Antenna Performance Specialties APS-13

The Antenna Performance Specialties APS-13 is a log-Yagi array with 13 elements on a 197″ boom. Five of the elements are driven. A shorted phasing line terminates at a passive reflector.

I modeled the antenna with the AO 9.67 Antenna Optimizer. This image shows the antenna geometry.

This shows phasing line and feedpoint detail. I added a wire across the feedpoint terminals and placed a source at its center. Blue dots mark analysis segments. The red dot is the feedpoint.

Modeling Results

Calculated performance is for 28 analysis segments per conductor halfwave with automatic segment-length tapering ratio set to 1.2. Forward gain includes mismatch and conductor losses. F/R is the ratio of forward power to that of the worst backlobe in the rear half-plane.

Frequency  Impedance    SWR   Mismatch  Conductor   Forward     F/R 
   MHz        ohms             Loss dB   Loss dB   Gain dBd      dB 
    88     219 + j146   1.90     0.44      0.13      8.39      19.90
    89     177 + j85    1.89     0.43      0.08      8.57      23.71
    90     165 + j98    2.09     0.58      0.07      8.50      25.74
    91     176 + j114   2.05     0.55      0.06      8.59      27.03
    92     195 + j122   1.92     0.46      0.05      8.74      28.08
    93     217 + j120   1.76     0.34      0.05      8.92      29.62
    94     234 + j111   1.62     0.25      0.04      9.09      30.87
    95     246 + j100   1.52     0.19      0.04      9.25      31.97
    96     253 + j90    1.44     0.15      0.04      9.39      33.20
    97     258 + j80    1.38     0.11      0.04      9.54      34.50
    98     261 + j71    1.34     0.09      0.03      9.69      35.84
    99     261 + j61    1.29     0.07      0.03      9.84      36.57
   100     256 + j51    1.28     0.06      0.03      9.98      33.26
   101     242 + j45    1.31     0.08      0.03     10.10      31.55
   102     225 + j49    1.41     0.13      0.04     10.18      30.32
   103     211 + j66    1.55     0.20      0.04     10.21      29.87
   104     206 + j92    1.69     0.29      0.04     10.18      29.76
   105     214 + j120   1.77     0.35      0.05     10.13      29.54
   106     240 + j130   1.70     0.30      0.06     10.09      29.86
   107     234 + j108   1.61     0.24      0.07      9.90      29.82
   108     161 + j131   2.32     0.75      0.10      8.90      30.60

