I modeled the antenna with the AO-Pro 8.01 Antenna Optimizer program. This image shows the antenna geometry.
This shows segmentation detail for the phasing lines and feedpoint. Blue dots indicate analysis-segment boundaries. The lower phasing straps connect to rivets at the underside of the driven-element insulators, while the upper straps connect directly to the elements on top. The rivets electrically lengthen each lower strap by 2". This causes pattern asymmetry visible in the plots below.
The feeders surround a 1"-square boom, which I did not model. The upper and lower feeders are not equidistant from the boom and it may affect their currents.
The directors mount to the boom with conductive brackets. The driven elements are insulated but have metallic brackets that lock the elements into position. I modeled the effect of the brackets with the YO 7.69 Yagi Optimizer program. The electrically equivalent elements are shorter and thicker than the actual elements.
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/B is the ratio of forward power to that directly to the rear.
88.000 MHz: Impedance 168 - j84 ohms
SWR 2.54
Mismatch Loss 0.91 dB
Wire Loss 0.08 dB
Mismatched Gain 6.17 dBd
F/B 17.31 dB
90.000 MHz: Impedance 139 - j32 ohms
SWR 1.73
Mismatch Loss 0.32 dB
Wire Loss 0.04 dB
Mismatched Gain 7.36 dBd
F/B 18.65 dB
92.000 MHz: Impedance 130 + j4 ohms
SWR 1.49
Mismatch Loss 0.17 dB
Wire Loss 0.03 dB
Mismatched Gain 7.69 dBd
F/B 19.95 dB
94.000 MHz: Impedance 137 + j25 ohms
SWR 1.65
Mismatch Loss 0.27 dB
Wire Loss 0.03 dB
Mismatched Gain 7.77 dBd
F/B 21.40 dB
96.000 MHz: Impedance 150 + j28 ohms
SWR 1.80
Mismatch Loss 0.37 dB
Wire Loss 0.03 dB
Mismatched Gain 7.86 dBd
F/B 22.66 dB
98.000 MHz: Impedance 153 + j13 ohms
SWR 1.77
Mismatch Loss 0.35 dB
Wire Loss 0.03 dB
Mismatched Gain 8.10 dBd
F/B 23.12 dB
100.000 MHz: Impedance 133 - j3 ohms
SWR 1.53
Mismatch Loss 0.20 dB
Wire Loss 0.03 dB
Mismatched Gain 8.47 dBd
F/B 22.32 dB
102.000 MHz: Impedance 101 + j5 ohms
SWR 1.17
Mismatch Loss 0.03 dB
Wire Loss 0.04 dB
Mismatched Gain 8.73 dBd
F/B 20.67 dB
104.000 MHz: Impedance 86.4 + j17.2 ohms
SWR 1.22
Mismatch Loss 0.04 dB
Wire Loss 0.03 dB
Mismatched Gain 8.86 dBd
F/B 19.24 dB
106.000 MHz: Impedance 84.7 + j40.2 ohms
SWR 1.59
Mismatch Loss 0.23 dB
Wire Loss 0.04 dB
Mismatched Gain 8.47 dBd
F/B 18.36 dB
108.000 MHz: Impedance 112 + j26 ohms
SWR 1.43
Mismatch Loss 0.14 dB
Wire Loss 0.06 dB
Mismatched Gain 7.74 dBd
F/B 19.12 dB
Calculated
88 98 108 MHz
Gain 6.2 8.1 7.7 dBd (balun loss not included)
F/B 17 23 19 dB
Specified
88 98 108 MHz
Gain 9.4 10.6 10.6 dBd
F/B 18 19 20 dB
Winegard HD6065P Free Space 98.000 MHz 105 6063-T832 wires, inches p = .171875 ; phasing-line equivalent diameter (half of strap width) v = .11 ; feeder wire diameter r = 1.375 ; half of driven-element rivet spacing s = r - .5 ; phasing-line inward bend t = .875 ; phasing-line vertical bend w = 1 ; rivet drop to lower phasing line y = w + t ; lower phasing line midsection z = w + .5 ; reflector shorting strap 1 45 -1 -1 45 1 -1 v aluminum ; feedpoint 1 42 r 0 43.5 r 0 v aluminum 1 43.5 r 0 43.625 1 -1 v aluminum 1 43.625 1 -1 45 1 -1 v