 - w2 / f2) ; y at second bend 1 rp -33.25 0 rp -2 0 0.375 1 rp -2 0 rp -1.25 0 eqd 3 rp -1.25 0 rp 1.25 0 eqd 1 rp 1.25 0 rp 2 0 eqd 1 rp 2 0 rp 33.25 0 0.375 1 e1p -29.75 0 e1p -r 0 0.375 1 e1p r 0 e1p 29.75 0 0.375 1 e2p -28.625 0 e2p -r 0 0.375 1 e2p r 0 e2p 28.625 0 0.375 1 e3p -26.25 0 e3p -r 0 0.375 1 e3p r 0 e3p 26.25 0 0.375 1 e4p -25.125 0 e4p -r 0 0.375 1 e4p r 0 e4p 25.125 0 0.375 1 d1p -26.125 -2 d1p -2 -2 0.375 1 d1p -2 -2 d1p 2 -2 eqd 1 d1p 2 -2 d1p 26.125 -2 0.375 1 e5p -17 0 e5p -r 0 0.375 1 e5p -r 0 e5p -r -b 0.125 zinc 4 e5p -r -b e5p r -b #16 copper 1 e5p r 0 e5p r -b 0.125 zinc 1 e5p r 0 e5p 17 0 0.375 1 d2p -25.625 0 d2p -2 0 0.375 1 d2p -2 0 d2p 2 0 eqd 1 d2p 2 0 d2p 25.625 0 0.375 1 d3p -25.125 0 d3p -2 0 0.375 1 d3p -2 0 d3p 2 0 eqd 1 d3p 2 0 d3p 25.125 0 0.375 1 d4p -25 0 d4p -2 0 0.375 1 d4p -2 0 d4p 2 0 eqd 1 d4p 2 0 d4p 25 0 0.375 1 d5p -24.625 0 d5p -2 0 0.375 1 d5p -2 0 d5p 2 0 eqd 1 d5p 2 0 d5p 24.625 0 0.375 1 d6p -24 0 d6p -2 0 0.375 1 d6p -2 0 d6p 2 0 eqd 1 d6p 2 0 d6p 24 0 0.375 1 d7p -22.5 0 d7p -2 0 0.375 1 d7p -2 0 d7p 2 0 eqd 1 d7p 2 0 d7p 22.5 0 0.375 2 0 1.25 0 x1 y1 0 d 1 x1 y1 0 x2 y2 -s2 d 6 x2 y2 -s2 x3 -y2 -s2 d 1 x3 -y2 -s2 x4 -y1 0 d 2 x4 -y1 0 e -r 0 d 2 0 -1.25 0 x1 -y1 0 d 1 x1 -y1 0 x2 -y2 s2 d 6 x2 -y2 s2 x3 y2 s2 d 1 x3 y2 s2 x4 y1 0 d 2 x4 y1 0 e r 0 d shift x e1p 3 0 r 0 x1 y5 0 d 1 x1 y5 0 w2 y6 -s1 d 8 w2 y6 -s1 x5 -y6 -s1 d 1 x5 -y6 -s1 x6 -y5 0 d 3 x6 -y5 0 f -r 0 d 3 0 -r 0 x1 -y5 0 d 1 x1 -y5 0 w2 -y6 s1 d 8 w2 -y6 s1 x5 y6 s1 d 1 x5 y6 s1 x6 y5 0 d 3 x6 y5 0 f r 0 d shift x e2p 3 0 r 0 x1 y5 0 d 1 x1 y5 0 w2 y6 -s1 d 8 w2 y6 -s1 x5 -y6 -s1 d 1 x5 -y6 -s1 x6 -y5 0 d 3 x6 -y5 0 f -r 0 d 3 0 -r 0 x1 -y5 0 d 1 x1 -y5 0 w2 -y6 s1 d 8 w2 -y6 s1 x5 y6 s1 d 1 x5 y6 s1 x6 y5 0 d 3 x6 y5 0 f r 0 d shift x e3p 3 0 r 0 x1 y5 0 d 1 x1 y5 0 w2 y6 -s1 d 8 w2 y6 -s1 x5 -y6 -s1 d 1 x5 -y6 -s1 x6 -y5 0 d 3 x6 -y5 0 f -r 0 d 3 0 -r 0 x1 -y5 0 d 1 x1 -y5 0 w2 -y6 s1 d 8 w2 -y6 s1 x5 y6 s1 d 1 x5 y6 s1 x6 y5 0 d 3 x6 y5 0 f r 0 d shift x e4p 3 0 r 0 x1 y5 0 d 1 x1 y5 0 w2 y6 -s1 d 8 w2 y6 -s1 x5 -y6 -s1 d 1 x5 -y6 -s1 x6 -y5 0 d 3 x6 -y5 0 f -r 0 d 3 0 -r 0 x1 -y5 0 d 1 x1 -y5 0 w2 -y6 s1 d 8 w2 -y6 s1 x5 y6 s1 d 1 x5 y6 s1 x6 y5 0 d 3 x6 y5 0 f r 0 d 1 source Wire 19, center I modeled the 4" x 1.625" x 0.5" x 0.05" element mounting brackets as U-channels with the YO 8.00 Yagi Optimizer. YO calculated the equivalent cylindrical diameter as 1.28".
88–108 MHz