Peter Körner in Lund, Sweden, designed this Yagi array. It has a boom length of 2.05 m (81″), nine elements, three reflectors, and a horizontal folded dipole.
Unlike log-Yagis, the 9.2 has no phasing lines that can induce current in the boom and degrade the pattern. The red dot indicates the 300Ω feedpoint.
The horizontal folded dipole is unusually long and the two conductor currents differ, as does their coupling to the first director. Because of these factors, conductor spacing strongly affects antenna performance and can be optimized. It provides only a weak degree of freedom for a vertical folded dipole.
I modeled the antenna with the AO 9.57 Antenna Optimizer program using 28 analysis segments per conductor 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
88 290+j5 1.04 0.00 0.01 6.19 27.45
89 297-j2 1.01 0.00 0.01 6.24 30.39
90 302-j9 1.03 0.00 0.01 6.31 33.65
91 303-j15 1.05 0.00 0.01 6.38 34.04
92 302-j20 1.07 0.00 0.01 6.46 33.98
93 299-j23 1.08 0.01 0.01 6.55 33.12
94 294-j24 1.09 0.01 0.01 6.64 32.23
95 289-j23 1.09 0.01 0.01 6.74 31.58
96 283-j19 1.09 0.01 0.01 6.84 31.13
97 278-j15 1.10 0.01 0.01 6.95 30.84
98 273-j10 1.11 0.01 0.01 7.05 30.73
99 268-j4 1.12 0.01 0.01 7.16 30.71
100 263+j3 1.14 0.02 0.01 7.26 30.62
101 258+j11 1.17 0.03 0.01 7.35 30.71
102 253+j20 1.21 0.04 0.01 7.41 30.61
103 247+j28 1.24 0.05 0.02 7.46 30.43
104 241+j33 1.29 0.07 0.02 7.46 29.87
105 229+j42 1.37 0.11 0.03 7.39 29.17
106 213+j55 1.50 0.18 0.03 7.20 28.08
107 195+j79 1.71 0.31 0.04 6.82 26.81
108 191+j120 1.94 0.47 0.06 6.23 25.48
This shows how ground proximity affects F/R at 1° elevation angle for various antenna heights.
Körner 9.2 Free Space Symmetric 98 MHz 12 6063-T832 wires, meters z = 0.53 ; reflector height r0 = 0.982 ; reflector half-lengths r1 = 0.911 rp = 0.05 ; outer reflector positions de = 0.8 ; driven element half-length d1 = 0.657 ; director half-lengths d2 = 0.657 d3 = 0.647 d4 = 0.621 d5 = 0.562 de1 = 0.44 ; driven element positions de2 = 0.54 d1p = 0.65 ; director positions d2p = 0.79 d3p = 1.07 d4p = 1.47 d5p = 2.05 1 rp -r1 z rp r1 z .012 1 0 -r0 0 0 r0 0 .012 1 rp -r1 -z rp r1 -z .012 1 de1 -de 0 de1 de 0 .012 1 de2 -de 0 de2 de 0 .012 1 de1 de 0 de2 de 0 .012 1 de1 -de 0 de2 -de 0 .012 1 d1p -d1 0 d1p d1 0 .012 1 d2p -d2 0 d2p d2 0 .012 1 d3p -d3 0 d3p d3 0 .012 1 d4p -d4 0 d4p d4 0 .012 1 d5p -d5 0 d5p d5 0 .012 1 source Wire 5, center
The following table shows the largest performance degradation over 88, 93, 98, 103, and 108 MHz in dB when altering a symbol value by Tol.
Symbol Tol Gain F/R
z 0.0010 0.00 0.04
r0 0.0005 0.00 0.02
r1 0.0005 0.00 0.09
rp 0.0010 0.00 0.03
de 0.0005 0.00 0.02
d1 0.0005 0.03 0.04
d2 0.0005 0.03 0.11
d3 0.0005 0.08 0.13
d4 0.0005 0.02 0.13
d5 0.0005 0.00 0.03
de1 0.0010 0.00 0.03
de2 0.0010 0.01 0.04
d1p 0.0010 0.01 0.04
d2p 0.0010 0.01 0.06
d3p 0.0010 0.01 0.06
d4p 0.0010 0.00 0.02
d5p 0.0010 0.00 0.03
John Faulkner erected this 9.2 in Skegness, Lincolnshire, England. It rotates in azimuth and polarization here.
This is Balazs Benko's 9.2 in Budapest, Hungary.
Petr Vozár erected this 9.2 near Javornik, Czech Republic.
This shows Georgiy Markiev's vertical stack in Petrozavodsk, Russia. The antenna came down in a wind storm.
Paul Z. in White Plains, New York, had this 9.2 shipped from Germany.
Glenn Davis built this 9.2 with spliced elements and custom element mounts in Hutto, Texas.
Dawid Dobruchowski built this 9.2 in Topólka, Kuyavia, Poland. It 20 meters up on his farm silo. It rotates here.
88–108 MHz