Metric Yagis

These five Yagis use metric dimensions and booms two to six meters long. Each design maximizes forward gain while keeping all backlobes at least 30 dB down over 87.5108 MHz. The Yagis feature a loop-coupled driven element that couples to the first director in a way that greatly improves the pattern. It yields higher forward gain than a horizontal folded dipole and does not require a 75:300Ω balun. It does need a series capacitance at the feedpoint. I optimized all designs with the AO 9.65 Antenna Optimizer.

Two-Meter Yagi

This antenna has eight elements on a two-meter boom. The red dot is the 75Ω feedpoint.

Modeling Results

Calculated performance is for 28 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 
     87.5   67.3 + j6.6   1.15     0.02      0.02      5.83      30.01  
    88    69.7 + j3.0   1.09     0.01      0.02      5.85      33.02
    89    71.6 - j2.3   1.06     0.00      0.02      5.89      31.98
    90    71.8 - j4.7   1.08     0.01      0.02      5.93      30.98
    91    72.1 - j5.3   1.09     0.01      0.02      5.99      30.30
    92    73.0 - j4.6   1.07     0.00      0.02      6.06      30.01
    93    74.4 - j3.9   1.05     0.00      0.02      6.14      29.94
    94    76.7 - j3.2   1.05     0.00      0.02      6.24      30.08
    95    79.4 - j3.2   1.07     0.01      0.02      6.33      30.37
    96    82.3 - j4.0   1.11     0.01      0.02      6.43      30.33
    97    85.1 - j6.0   1.16     0.02      0.02      6.53      30.22
    98    87.3 - j9.1   1.21     0.04      0.02      6.63      30.14
    99    88.4 - j13.3  1.26     0.06      0.02      6.73      30.04
   100    88.1 - j18.6  1.32     0.08      0.02      6.83      30.01
   101    85.6 - j24.4  1.39     0.12      0.02      6.92      30.04
   102    80.0 - j30.0  1.48     0.16      0.02      6.99      30.06
   103    72.0 - j33.8  1.58     0.23      0.03      7.04      30.24
   104    62.1 - j34.6  1.71     0.31      0.03      7.05      30.73
   105    52.1 - j30.8  1.83     0.39      0.04      7.03      30.52
   106    45.4 - j22.1  1.86     0.41      0.05      7.02      30.01
   107    49.0 - j9.2   1.57     0.22      0.07      7.13      30.00
   108    95.8 - j30.7  1.54     0.20      0.14      6.80      30.00

Antenna File

Two-Meter Yagi
Free Space Symmetric
87.5 90 92 95 98 100 102 104 105 106 107 108 MHz
13 6063-T832 wires, meters
h = .33148386		; reflector height
rp = 0			; element positions
dep = .32403963
d1p = .5089447
d2p = .6648566
d3p = 1.0631633
d4p = 1.3091594
d5p = 2
r = .8995709		; element half-lengths
de = .7865902
d1 = .6754952
d2 = .66206912
d3 = .6179316
d4 = .59579233
d5 = .5510639
w = .062135155		; loop half-width
s = .14489323		; loop side
p = dep + s
1     rp  -r  h     rp   r  h    .01
1     rp  -r -h     rp   r -h    .01
1    dep   w  0    dep  de  0    .01
1    dep  -w  0    dep -de  0    .01
6    dep  -w  0    dep   w  0    .01
6      p  -w  0      p   w  0    .01
7      p   w  0    dep   w  0    .01
7      p  -w  0    dep  -w  0    .01
1    d1p -d1  0    d1p  d1  0    .01
1    d2p -d2  0    d2p  d2  0    .01
1    d3p -d3  0    d3p  d3  0    .01
1    d4p -d4  0    d4p  d4  0    .01
1    d5p -d5  0    d5p  d5  0    .01
1 source
Wire 6, center
1 load
c = 8.85914		; series feedpoint capacitor
Wire 6, center c pF

Sensitivity Analysis

The following table shows the largest performance degradation over 87.5, 93, 98, 103, and 108 MHz in dB when altering a symbol value by Tol.

