The Finco FM-5 is a dual-driven Yagi with ten elements on a 117″ boom. It was once manufactured by the Finney Company.
I modeled the antenna with the AO-Pro 8.50 Antenna Optimizer program. This image shows the antenna geometry.
This shows the segmentation of the driven elements and phasing line. Blue dots mark analysis segments. The red dot is the feedpoint.
Mike Bugaj used this FM-5 in the early 1970s at Anaheim, California.
A Finco instruction sheet is here.
Below are calculated performance figures for a segmentation density of 40 segments per halfwave. Mismatch loss is due to SWR. Wire loss is due to conductor resistance. Mismatched gain is forward gain including wire and mismatch losses. F/R is the ratio of forward power to that of the worst backlobe in the rear half-plane. The SWR reference impedance is 300Ω.
88.000 MHz: Impedance 221 + j101 ohms
SWR 1.64
Mismatch Loss 0.26 dB
Wire Loss 0.01 dB
Mismatched Gain 7.04 dBd
F/R 22.50 dB
93.000 MHz: Impedance 280 + j158 ohms
SWR 1.72
Mismatch Loss 0.32 dB
Wire Loss 0.01 dB
Mismatched Gain 7.47 dBd
F/R 18.14 dB
98.000 MHz: Impedance 303 + j5 ohms
SWR 1.02
Mismatch Loss 0.00 dB
Wire Loss 0.02 dB
Mismatched Gain 8.42 dBd
F/R 16.24 dB
103.000 MHz: Impedance 130 + j53 ohms
SWR 2.39
Mismatch Loss 0.80 dB
Wire Loss 0.02 dB
Mismatched Gain 7.91 dBd
F/R 15.83 dB
108.000 MHz: Impedance 129 + j6 ohms
SWR 2.32
Mismatch Loss 0.75 dB
Wire Loss 0.05 dB
Mismatched Gain 7.06 dBd
F/R 18.85 dB
Finco FM-5 Free Space 98 MHz 45 6063-T832 wires, inches rp = 0 de1p = 16 de2p = 33 d1p = 45 d2p = 57 d3p = 69 d4p = 81 d5p = 93 d6p = 105 d7p = 117 r = 34.25 ; Actual length, 35 de1 = 30 de2 = 23 d1 = 24.75 ; Actual length, 25.5 d2 = 24.75 ; Actual length, 25.5 d3 = 24.75 ; Actual length, 25.5 d4 = 23.75 ; Actual length, 24.5 d5 = 23.75 ; Actual length, 24.5 d6 = 22.75 ; Actual length, 23.5 d7 = 22.75 ; Actual length, 23.5 de1s = 10 de2s = 12 d = .43 ; Actual diameter, .375 w = .125 x1 = 27.5 xm = 29.5 x2 = 31.5 f = 23.75 shift x -58 ; For better geometry display 1 rp -r 0 rp r 0 d 1 de1p -de1 -2 de1p -de1s -2 .375 1 de1p -de1s -2 de1p -1 -2 .375 1 de1p 1 -2 de1p de1s -2 .375 1 de1p de1s -2 de1p de1 -2 .375 1 de1p -de1 0 de1p -de1s 0 .375 1 de1p -de1s 0 de1p -2.3125 0 .375 1 de1p -2.3125 0 de1p 2.3125 0 1.1 ; Equivalent to 0.5" tubing + bracket 1 de1p 2.3125 0 de1p de1s 0 .375 1 de1p de1s 0 de1p de1 0 .375 1 de1p -de1 -2 de1p -de1 0 .375 1 de1p de1 -2 de1p de1 0 .375 1 de1p -de1s -2 de1p -de1s 0 .375 1 de1p de1s -2 de1p de1s 0 .375 1 de2p -de2 -2 de2p -de2s -2 .375 1 de2p -de2s -2 de2p -1 -2 .375 1 de2p 1 -2 de2p de2s -2 .375 1 de2p de2s -2 de2p de2 -2 .375 1 de2p -de2 0 de2p -de2s 0 .375 1 de2p -de2s 0 de2p -2.3125 0 .375 1 de2p -2.3125 0 de2p 2.3125 0 1.1 1 de2p 2.3125 0 de2p de2s 0 .375 1 de2p de2s 0 de2p de2 0 .375 1 de2p -de2 -2 de2p -de2 0 .375 1 de2p de2 -2 de2p de2 0 .375 1 de2p -de2s -2 de2p -de2s 0 .375 1 de2p de2s -2 de2p de2s 0 .375 1 d1p -d1 0 d1p d1 0 d 1 d2p -d2 0 d2p d2 0 d 1 d3p -d3 0 d3p d3 0 d 1 d4p -d4 0 d4p d4 0 d 1 d5p -d5 0 d5p d5 0 d 1 d6p -d6 0 d6p d6 0 d 1 d7p -d7 0 d7p d7 0 d 1 de1p -1 -2 f -1 -2 w ; Transmission line 1 f -1 -2 x1 -1 -2 w 1 x1 -1 -2 xm 0 -1.125 w 1 xm 0 -1.125 x2 1 -2 w 1 x2 1 -2 de2p 1 -2 w 1 de1p 1 -2 f 1 -2 w 1 f 1 -2 x1 1 -2 w 1 x1 1 -2 xm 0 -2.875 w 1 xm 0 -2.875 x2 -1 -2 w 1 x2 -1 -2 de2p -1 -2 w 1 f 1 -2 f -1 -2 w 1 source Wire 45, center This models the Finco FM-5 receiving antenna for the FM broadcast band. Each parasitic element half-length was shortened by 0.75" to account for the inner 0.5"-diameter reinforcement tubing section, the rectangular element-mounting bracket, and the 1"-square boom. The bracket and reinforcement sections increase element effective diameter to 0.43". The driven elements are modeled using actual lengths and diameters, plus an inner 1.1"-diameter section equivalent to the reinforcement section and mounting bracket. All corrections and equivalents were computed with the YO Yagi Optimizer program. Disable bent-wire correction.
88–108 MHz