aluminum 1 42 -r 0 43.5 -r 0 v aluminum 1 43.5 -r 0 43.625 -1 -1 v aluminum 1 43.625 -1 -1 45 -1 -1 v aluminum 1 0 r 0 0 35.5727 0 .3755 ; 35.875 actual length 1 0 -r 0 0 -35.5727 0 .3755 1 10.5 r 0 10.5 33.0678 0 .3757 ; 33.375 1 10.5 -r 0 10.5 -33.0678 0 .3757 1 21 r 0 21 28.0561 0 .3761 ; 28.375 1 21 -r 0 21 -28.0561 0 .3761 1 31.5 r 0 31.5 25.7997 0 .3765 ; 26.125 1 31.5 -r 0 31.5 -25.7997 0 .3765 1 42 r 0 42 23.7933 0 .3769 ; 24.125 1 42 -r 0 42 -23.7933 0 .3769 1 50.5 -24.878 0 50.5 24.8784 0 .3835 ; 25.5 1 63.5 -24.878 0 63.5 24.8784 0 .3835 ; 25.5 1 80.5 -24.878 0 80.5 24.8784 0 .3835 ; 25.5 1 102 -24.878 0 102 24.8784 0 .3835 ; 25.5 1 125 -22.866 0 125 22.8656 0 .3853 ; 23.5 1 0 r 0 0 r -w p ; rivet 1 0 r -w 0 0 -z p ; reflector shorting strap 1 0 0 -z 0 -r -w p 1 0 r 0 1.875 r 0 p ; top strap 1 1.875 r 0 2 s 0 p 1 2 s 0 2.125 s t p 1 2.125 s t 2.5 0 t p 1 2.5 0 t 8 0 t p 1 8 0 t 8.25 -s t p 1 8.25 -s t 8.375 -s 0 p 1 8.375 -s 0 8.5 -r 0 p 1 8.5 -r 0 10.5 -r 0 p 1 0 -r 0 0 -r -w p ; bottom strap 1 0 -r -w 1.875 -r -w p 1 1.875 -r -w 2 -s -w p 1 2 -s -w 2.125 -s -y p 1 2.125 -s -y 2.5 0 -y p 1 2.5 0 -y 8 0 -y p 1 8 0 -y 8.25 s -y p 1 8.25 s -y 8.375 s -w p 1 8.375 s -w 8.5 r -w p 1 8.5 r -w 10.5 r -w p 1 10.5 r -w 10.5 r 0 p shift x 10.5 1 0 r 0 1.875 r 0 p ; top strap 1 1.875 r 0 2 s 0 p 1 2 s 0 2.125 s t p 1 2.125 s t 2.5 0 t p 1 2.5 0 t 8 0 t p 1 8 0 t 8.25 -s t p 1 8.25 -s t 8.375 -s 0 p 1 8.375 -s 0 8.5 -r 0 p 1 8.5 -r 0 10.5 -r 0 p 1 0 -r 0 0 -r -w p ; bottom strap 1 0 -r -w 1.875 -r -w p 1 1.875 -r -w 2 -s -w p 1 2 -s -w 2.125 -s -y p 1 2.125 -s -y 2.5 0 -y p 1 2.5 0 -y 8 0 -y p 1 8 0 -y 8.25 s -y p 1 8.25 s -y 8.375 s -w p 1 8.375 s -w 8.5 r -w p 1 8.5 r -w 10.5 r -w p 1 10.5 r -w 10.5 r 0 p shift x 21 1 0 r 0 1.875 r 0 p ; top strap 1 1.875 r 0 2 s 0 p 1 2 s 0 2.125 s t p 1 2.125 s t 2.5 0 t p 1 2.5 0 t 8 0 t p 1 8 0 t 8.25 -s t p 1 8.25 -s t 8.375 -s 0 p 1 8.375 -s 0 8.5 -r 0 p 1 8.5 -r 0 10.5 -r 0 p 1 0 -r 0 0 -r -w p ; bottom strap 1 0 -r -w 1.875 -r -w p 1 1.875 -r -w 2 -s -w p 1 2 -s -w 2.125 -s -y p 1 2.125 -s -y 2.5 0 -y p 1 2.5 0 -y 8 0 -y p 1 8 0 -y 8.25 s -y p 1 8.25 s -y 8.375 s -w p 1 8.375 s -w 8.5 r -w p 1 8.5 r -w 10.5 r -w p 1 10.5 r -w 10.5 r 0 p shift x 31.5 1 0 r 0 1.875 r 0 p ; top strap 1 1.875 r 0 2 s 0 p 1 2 s 0 2.125 s t p 1 2.125 s t 2.5 0 t p 1 2.5 0 t 8 0 t p 1 8 0 t 8.25 -s t p 1 8.25 -s t 8.375 -s 0 p 1 8.375 -s 0 8.5 -r 0 p 1 8.5 -r 0 10.5 -r 0 p 1 0 -r 0 0 -r -w p ; bottom strap 1 0 -r -w 1.875 -r -w p 1 1.875 -r -w 2 -s -w p 1 2 -s -w 2.125 -s -y p 1 2.125 -s -y 2.5 0 -y p 1 2.5 0 -y 8 0 -y p 1 8 0 -y 8.25 s -y p 1 8.25 s -y 8.375 s -w p 1 8.375 s -w 8.5 r -w p 1 8.5 r -w 10.5 r -w p 1 10.5 r -w 10.5 r 0 p 1 source Wire 1, center 1 load Impedance load Wire 1, center 0 53.5 Director brackets: 5" x 1.5" x 0.5" x .05" U-channels. Driven element brackets: 3" x 1.375" x .05" flat plates. Elements are 0.5" diameter within the brackets due to reinforcing sheaths. Equivalent lengths and diameters calculated with YO 7.69. Set SWR reference impedance to 87.2 ohms. Disable bent-wire correction.
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Updated July 8, 2007