Symbol      Tol   Gain    F/R
     h   0.0010   0.00   0.13
    rp   0.0010   0.00   0.10
   dep   0.0010   0.02   0.20
   d1p   0.0010   0.05   0.17
   d2p   0.0010   0.03   0.14
   d3p   0.0010   0.00   0.13
   d4p   0.0010   0.00   0.08
   d5p   0.0010   0.00   0.07
     r   0.0005   0.00   0.26
    de   0.0005   0.00   0.07
    d1   0.0005   0.05   0.66
    d2   0.0005   0.15   1.10
    d3   0.0005   0.01   0.28
    d4   0.0005   0.00   0.21
    d5   0.0005   0.00   0.12
     w   0.0005   0.01   0.00
     s   0.0010   0.01   0.11
     c   0.8859   0.31   0.00

Three-Meter Yagi

This antenna has ten elements on a three-meter boom. The red dot is the 75Ω feedpoint.

Modeling Results

Calculated performance is for 28 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 
     87.5   71.9 + j5.8   1.12     0.01      0.02      7.08      30.00  
    88    75.4 + j2.1   1.03     0.00      0.02      7.12      30.33
    89    78.3 - j4.5   1.08     0.01      0.02      7.19      30.89
    90    77.5 - j8.2   1.12     0.01      0.02      7.27      31.29
    91    75.6 - j9.0   1.13     0.02      0.02      7.37      31.70
    92    74.0 - j7.4   1.11     0.01      0.02      7.48      31.30
    93    73.2 - j4.2   1.06     0.00      0.02      7.61      30.65
    94    73.6 - j0.0   1.02     0.00      0.02      7.74      30.21
    95    75.7 + j4.2   1.06     0.00      0.02      7.87      30.00
    96    79.2 + j8.2   1.13     0.02      0.02      7.99      30.03
    97    84.2 + j11.1  1.20     0.04      0.02      8.12      30.34
    98    90.1 + j12.2  1.27     0.06      0.02      8.24      30.74
    99    96.0 + j10.2  1.32     0.08      0.02      8.36      31.47
   100     100 + j6     1.35     0.10      0.02      8.49      32.15
   101     101 - j0     1.35     0.10      0.02      8.62      31.51
   102    98.4 - j5.4   1.32     0.08      0.03      8.74      30.75
   103    94.6 - j7.1   1.28     0.07      0.03      8.84      30.19
   104    92.3 - j6.2   1.25     0.05      0.03      8.89      30.00
   105    93.8 - j7.5   1.27     0.06      0.04      8.85      30.00
   106    92.8 - j15.9  1.33     0.09      0.05      8.69      30.15
   107    79.3 - j18.0  1.27     0.06      0.06      8.42      30.48
   108    77.2 + j7.7   1.11     0.01      0.09      7.98      30.00

Antenna File

Three-Meter Yagi
Free Space Symmetric
87.5 90 92 95 97 102 104 105 106 107 108 MHz
15 6063-T832 wires, meters
h = .5936546		; outer reflector height
rp = 0			; element positions
dep = .43079176
d1p = .64241151
d2p = .923438
d3p = 1.3318776
d4p = 1.670833
d5p = 2.2196736
d6p = 3
ro = .9211657		; outer reflector half-length
ri = .92941854		; inner reflector half-length
de = .7777548		; driven element half-length
d1 = .6591962		; director half-lengths
d2 = .6485328
d3 = .631916
d4 = .62899653
d5 = .6248731
d6 = .56236
w = .063599702		; loop half-width
s = .17045478		; loop side
p = dep + s
1     rp -ro  h     rp  ro  h    .01
1     rp -ri  0     rp  ri  0    .01
1     rp -ro -h     rp  ro -h    .01
1    dep   w  0    dep  de  0    .01
1    dep  -w  0    dep -de  0    .01
6    dep  -w  0    dep   w  0    .01
6      p  -w  0      p   w  0    .01
7      p   w  0    dep   w  0    .01
7      p  -w  0    dep  -w  0    .01
1    d1p -d1  0    d1p  d1  0    .01
1    d2p -d2  0    d2p  d2  0    .01
1    d3p -d3  0    d3p  d3  0    .01
1    d4p -d4  0    d4p  d4  0    .01
1    d5p -d5  0    d5p  d5  0    .01
1    d6p -d6  0    d6p  d6  0    .01
1 source
Wire 7, center
1 load
c = 7.646869		; series feedpoint capacitor
Wire 7, center c pF

Sensitivity Analysis

The following table shows the largest performance degradation over 87.5, 93, 98, 103, and 108 MHz in dB when altering a symbol value by Tol.

