Antenna Performance Specialities APS-13
The Antenna Performance Specialties APS-13 is an outdoor receiving antenna for the FM broadcast band. It is a Log-Yagi array with thirteen elements on a 200" boom. Five of the elements are driven. A shorted transmission line terminates at a passive reflector.
I modeled the antenna with the AO-Pro 7.03 Antenna Optimizer program. This image shows the antenna geometry.
This image shows segmentation detail for the phasing lines that interconnect the driven elements.
Modeling Results
Below are calculated performance figures for a segmentation density of 80 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. Balun loss is not included.
88.000 MHz: Impedance 182 + j88 ohms
SWR 1.86
Mismatch Loss 0.41 dB
Wire Loss 0.10 dB
Mismatched Gain 8.44 dBd
F/B 31.77 dB
90.000 MHz: Impedance 160 + j70 ohms
SWR 2.01
Mismatch Loss 0.52 dB
Wire Loss 0.06 dB
Mismatched Gain 8.51 dBd
F/B 29.99 dB
92.000 MHz: Impedance 190 + j86 ohms
SWR 1.78
Mismatch Loss 0.36 dB
Wire Loss 0.05 dB
Mismatched Gain 8.80 dBd
F/B 30.49 dB
94.000 MHz: Impedance 223 + j75 ohms
SWR 1.51
Mismatch Loss 0.18 dB
Wire Loss 0.04 dB
Mismatched Gain 9.12 dBd
F/B 33.64 dB
96.000 MHz: Impedance 236 + j55 ohms
SWR 1.37
Mismatch Loss 0.11 dB
Wire Loss 0.04 dB
Mismatched Gain 9.39 dBd
F/B 41.41 dB
98.000 MHz: Impedance 237 + j42 ohms
SWR 1.33
Mismatch Loss 0.09 dB
Wire Loss 0.03 dB
Mismatched Gain 9.66 dBd
F/B 47.70 dB
100.000 MHz: Impedance 231 + j35 ohms
SWR 1.34
Mismatch Loss 0.09 dB
Wire Loss 0.03 dB
Mismatched Gain 9.93 dBd
F/B 37.43 dB
102.000 MHz: Impedance 214 + j44 ohms
SWR 1.46
Mismatch Loss 0.16 dB
Wire Loss 0.04 dB
Mismatched Gain 10.14 dBd
F/B 36.11 dB
104.000 MHz: Impedance 213 + j85 ohms
SWR 1.61
Mismatch Loss 0.24 dB
Wire Loss 0.04 dB
Mismatched Gain 10.24 dBd
F/B 39.37 dB
106.000 MHz: Impedance 263 + j85 ohms
SWR 1.39
Mismatch Loss 0.12 dB
Wire Loss 0.06 dB
Mismatched Gain 10.24 dBd
F/B 32.27 dB
108.000 MHz: Impedance 116 + j112 ohms
SWR 3.00
Mismatch Loss 1.25 dB
Wire Loss 0.13 dB
Mismatched Gain 8.19 dBd
F/B 29.80 dB
Performance
Calculated
Average gain: 9.33 dBd (balun loss not included) Average F/B: 35.45 dBSpecified
Average gain: 10 dBd (balun included with antenna; loss not specified) Average F/B: 30 dBKen Wetzel measured the loss of an APS balun as approximately 0.75 dB. Subtract this amount from the calculated gain figures if you use a 75-ohm feedline.
Patterns
Antenna File
APS-13 Free Space 98.000 MHz 71 6063-T832 wires, inches e = 98.4375-89.1875 ; element spacing 9.25 f = 89.1875-77.5625 ; element spacing 11.625 g = 77.5625-66.0625 ; element spacing 11.5 s2 = .71875 / 2 ; phasing-line half-spacing at crossover point (first) s1 = .375 / 2 ; phasing-line half-spacing at crossover point (others) d = .11 ; phasing-line diameter r = 1.875 / 2 ; spacing of rivets on insulated elements x1 = 3.375 ; x at first phasing-line kink x2 = 3.875 ; x at second kink x3 = e - x2 ; x at third kink x4 = e - x1 ; x at fourth kink x5 = f - x2 ; x at third kink x6 = f - x1 ; x at fourth kink x7 = g - x2 ; x at