The Antennacraft FM10 is a log-Yagi array with ten elements on a 117″ boom. Three of the elements are driven.
I modeled the antenna with the AO 9.67 Antenna Optimizer program. This image shows the antenna geometry.
This shows segmentation detail for the phasing lines and feedpoint. 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.
Joe Roberts used this FM10 in the late 1970s at Wilbraham, Massachusetts.
Calculated performance is for 28 analysis segments per conductor halfwave with additional segments for the phasing lines. Forward gain includes mismatch and conductor losses. 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
88 188-j80 1.77 0.35 0.03 6.80 16.24
89 210-j60 1.53 0.20 0.03 7.00 20.30
90 230-j48 1.38 0.11 0.02 7.12 23.05
91 251-j43 1.27 0.06 0.02 7.21 23.89
92 271-j44 1.20 0.04 0.02 7.31 24.16
93 290-j52 1.20 0.04 0.02 7.38 24.37
94 308-j69 1.26 0.06 0.02 7.45 24.64
95 322-j95 1.37 0.11 0.02 7.50 24.06
96 324-j130 1.52 0.19 0.02 7.53 22.14
97 312-j168 1.72 0.32 0.02 7.53 20.60
98 284-j200 1.96 0.48 0.02 7.49 19.34
99 245-j219 2.25 0.69 0.02 7.41 18.26
100 205-j223 2.56 0.93 0.02 7.31 17.32
101 169-j215 2.90 1.18 0.02 7.20 16.43
102 142-j200 3.21 1.40 0.02 7.11 15.74
103 123-j181 3.45 1.57 0.02 7.05 15.17
104 111-j162 3.57 1.65 0.03 7.07 14.74
105 107-j144 3.52 1.62 0.03 7.20 14.49
106 111-j131 3.28 1.45 0.03 7.45 14.50
107 121-j128 2.99 1.24 0.03 7.72 14.80
108 129-j144 2.96 1.22 0.03 7.79 15.54
Antennacraft FM10 Free Space 98.000 MHz 50 6063-T832 wires, inches de1 = 14.625 ; driven element locations de2 = 27 de3 = 39.375 d = .11 ; phasing-line diameter r = 3 / 2 ; half of rivet spacing (insulated elements) h = 12.375 / 2 ; half of DE spacing y1 = r * (1 - 3.375 / h) ; y at first phasing-line bend y2 = r * (1 - 3.875 / h) ; y at second bend y3 = -y2 ; y at third bend y4 = -y1 ; y at fourth bend x1 = de1 + 3.375 ; x at first phasing-line bend, rear line x2 = de1 + 3.875 ; x at second bend x3 = de2 - 3.875 ; x at third bend x4 = de2 - 3.375 ; x at fourth bend x5 = de2 + 3.375 ; x at first phasing-line bend, forward line x6 = de2 + 3.875 ; x at second bend x7 = de3 - 3.875 ; x at third bend x8 = de3 - 3.375 ; x at fourth bend s = .5 / 2 ; half of phasing-line crossover spacing b = .75 ; feedpoint bolt length 1 0.0000 -32.8750 0.0000 0.0000 -2.0000 0.0000 0.3750 1 0.0000 -2.0000 0.0000 0.0000 2.0000 0.0000 1.28 1 0.0000 2.0000 0.0000 0.0000 32.8750 0.0000 0.3750 1 14.6250 -29.5000 0.0000 14.6250 -r 0.0000 0.3750 1 14.6250 r 0.0000 14.6250 29.5000 0.0000 0.3750 1 27.0000 -28.2500 0.0000 27.0000 -r 0.0000 0.3750 1 27.0000 r 0.0000 27.0000 28.2500 0.0000 0.3750 1 39.3750 -21.8750 0.0000 39.3750 -r 0.0000 0.3750 1 39.3750 r 0.0000 39.3750 21.8750 0.0000 0.3750 1 43.1250 -25.0000 -1.9375 43.1250 -2.0000 -1.9375 0.3750 1 43.1250 -2.0000 -1.9375 43.1250 2.0000 -1.9375 1.28 1 43.1250 2.0000 -1.9375 43.1250 25.0000 -1.9375 0.3750 1 53.7500 -24.0000 0.0000 53.7500 -2.0000 0.0000 0.3750 1 53.7500 -2.0000 0.0000 53.7500 2.0000 0.0000 1.28 1 53.7500 2.0000 0.0000 53.7500 24.0000 0.0000 0.3750 1 65.2500 -24.0000 0.0000 65.2500 -2.0000 0.0000 0.3750 1 65.2500 -2.0000 0.0000 65.2500 2.0000 0.0000 1.28 1 65.2500 2.0000 0.0000 65.2500 24.0000 0.0000 0.3750 1 83.7500 -24.0000 0.0000 83.7500 -2.0000 0.0000 0.3750 1 83.7500 -2.0000 0.0000 83.7500 2.0000 0.0000 1.28 1 83.7500 2.0000 0.0000 83.7500 24.0000 0.0000 0.3750 1 100.3750 -24.0000 0.0000 100.3750 -2.0000 0.0000 0.3750 1 100.3750 -2.0000 0.0000 100.3750 2.0000 0.0000 1.28 1 100.3750 2.0000 0.0000 100.3750 24.0000 0.0000 0.3750 1 117.3750 -24.0000 0.0000 117.3750 -2.0000 0.0000 0.3750 1 117.3750 -2.0000 0.0000 117.3750 2.0000 0.0000 1.28 1 117.3750 2.0000 0.0000 117.3750 24.0000 0.0000 0.3750 4 de1 r 0 x1 y1 0 d 1 x1 y1 0 x2 y2 -s d 10 x2 y2 -s x3 y3 -s d 1 x3 y3 -s x4 y4 0 d 4 x4 y4 0 de2 -r 0 d 4 de1 -r 0 x1 -y1 0 d 1 x1 -y1 0 x2 -y2 s d 10 x2 -y2 s x3 -y3 s d 1 x3 -y3 s x4 -y4 0 d 4 x4 -y4 0 de2 r 0 d 4 de2 r 0 x5 y1 0 d 1 x5 y1 0 x6 y2 s d 8 x6 y2 s x7 y3 s d 1 x7 y3 s x8 y4 0 d 4 x8 y4 0 de3 -r 0 d 4 de2 -r 0 x5 -y1 0 d 1 x5 -y1 0 x6 -y2 -s d 8 x6 -y2 -s x7 -y3 -s d 1 x7 -y3 -s x8 -y4 0 d 4 x8 -y4 0 de3 r 0 d 1 de3 -r 0 de3 -r -b .125 zinc 1 de3 -r -b de3 r -b #16 copper 1 de3 r 0 de3 r -b .125 zinc 1 source Wire 49, center I modeled the 4" x 1.625" x 0.5" x 0.05" bracket as a U channel with YO 8.00 to get the 1.28" equivalent diameter of the inner taper section for the parasitic elements.
88–108 MHz