Symbol      Tol   Gain    F/R
     h   0.0010   0.00   0.05
    rp   0.0010   0.00   0.03
   dep   0.0010   0.01   0.17
   d1p   0.0010   0.01   0.23
   d2p   0.0010   0.00   0.21
   d3p   0.0010   0.00   0.23
   d4p   0.0010   0.00   0.21
   d5p   0.0010   0.00   0.23
   d6p   0.0010   0.00   0.06
    ro   0.0005   0.00   0.10
    ri   0.0005   0.00   0.06
    de   0.0005   0.00   0.06
    d1   0.0005   0.01   0.04
    d2   0.0005   0.03   0.38
    d3   0.0005   0.01   0.45
    d4   0.0005   0.02   0.48
    d5   0.0005   0.01   0.16
    d6   0.0005   0.00   0.04
     w   0.0005   0.01   0.00
     s   0.0010   0.01   0.09
     c   0.7647   0.16   0.00

Four-Meter Yagi

This antenna has 12 elements on a four-meter boom. The red dot is the 75Ω feedpoint.

Modeling Results

Calculated performance is for 28 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 
     87.5   66.1 + j2.0   1.14     0.02      0.02      7.73      30.01  
    88    67.8 - j1.0   1.11     0.01      0.02      7.78      32.40
    89    68.4 - j5.0   1.12     0.01      0.02      7.88      31.46
    90    67.3 - j6.4   1.15     0.02      0.02      7.99      30.72
    91    66.1 - j5.5   1.16     0.02      0.02      8.11      30.24
    92    65.4 - j3.3   1.16     0.02      0.02      8.25      30.04
    93    65.3 - j0.1   1.15     0.02      0.02      8.40      30.05
    94    66.1 + j3.4   1.14     0.02      0.02      8.56      30.16
    95    67.9 + j6.8   1.15     0.02      0.02      8.72      30.44
    96    70.5 + j10.1  1.16     0.02      0.02      8.89      30.01
    97    74.0 + j12.6  1.18     0.03      0.02      9.06      29.85
    98    78.3 + j13.9  1.20     0.04      0.02      9.22      30.01
    99    83.1 + j13.3  1.22     0.04      0.02      9.39      30.79
   100    86.8 + j9.9   1.21     0.04      0.02      9.54      31.76
   101    88.4 + j3.5   1.19     0.03      0.03      9.68      31.66
   102    84.7 - j2.8   1.14     0.02      0.03      9.80      31.31
   103    76.6 - j5.3   1.08     0.01      0.03      9.86      30.87
   104    69.0 - j2.5   1.10     0.01      0.04      9.84      30.56
   105    65.8 + j4.1   1.15     0.02      0.05      9.71      30.14
   106    69.3 + j8.5   1.15     0.02      0.06      9.45      30.01
   107    72.1 + j7.4   1.11     0.01      0.07      9.01      30.04
   108    85.2 + j15.8  1.27     0.06      0.11      8.37      30.00

