The Channel Master Stereo Probe 9, model number 3025 (previously 4408), is an outdoor receiving antenna for the FM broadcast band. It is a Log-Yagi array with nine elements on a 138″ boom. Four folded elements are driven.
I modeled the antenna with the AO-Pro 8.50 Antenna Optimizer program. This image shows the antenna geometry.
This shows segmentation detail for the phasing lines. Blue dots indicate analysis segments. The red dot is the feedpoint. The phasing line is bowed inward to avoid the mast.
Ken Wetzel uses this Probe 9 at Ridgecrest, California.
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 124 - j148 ohms
SWR 3.10
Mismatch Loss 1.32 dB
Wire Loss 0.05 dB
Mismatched Gain 6.87 dBd
F/R 15.94 dB
93.000 MHz: Impedance 354 + j78 ohms
SWR 1.34
Mismatch Loss 0.09 dB
Wire Loss 0.02 dB
Mismatched Gain 8.67 dBd
F/R 18.47 dB
98.000 MHz: Impedance 398 - j42 ohms
SWR 1.36
Mismatch Loss 0.10 dB
Wire Loss 0.01 dB
Mismatched Gain 8.77 dBd
F/R 20.57 dB
103.000 MHz: Impedance 266 + j111 ohms
SWR 1.50
Mismatch Loss 0.18 dB
Wire Loss 0.02 dB
Mismatched Gain 9.03 dBd
F/R 16.75 dB
108.000 MHz: Impedance 577 + j148 ohms
SWR 2.09
Mismatch Loss 0.58 dB
Wire Loss 0.03 dB
Mismatched Gain 8.07 dBd
F/R 12.84 dB
Probe 9 Free Space 98 MHz 77 6063-T832 wires, inches p1 = 0 ; element positions p2 = 20 p23 = 30 p3 = 40 p34 = 50 p4 = 60 p4f = 61.375 ; feedpoint p5 = 75 p6 = 90 p7 = 105 p8 = 120 p9 = 135 a1 = 27.25 ; DE1 overall length a2 = a1 - 1 ; start of end curve a3 = a1 - 3 ; end of 0.5"-diameter tubing b1 = 31.75 ; DE2 b2 = b1 - 1 b3 = b1 - 3 c1 = 34.25 ; DE3 c2 = c1 - 1 c3 = c1 - 3 d1 = 37.25 ; DE4 d2 = d1 - 1 d3 = d1 - 3 d = .375 ; element diameter c = .5 ; folded dipole end diameter m = 1.75 ; director mounting bracket halfwidth b = 1 ; equivalent diameter of mounting brackets s = 1.125 ; phasing-line spacing t = .375 ; phasing-line spacing near mast h = 1.25 ; folded dipole halfheight j = h + .5 ; rise at adjustable phasing-line joint between DE2 & DE3 shift x -67.5 1 p1 -d1 0 p1 -d2 h c 1 p1 -d2 h p1 -d3 h c 1 p1 -d3 h p1 -2 h d 1 p1 -2 h p1 2 h b 1 p1 2 h p1 d3 h d 1 p1 d3 h p1 d2 h c 1 p1 d2 h p1 d1 0 c 1 p1 -d1 0 p1 -d2 -h c 1 p1 -d2 -h p1 -d3 -h c 1 p1 -d3 -h p1 -s -h d 1 p1 s -h p1 d3 -h d 1 p1 d3 -h p1 d2 -h c 1 p1 d2 -h p1 d1 0 c 1 p2 -c1 0 p2 -c2 h c 1 p2 -c2 h p2 -c3 h c 1 p2 -c3 h p2 -s h d 1 p2 s h p2 c3 h d 1 p2 c3 h p2 c2 h c 1 p2 c2 h p2 c1 0 c 1 p2 -c1 0 p2 -c2 -h c 1 p2 -c2 -h p2 -c3 -h c 1 p2 -c3 -h p2 -s -h d 1 p2 s -h p2 c3 -h d 1 p2 c3 -h p2 c2 -h c 1 p2 c2 -h p2 c1 0 c 1 p3 -b1 0 p3 -b2 h c 1 p3 -b2 h p3 -b3 h c 1 p3 -b3 h p3 -s h d 1 p3 s h p3 b3 h d 1 p3 b3 h p3 b2 h c 1 p3 b2 h p3 b1 0 c 1 p3 -b1 0 p3 -b2 -h c 1 p3 -b2 -h p3 -b3 -h c 1 p3 -b3 -h p3 -s -h d 1 p3 s -h p3 b3 -h d 1 p3 b3 -h p3 b2 -h c 1 p3 b2 -h p3 b1 0 c 1 p4 -a1 0 p4 -a2 h c 1 p4 -a2 h p4 -a3 h c 1 p4 -a3 h p4 -s h d 1 p4 -s h p4f -s h .5 ; equiv diam = half the plate width 1 p4f -s h p4f s h #22 copper ; feedpoint 1 p4 s h p4f s h .5 ; equiv diam = half the plate width 1 p4 s h p4 a3 h d 1 p4 a3 h p4 a2 h c 1 p4 a2 h p4 a1 0 c 1 p4 -a1 0 p4 -a2 -h c 1 p4 -a2 -h p4 -a3 -h c 1 p4 -a3 -h p4 -s -h d 1 p4 s -h p4 a3 -h d 1 p4 a3 -h p4 a2 -h c 1 p4 a2 -h p4 a1 0 c 1 p4 s -h p34 t -h d 1 p34 t -h p3 s -h d 1 p4 -s -h p34 -t -h d 1 p34 -t -h p3 -s -h d 1 p3 s h p23 s j d 1 p23 s j p2 s h d 1 p3 -s h p23 -s j d 1 p23 -s j p2 -s h d 1 p2 s -h p1 s -h .25 1 p2 -s -h p1 -s -h .25 1 p5 -25 0 p5 -m 0 d 1 p5 -m 0 p5 m 0 b 1 p5 m 0 p5 25 0 d 1 p6 -24.5 0 p6 -m 0 d 1 p6 -m 0 p6 m 0 b 1 p6 m 0 p6 24.5 0 d 1 p7 -24.5 0 p7 -m 0 d 1 p7 -m 0 p7 m 0 b 1 p7 m 0 p7 24.5 0 d 1 p8 -24.5 0 p8 -m 0 d 1 p8 -m 0 p8 m 0 b 1 p8 m 0 p8 24.5 0 d 1 p9 -24 0 p9 -m 0 d 1 p9 -m 0 p9 m 0 b 1 p9 m 0 p9 24 0 d 1 source Wire 42, center Mounting bracket equivalent diameter calculated with the YO 7.66 Yagi Optimizer. Disable bent-wire correction.
88–108 MHz