The Antennacraft FM10 is a Log-Yagi array with ten elements on a 120″ boom. Three of the elements are driven.
I modeled the antenna with the AO 9.50 Antenna Optimizer program. This image shows the antenna geometry.
This shows segmentation detail for the phasing lines and feedpoint. 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 figures are for a segmentation density of 50 segments per halfwave. 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
88 198 - j74 1.67 0.28 0.03 6.89 18.52
89 217 - j56 1.47 0.16 0.03 7.05 22.28
90 236 - j45 1.34 0.09 0.02 7.16 23.78
91 255 - j39 1.24 0.05 0.02 7.26 24.10
92 275 - j40 1.18 0.03 0.02 7.35 24.27
93 296 - j48 1.18 0.03 0.02 7.43 24.54
94 316 - j67 1.25 0.05 0.02 7.51 24.72
95 330 - j97 1.38 0.11 0.02 7.56 22.60
96 330 - j136 1.55 0.21 0.02 7.58 20.96
97 314 - j176 1.77 0.35 0.02 7.57 19.61
98 280 - j208 2.03 0.53 0.02 7.52 18.46
99 237 - j218 2.29 0.72 0.11 7.37 17.49
100 196 - j219 2.61 0.96 0.12 7.26 16.61
101 162 - j207 2.93 1.20 0.12 7.15 15.86
102 137 - j190 3.21 1.40 0.12 7.07 15.23
103 120 - j170 3.40 1.54 0.12 7.04 14.74
104 112 - j150 3.45 1.57 0.12 7.11 14.44
105 111 - j133 3.29 1.46 0.13 7.30 14.32
106 120 - j124 3.00 1.25 0.14 7.57 14.53
107 131 - j133 2.82 1.12 0.15 7.74 15.16
108 121 - j162 3.30 1.46 0.19 7.39 16.40
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 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 1.1 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 1.1 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 1.1 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 1.1 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 1.1 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 1.1 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 1.1 1 117.3750 2.0000 0.0000 117.3750 24.0000 0.0000 0.3750 1 de1 r 0 x1 y1 0 d 1 x1 y1 0 x2 y2 -s d 1 x2 y2 -s x3 y3 -s d 1 x3 y3 -s x4 y4 0 d 1 x4 y4 0 de2 -r 0 d 1 de1 -r 0 x1 -y1 0 d 1 x1 -y1 0 x2 -y2 s d 1 x2 -y2 s x3 -y3 s d 1 x3 -y3 s x4 -y4 0 d 1 x4 -y4 0 de2 r 0 d 1 de2 r 0 x5 y1 0 d 1 x5 y1 0 x6 y2 s d 1 x6 y2 s x7 y3 s d 1 x7 y3 s x8 y4 0 d 1 x8 y4 0 de3 -r 0 d 1 de2 -r 0 x5 -y1 0 d 1 x5 -y1 0 x6 -y2 -s d 1 x6 -y2 -s x7 -y3 -s d 1 x7 -y3 -s x8 -y4 0 d 1 x8 -y4 0 de3 r 0 d 1 de3 -r 0.0000 de3 -r -0.7500 .125 steel 1 de3 -r -0.7500 de3 r -0.7500 #18 copper 1 de3 r 0.0000 de3 r -0.7500 .125 steel 1 source Wire 49, center The 4" x 1.625" x 1/32" bracket was modeled as a U channel by YO to get the 1.1" equivalent diameter of the inner taper section for the parasitic elements. The steel wires near the feedpoint model the terminal bolts.
88–108 MHz