third kink x8 = g - x1 ; x at fourth kink e2 = e / 2 ; half of element spacing y1 = r * (1 - x1 / e2) ; y at first kink y2 = r * (1 - x2 / e2) ; y at second kink f2 = f / 2 ; half of element spacing y5 = r * (1 - x1 / f2) ; y at first kink y6 = r * (1 - x2 / f2) ; y at second kink g2 = g / 2 ; half of element spacing y7 = r * (1 - x1 / g2) ; y at first kink y8 = r * (1 - x2 / g2) ; y at second kink 1 -42.8125 -r 0.0000 -42.8125 r 0.0000 0.3750 1 -98.4375 -r 0.0000 -98.4375 r 0.0000 0.3771 1 -98.4375 -32.9109 0.0000 -98.4375 -r 0.0000 0.3771 1 -98.4375 r 0.0000 -98.4375 32.9109 0.0000 0.3771 1 -89.1875 -29.5625 0.0000 -89.1875 -r 0.0000 0.3750 1 -89.1875 r 0.0000 -89.1875 29.5625 0.0000 0.3750 1 -77.5625 -28.4375 0.0000 -77.5625 -r 0.0000 0.3750 1 -77.5625 r 0.0000 -77.5625 28.4375 0.0000 0.3750 1 -66.0625 -26.1875 0.0000 -66.0625 -r 0.0000 0.3750 1 -66.0625 r 0.0000 -66.0625 26.1875 0.0000 0.3750 1 -54.4375 -24.9375 0.0000 -54.4375 -r 0.0000 0.3750 1 -54.4375 r 0.0000 -54.4375 24.9375 0.0000 0.3750 1 -46.6875 -25.5074 -1.8750 -46.6875 25.5074 -1.8750 0.3792 1 -42.8125 -16.9375 0.0000 -42.8125 -r 0.0000 0.3750 1 -42.8125 r 0.0000 -42.8125 16.9375 0.0000 0.3750 1 -29.1875 -25.1307 0.0000 -29.1875 25.1307 0.0000 0.3794 1 -8.5625 -24.5026 0.0000 -8.5625 24.5026 0.0000 0.3797 1 14.4375 -24.5026 0.0000 14.4375 24.5026 0.0000 0.3797 1 40.4375 -24.0001 0.0000 40.4375 24.0001 0.0000 0.3799 1 67.4375 -23.4975 0.0000 67.4375 23.4975 0.0000 0.3802 1 98.4375 -21.9892 0.0000 98.4375 21.9892 0.0000 0.3812 shift x -98.4375 1 0 r 0 x1 y1 0 d 1 x1 y1 0 x2 y2 -s2 d 1 x2 y2 -s2 x3 -y2 -s2 d 1 x3 -y2 -s2 x4 -y1 0 d 1 x4 -y1 0 e -r 0 d 1 0 -r 0 x1 -y1 0 d 1 x1 -y1 0 x2 -y2 s2 d 1 x2 -y2 s2 x3 y2 s2 d 1 x3 y2 s2 x4 y1 0 d 1 x4 y1 0 e r 0 d shift x -89.1875 1 0 r 0 x1 y5 0 d 1 x1 y5 0 x2 y6 -s1 d 1 x2 y6 -s1 x5 -y6 -s1 d 1 x5 -y6 -s1 x6 -y5 0 d 1 x6 -y5 0 f -r 0 d 1 0 -r 0 x1 -y5 0 d 1 x1 -y5 0 x2 -y6 s1 d 1 x2 -y6 s1 x5 y6 s1 d 1 x5 y6 s1 x6 y5 0 d 1 x6 y5 0 f r 0 d shift x -77.5625 1 0 r 0 x1 y7 0 d 1 x1 y7 0 x2 y8 -s1 d 1 x2 y8 -s1 x7 -y8 -s1 d 1 x7 -y8 -s1 x8 -y7 0 d 1 x8 -y7 0 g -r 0 d 1 0 -r 0 x1 -y7 0 d 1 x1 -y7 0 x2 -y8 s1 d 1 x2 -y8 s1 x7 y8 s1 d 1 x7 y8 s1 x8 y7 0 d 1 x8 y7 0 g r 0 d shift x -66.0625 1 0 r 0 x1 y5 0 d 1 x1 y5 0 x2 y6 -s1 d 1 x2 y6 -s1 x5 -y6 -s1 d 1 x5 -y6 -s1 x6 -y5 0 d 1 x6 -y5 0 f -r 0 d 1 0 -r 0 x1 -y5 0 d 1 x1 -y5 0 x2 -y6 s1 d 1 x2 -y6 s1 x5 y6 s1 d 1 x5 y6 s1 x6 y5 0 d 1 x6 y5 0 f r 0 d shift x -54.4375 1 0 r 0 x1 y5 0 d 1 x1 y5 0 x2 y6 -s1 d 1 x2 y6 -s1 x5 -y6 -s1 d 1 x5 -y6 -s1 x6 -y5 0 d 1 x6 -y5 0 f -r 0 d 1 0 -r 0 x1 -y5 0 d 1 x1 -y5 0 x2 -y6 s1 d 1 x2 -y6 s1 x5 y6 s1 d 1 x5 y6 s1 x6 y5 0 d 1 x6 y5 0 f r 0 d 1 source Wire 1, center Disable bent-wire correction and use 80 segments/halfwave.I used the YO 7.65 Yagi Optimizer program to calculate the effect of the mounting brackets on the uninsulated elements. The equivalent elements are shorter and thicker than the actual elements. Feedpoint detail was not modeled.
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Updated July 8, 2007
