Triax FM 5
The Triax FM 5 is a five-element Yagi for the FM broadcast band made in Europe. It has a 1.9-meter (74") boom.
I modeled the antenna with the AO 7.05 Antenna Optimizer program. This image shows the segmentation detail. Blue dots indicate analysis-segment boundaries. The red dot indicates the feedpoint. I did not model the mounting brackets.
Modeling Results
Below are calculated performance figures for a segmentation density of 30 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.
88.000 MHz: Impedance 170 - j2 ohms
SWR 1.77
Mismatch Loss 0.35 dB
Wire Loss 0.01 dB
Mismatched Gain 5.25 dBd
F/B 7.06 dB
90.000 MHz: Impedance 222 + j45 ohms
SWR 1.42
Mismatch Loss 0.13 dB
Wire Loss 0.01 dB
Mismatched Gain 5.78 dBd
F/B 10.52 dB
92.000 MHz: Impedance 274 + j72 ohms
SWR 1.31
Mismatch Loss 0.08 dB
Wire Loss 0.01 dB
Mismatched Gain 5.88 dBd
F/B 12.90 dB
94.000 MHz: Impedance 323 + j85 ohms
SWR 1.33
Mismatch Loss 0.09 dB
Wire Loss 0.01 dB
Mismatched Gain 5.87 dBd
F/B 13.44 dB
96.000 MHz: Impedance 370 + j86 ohms
SWR 1.39
Mismatch Loss 0.12 dB
Wire Loss 0.01 dB
Mismatched Gain 5.87 dBd
F/B 12.85 dB
98.000 MHz: Impedance 409 + j68 ohms
SWR 1.44
Mismatch Loss 0.14 dB
Wire Loss 0.01 dB
Mismatched Gain 5.92 dBd
F/B 12.10 dB
100.000 MHz: Impedance 425 + j32 ohms
SWR 1.43
Mismatch Loss 0.14 dB
Wire Loss 0.01 dB
Mismatched Gain 6.04 dBd
F/B 11.60 dB
102.000 MHz: Impedance 400 - j2 ohms
SWR 1.33
Mismatch Loss 0.09 dB
Wire Loss 0.01 dB
Mismatched Gain 6.26 dBd
F/B 11.61 dB
104.000 MHz: Impedance 337 + j6 ohms
SWR 1.12
Mismatch Loss 0.01 dB
Wire Loss 0.01 dB
Mismatched Gain 6.60 dBd
F/B 12.55 dB
106.000 MHz: Impedance 279 + j88 ohms
SWR 1.37
Mismatch Loss 0.10 dB
Wire Loss 0.02 dB
Mismatched Gain 6.94 dBd
F/B 15.90 dB
108.000 MHz: Impedance 337 + j271 ohms
SWR 2.31
Mismatch Loss 0.74 dB
Wire Loss 0.04 dB
Mismatched Gain 6.83 dBd
F/B 29.85 dB
Patterns
Antenna File
Triax FM 5 Free Space Symmetric 98 MHz 15 6063-T832 wires, meters 1 0 -0.79 0 0 0.79 0 .01 1 0.76 -.7225 -.03 0.76 .7225 -.03 .01 1 0.76 .27 .03 0.76 .7225 .03 .01 1 0.76 -.7425 -.01 0.76 -.7425 .01 .01 1 0.76 .7425 -.01 0.76 .7425 .01 .01 1 0.76 -.7425 -.01 0.76 -.7225 -.03 .01 1 0.76 -.7425 .01 0.76 -.7225 .03 .01 1 0.76 .7425 -.01 0.76 .7225 -.03 .01 1 0.76 .7425 .01 0.76 .7225 .03 .01 1 0.76 -.7225 .03 0.76 -.27 .03 .01 1 0.76 -.27 .03 0.76 0 -.015 .01 1 0.76 .27 .03 0.76 0 -.015 .01 1 0.913 -0.635 0 0.913 0.635 0 .01 1 1.323 -0.635 0 1.323 0.635 0 .01 1 1.873 -0.62 0 1.873 0.62 0 .01 1 source Wire 2, center
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Updated July 8, 2007