Antenna File

APS-13
Free Space
98.000 MHz
89 6063-T832 wires, inches
rp = 0			; element positions
e1p = 9.25
e2p = 20.875
e3p = 32.5
e4p = 44.125
e5p = 55.75
d1p = 51.75
d2p = 69.375
d3p = 90
d4p = 113
d5p = 138.75
d6p = 165.75
d7p = 196.75
eqd = 1.28		; element + mounting plate equivalent diameter
d = .11			; phasing-line diameter
r = 1.875 / 2		; spacing of rivets on insulated elements
b = .75			; feedpoint bolt length
x1 = 3			; x at first phasing-line bend
e = e1p - rp		; phasing line length   (R-DE1)
s2 = .5 / 2		; phasing-line half-spacing at crossover point
x2 = 3.125		; x at second bend
x3 = e - x2		; x at third bend
x4 = e - x1		; x at fourth bend
e2 = e / 2		; half of element spacing
y1 = r * (1 - x1 / e2)	; y at first bend
y2 = r * (1 - x2 / e2)	; y at second bend
f = e2p - e1p		; phasing line length   (DE1-DE2 ... DE4-DE5)
s1 = .375 / 2		; phasing-line half-spacing at crossover point
w2 = 3.4375		; x at second bend
x5 = f - w2		; x at third bend
x6 = f - x1		; x at fourth bend
f2 = f / 2		; half of element spacing
y5 = r * (1 - x1 / f2)	; y at first bend
y6 = r * (1 - w2 / f2)	; y at second bend
1    rp   -33.25     0    rp   -2         0    0.375
1    rp   -2         0    rp   -1.25      0     eqd
3    rp   -1.25      0    rp    1.25      0     eqd
1    rp    1.25      0    rp    2         0     eqd
1    rp    2         0    rp    33.25     0    0.375
1    e1p  -29.75     0    e1p  -r         0    0.375
1    e1p   r         0    e1p   29.75     0    0.375
1    e2p  -28.625    0    e2p  -r         0    0.375
1    e2p   r         0    e2p   28.625    0    0.375
1    e3p  -26.25     0    e3p  -r         0    0.375
1    e3p   r         0    e3p   26.25     0    0.375
1    e4p  -25.125    0    e4p  -r         0    0.375
1    e4p   r         0    e4p   25.125    0    0.375
1    d1p  -26.125   -2    d1p   -2       -2    0.375
1    d1p   -2       -2    d1p    2       -2     eqd
1    d1p    2       -2    d1p   26.125   -2    0.375
1    e5p  -17        0    e5p  -r         0    0.375
1    e5p  -r         0    e5p  -r        -b    0.125    zinc
4    e5p  -r        -b    e5p   r        -b      #16    copper
1    e5p   r         0    e5p   r        -b    0.125	zinc
1    e5p   r         0    e5p   17        0    0.375
1    d2p  -25.625    0    d2p   -2        0    0.375
1    d2p   -2        0    d2p    2        0     eqd
1    d2p    2        0    d2p   25.625    0    0.375
1    d3p  -25.125    0    d3p   -2        0    0.375
1    d3p   -2        0    d3p    2        0     eqd
1    d3p    2        0    d3p   25.125    0    0.375
1    d4p  -25        0    d4p   -2        0    0.375
1    d4p   -2        0    d4p    2        0     eqd
1    d4p    2        0    d4p   25        0    0.375
1    d5p  -24.625    0    d5p   -2        0    0.375
1    d5p   -2        0    d5p    2        0     eqd
1    d5p    2        0    d5p   24.625    0    0.375
1    d6p  -24        0    d6p   -2        0    0.375
1    d6p   -2        0    d6p    2        0     eqd
1    d6p    2        0    d6p   24        0    0.375
1    d7p  -22.5      0    d7p   -2        0    0.375
1    d7p   -2        0    d7p    2        0     eqd
1    d7p    2        0    d7p   22.5      0    0.375
2   0   1.25  0     x1   y1   0    d
1   x1   y1   0     x2   y2  -s2   d
6   x2   y2  -s2    x3  -y2  -s2   d
1   x3  -y2  -s2    x4  -y1   0    d
2   x4  -y1   0     e   -r    0    d
2   0  -1.25  0     x1  -y1   0    d
1   x1  -y1   0     x2  -y2   s2   d
6   x2  -y2   s2    x3   y2   s2   d
1   x3   y2   s2    x4   y1   0    d
2   x4   y1   0     e     r   0    d
shift x e1p
3   0     r   0     x1   y5   0    d
1   x1   y5   0     w2   y6  -s1   d
8   w2   y6  -s1    x5  -y6  -s1   d
1   x5  -y6  -s1    x6  -y5   0    d
3   x6  -y5   0     f    -r   0    d
3   0    -r   0     x1  -y5   0    d
1   x1  -y5   0     w2  -y6   s1   d
8   w2  -y6   s1    x5   y6   s1   d
1   x5   y6   s1    x6   y5   0    d
3   x6   y5   0     f     r   0    d
shift x e2p
3   0     r   0     x1   y5   0    d
1   x1   y5   0     w2   y6  -s1   d
8   w2   y6  -s1    x5  -y6  -s1   d
1   x5  -y6  -s1    x6  -y5   0    d
3   x6  -y5   0     f    -r   0    d
3   0    -r   0     x1  -y5   0    d
1   x1  -y5   0     w2  -y6   s1   d
8   w2  -y6   s1    x5   y6   s1   d
1   x5   y6   s1    x6   y5   0    d
3   x6   y5   0     f     r   0    d
shift x e3p
3   0     r   0     x1   y5   0    d
1   x1   y5   0     w2   y6  -s1   d
8   w2   y6  -s1    x5  -y6  -s1   d
1   x5  -y6  -s1    x6  -y5   0    d
3   x6  -y5   0     f    -r   0    d
3   0    -r   0     x1  -y5   0    d
1   x1  -y5   0     w2  -y6   s1   d
8   w2  -y6   s1    x5   y6   s1   d
1   x5   y6   s1    x6   y5   0    d
3   x6   y5   0     f     r   0    d
shift x e4p
3   0     r   0     x1   y5   0    d
1   x1   y5   0     w2   y6  -s1   d
8   w2   y6  -s1    x5  -y6  -s1   d
1   x5  -y6  -s1    x6  -y5   0    d
3   x6  -y5   0     f    -r   0    d
3   0    -r   0     x1  -y5   0    d
1   x1  -y5   0     w2  -y6   s1   d
8   w2  -y6   s1    x5   y6   s1   d
1   x5   y6   s1    x6   y5   0    d
3   x6   y5   0     f     r   0    d
1 source
Wire 19, center

I modeled the 4" x 1.625" x 0.5" x 0.05" element mounting brackets as
U-channels with the YO 8.00 Yagi Optimizer. YO calculated the equivalent
cylindrical diameter as 1.28".
Set automatic segment-length tapering ratio to 1.2.

June 23, 201888108 MHz