Körner 17.5
This is an outdoor receiving antenna for the FM broadcast band designed by Peter Körner. It is a Yagi array with seventeen elements (five reflectors) on a 5.08-meter (200") boom. It uses a folded-dipole driven element for 300-ohm feed or a thick dipole for 75-ohm feed.
This shows four 17.5s stacked horizontally by Kelly Lindman in Sweden.
I modeled the antenna with the AO-Pro 7.02 Antenna Optimizer program. This image shows the antenna geometry.
This image show segmentation detail for the driven element.
Modeling Results
Below are calculated performance figures for a segmentation density of 24 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/B is the ratio of forward power to that directly to the rear. The SWR reference impedance is 300 ohms for the folded dipole and 75 ohms for the dipole.
Folded Dipole Dipole
88.000 MHz: Impedance 267 - j2 ohms 65.6 - j3.3 ohms
SWR 1.12 1.15
Mismatch Loss 0.01 dB 0.02 dB
Wire Loss 0.01 dB 0.01 dB
Mismatched Gain 8.59 dBd 8.58 dBd
F/B 26.42 dB 26.18 dB
90.000 MHz: Impedance 301 + j2 ohms 74.3 - j1.4 ohms
SWR 1.01 1.02
Mismatch Loss 0.00 dB 0.00 dB
Wire Loss 0.01 dB 0.01 dB
Mismatched Gain 8.95 dBd 8.94 dBd
F/B 29.33 dB 29.05 dB
92.000 MHz: Impedance 325 - j8 ohms 80.3 - j2.3 ohms
SWR 1.09 1.08
Mismatch Loss 0.01 dB 0.01 dB
Wire Loss 0.01 dB 0.01 dB
Mismatched Gain 9.31 dBd 9.31 dBd
F/B 30.05 dB 29.80 dB
94.000 MHz: Impedance 330 - j23 ohms 81.9 - j4.0 ohms
SWR 1.13 1.11
Mismatch Loss 0.02 dB 0.01 dB
Wire Loss 0.01 dB 0.01 dB
Mismatched Gain 9.68 dBd 9.68 dBd
F/B 29.94 dB 29.69 dB
96.000 MHz: Impedance 322 - j25 ohms 80.1 - j3.0 ohms
SWR 1.11 1.08
Mismatch Loss 0.01 dB 0.01 dB
Wire Loss 0.01 dB 0.01 dB
Mismatched Gain 10.07 dBd 10.07 dBd
F/B 30.99 dB 30.68 dB
98.000 MHz: Impedance 319 - j15 ohms 79.3 + j1.1 ohms
SWR 1.08 1.06
Mismatch Loss 0.01 dB 0.00 dB
Wire Loss 0.02 dB 0.01 dB
Mismatched Gain 10.43 dBd 10.43 dBd
F/B 33.78 dB 33.47 dB
100.000 MHz: Impedance 323 - j17 ohms 80.6 + j2.4 ohms
SWR 1.10 1.08
Mismatch Loss 0.01 dB 0.01 dB
Wire Loss 0.02 dB 0.02 dB
Mismatched Gain 10.72 dBd 10.72 dBd
F/B 33.71 dB 33.97 dB
102.000 MHz: Impedance 293 - j20 ohms 73.2 + j1.6 ohms
SWR 1.08 1.03
Mismatch Loss 0.01 dB 0.00 dB
Wire Loss 0.03 dB 0.03 dB
Mismatched Gain 10.85 dBd 10.85 dBd
F/B 30.36 dB 30.63 dB
104.000 MHz: Impedance 286 + j45 ohms 68.0 + j18.1 ohms
SWR 1.18 1.31
Mismatch Loss 0.03 dB 0.08 dB
Wire Loss 0.04 dB 0.04 dB
Mismatched Gain 10.66 dBd 10.59 dBd
F/B 32.32 dB 32.35 dB
106.000 MHz: Impedance 333 - j35 ohms 83.9 + j3.6 ohms
SWR 1.16 1.13
Mismatch Loss 0.03 dB 0.02 dB
Wire Loss 0.07 dB 0.06 dB
Mismatched Gain 10.03 dBd 10.01 dB
F/B 36.34 dB 36.91 dB
108.000 MHz: Impedance 293 - j56 ohms 75.8 - j3.5 ohms
SWR 1.21 1.05
Mismatch Loss 0.04 dB 0.00 dB
Wire Loss 0.14 dB 0.13 dB
Mismatched Gain 9.21 dBd 9.20 dBd
F/B 24.15 dB 24.20 dB
Patterns
The following plots compare the pattern of Kelly Lindman's four-Yagi array with that of a single Yagi.
All patterns are for the folded dipole. The dipole patterns are nearly identical.
Antenna File
Körner 17.5 Yagi Free Space Symmetric 98.000 MHz 24 6063-T832 wires, meters d1 = 1.3 / 2 d2 = 1.316 / 2 d3 = 1.31 / 2 d4 = 1.26 / 2 d5 = 1.272 / 2 d6 = 1.252 / 2 d7 = 1.25 / 2 d8 = 1.24 / 2 d9 = 1.228 / 2 d10 = 1.25 / 2 d11 = 1.186 / 2 p1 = .66 p2 = .76 p3 = 1.002 p4 = 1.306 p5 = 1.6 p6 = 2.01 p7 = 2.46 p8 = 3.052 p9 = 3.703 p10 = 4.352 p11 = 5.08 z1 = .37 z2 = .73 x1 = .04 x2 = .09 dp = .59 r0 = 1.98 / 2 r1 = 1.97 / 2 r2 = 1.9 / 2 a = .775 b = .79 d = 10mm shift x -2.54 1 0 -r0 0 0 r0 0 d 1 x1 -r1 z1 x1 r1 z1 d 1 x1 -r1 -z1 x1 r1 -z1 d 1 x2 -r2 z2 x2 r2 z2 d 1 x2 -r2 -z2 x2 r2 -z2 d 1 dp -a -.02 dp a -.02 d ; folded dipole for 300-ohm feed (24 wires total) 1 dp -a .02 dp a .02 d 1 dp -b -.01 dp -b .01 d 1 dp b -.01 dp b .01 d 1 dp -b -.01 dp -a -.02 d 1 dp -b .01 dp -a .02 d 1 dp b -.01 dp a -.02 d 1 dp b .01 dp a .02 d ; 1 dp -.79 0 dp .79 0 3cm ; thick dipole for 75-ohm feed (17 wires total) 1 p1 -d1 0 p1 d1 0 d 1 p2 -d2 0 p2 d2 0 d 1 p3 -d3 0 p3 d3 0 d 1 p4 -d4 0 p4 d4 0 d 1 p5 -d5 0 p5 d5 0 d 1 p6 -d6 0 p6 d6 0 d 1 p7 -d7 0 p7 d7 0 d 1 p8 -d8 0 p8 d8 0 d 1 p9 -d9 0 p9 d9 0 d 1 p10 -d10 0 p10 d10 0 d 1 p11 -d11 0 p11 d11 0 d 1 source Wire 6, center
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Updated July 8, 2007