Antenna File

Four-Meter Yagi
Free Space Symmetric
87.5 90 92 96 98 102 104 105 106 107.3 108 MHz
17 6063-T832 wires, meters
h = .662275		; outer reflector height
rp = 0			; element positions
dep = .42542764
d1p = .6497597
d2p = .92435173
d3p = 1.3558378
d4p = 1.6891916
d5p = 2.210484
d6p = 2.7830176
d7p = 3.297144
d8p = 4
ro = .9587851		; outer reflector half-length
ri = .8920225		; inner reflector half-length
de = .78423271		; driven element half-length
d1 = .66296		; director half-lengths
d2 = .65120224
d3 = .6303252
d4 = .6268042
d5 = .633065
d6 = .6152197
d7 = .5906129
d8 = .5427582
w = .057672142		; loop half-width
s = .18430494		; loop side
p = dep + s
1     rp -ro  h     rp  ro  h    .01
1     rp -ri  0     rp  ri  0    .01
1     rp -ro -h     rp  ro -h    .01
1    dep   w  0    dep  de  0    .01
1    dep  -w  0    dep -de  0    .01
6    dep  -w  0    dep   w  0    .01
6      p  -w  0      p   w  0    .01
7      p   w  0    dep   w  0    .01
7      p  -w  0    dep  -w  0    .01
1    d1p -d1  0    d1p  d1  0    .01
1    d2p -d2  0    d2p  d2  0    .01
1    d3p -d3  0    d3p  d3  0    .01
1    d4p -d4  0    d4p  d4  0    .01
1    d5p -d5  0    d5p  d5  0    .01
1    d6p -d6  0    d6p  d6  0    .01
1    d7p -d7  0    d7p  d7  0    .01
1    d8p -d8  0    d8p  d8  0    .01
1 source
Wire 7, center
1 load
c = 7.874907		; series feedpoint capacitor
Wire 7, center c pF

Sensitivity Analysis

The following table shows the largest performance degradation over 87.5, 93, 98, 103, and 108 MHz in dB when altering a symbol value by Tol.

Symbol      Tol   Gain    F/R
     h   0.0010   0.00   0.06
    rp   0.0010   0.00   0.05
   dep   0.0010   0.01   0.08
   d1p   0.0010   0.01   0.16
   d2p   0.0010   0.00   0.13
   d3p   0.0010   0.01   0.07
   d4p   0.0010   0.00   0.05
   d5p   0.0010   0.01   0.11
   d6p   0.0010   0.00   0.10
   d7p   0.0010   0.00   0.05
   d8p   0.0010   0.00   0.02
    ro   0.0005   0.00   0.04
    ri   0.0005   0.00   0.16
    de   0.0005   0.00   0.03
    d1   0.0005   0.02   0.07
    d2   0.0005   0.02   0.53
    d3   0.0005   0.01   0.16
    d4   0.0005   0.02   0.15
    d5   0.0005   0.04   0.27
    d6   0.0005   0.00   0.13
    d7   0.0005   0.00   0.13
    d8   0.0005   0.00   0.08
     w   0.0005   0.01   0.00
     s   0.0010   0.01   0.05
     c   0.7875   0.16   0.00

Five-Meter Yagi

This antenna has 15 elements on a five-meter boom. The red dot is the 75Ω feedpoint.

Modeling Results

Calculated performance is for 28 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 
     87.5   77.7 + j7.9   1.11     0.01      0.02      8.61      30.01  
    88    81.2 + j3.9   1.10     0.01      0.02      8.68      30.22
    89    83.9 - j3.2   1.13     0.02      0.02      8.82      30.60
    90    82.8 - j7.4   1.15     0.02      0.02      8.96      30.98
    91    80.8 - j8.4   1.14     0.02      0.02      9.12      31.46
    92    79.2 - j7.1   1.11     0.01      0.02      9.29      30.82
    93    79.0 - j4.3   1.08     0.01      0.02      9.47      30.33
    94    79.8 - j1.4   1.07     0.00      0.02      9.64      30.11
    95    82.1 + j1.2   1.10     0.01      0.02      9.82      30.00
    96    85.4 + j2.6   1.14     0.02      0.02      9.98      30.10
    97    88.8 + j2.3   1.19     0.03      0.02     10.14      30.36
    98    91.4 + j0.3   1.22     0.04      0.02     10.29      30.89
    99    92.5 - j3.1   1.24     0.05      0.02     10.43      31.39
   100    91.6 - j6.8   1.24     0.05      0.03     10.55      31.92
   101    89.1 - j10.8  1.24     0.05      0.03     10.64      30.70
   102    84.2 - j13.8  1.23     0.05      0.03     10.67      30.00
   103    76.3 - j15.3  1.22     0.04      0.04     10.63      30.11
   104    67.5 - j12.2  1.22     0.04      0.04     10.50      30.35
   105    62.7 - j4.2   1.21     0.04      0.05     10.27      30.10
   106    66.5 + j3.3   1.14     0.02      0.07      9.95      30.11
   107    74.2 - j0.1   1.01     0.00      0.09      9.59      30.15
   108    92.0 - j5.4   1.24     0.05      0.13      9.31      30.00

