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 60 analysis segments per conductor halfwave. Forward gain includes mismatch and conductor losses and correction by pattern integration. 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      204+j136    1.93     0.46      0.12      8.55      20.27
    89      170+j85     1.97     0.49      0.08      8.62      23.74
    90      161+j99     2.13     0.61      0.07      8.55      25.57
    91      174+j114    2.07     0.56      0.06      8.64      26.78
    92      195+j120    1.91     0.45      0.05      8.82      28.05
    93      217+j117    1.74     0.33      0.05      9.00      29.60
    94      234+j107    1.60     0.24      0.04      9.17      30.79
    95      246+j96     1.50     0.17      0.04      9.32      31.90
    96      252+j85     1.42     0.13      0.04      9.47      33.02
    97      257+j74     1.36     0.10      0.03      9.61      34.37
    98      259+j64     1.32     0.08      0.03      9.76      35.70
    99      257+j54     1.28     0.07      0.03      9.91      36.81
   100      249+j44     1.28     0.07      0.03     10.04      33.45
   101      235+j40     1.33     0.09      0.03     10.14      31.57
   102      217+j47     1.45     0.15      0.04     10.20      30.42
   103      203+j65     1.60     0.24      0.04     10.20      29.77
   104      199+j93     1.74     0.33      0.04     10.15      29.50
   105      212+j119    1.78     0.36      0.05     10.09      29.41
   106      232+j121    1.68     0.29      0.06     10.02      29.32
   107      204+j101    1.74     0.33      0.07      9.64      29.74
   108      127+j156    3.10     1.32      0.12      8.05      31.10

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".

July 7, 201888108 MHz