Antenna File

Five-Meter Yagi
Free Space Symmetric
87.5 90 92 95 98 100 101 102 104 105 106 107.3 108 MHz
20 6063-T832 wires, meters
h = .64018831		; outer reflector height
rp = 0			; element positions
dep = .49362727
d1p = .7323495
d2p = .9825406
d3p = 1.3258083
d4p = 1.5986318
d5p = 1.88034
d6p = 2.3715476
d7p = 2.901946
d8p = 3.339485
d9p = 3.8708207
d10p = 4.292037
d11p = 5
ro = .9131784		; outer reflector half-length
ri = .9172915		; inner reflector half-length
de = .777831		; driven element half-length
d1 = .6636809		; director half-lengths
d2 = .6560028
d3 = .6412648
d4 = .6248576
d5 = .625728
d6 = .6240153
d7 = .59576843
d8 = .6129011
d9 = .6009722
d10 = .60116664
d11 = .5691937
w = .064433102		; loop half-width
s = .17888163		; loop side
p = dep + s
1     rp -ro  h     rp  ro  h    .01
1     rp -ri  0     rp  ri  0    .01
1     rp -ro -h     rp  ro -h    .01
1    dep   w  0    dep  de  0    .01
1    dep  -w  0    dep -de  0    .01
6    dep  -w  0    dep   w  0    .01
6      p  -w  0      p   w  0    .01
8      p   w  0    dep   w  0    .01
8      p  -w  0    dep  -w  0    .01
1    d1p -d1  0    d1p  d1  0    .01
1    d2p -d2  0    d2p  d2  0    .01
1    d3p -d3  0    d3p  d3  0    .01
1    d4p -d4  0    d4p  d4  0    .01
1    d5p -d5  0    d5p  d5  0    .01
1    d6p -d6  0    d6p  d6  0    .01
1    d7p -d7  0    d7p  d7  0    .01
1    d8p -d8  0    d8p  d8  0    .01
1    d9p -d9  0    d9p  d9  0    .01
1   d10p -d10 0   d10p  d10 0    .01
1   d11p -d11 0   d11p  d11 0    .01
1 source
Wire 7, center
1 load
c = 7.467456		; series feedpoint capacitor
Wire 7, center c pF

Sensitivity Analysis

The following table shows the largest performance degradation over 87.5, 93, 98, 103, and 108 MHz in dB when altering a symbol value by Tol.

Symbol      Tol   Gain    F/R
     h   0.0010   0.00   0.06
    rp   0.0010   0.00   0.05
   dep   0.0010   0.01   0.11
   d1p   0.0010   0.01   0.11
   d2p   0.0010   0.00   0.08
   d3p   0.0010   0.00   0.06
   d4p   0.0010   0.00   0.08
   d5p   0.0010   0.00   0.07
   d6p   0.0010   0.00   0.14
   d7p   0.0010   0.00   0.10
   d8p   0.0010   0.00   0.04
   d9p   0.0010   0.00   0.08
  d10p   0.0010   0.00   0.14
  d11p   0.0010   0.00   0.10
    ro   0.0005   0.00   0.08
    ri   0.0005   0.00   0.08
    de   0.0005   0.00   0.04
    d1   0.0005   0.01   0.15
    d2   0.0005   0.03   0.39
    d3   0.0005   0.01   0.17
    d4   0.0005   0.01   0.05
    d5   0.0005   0.00   0.21
    d6   0.0005   0.01   0.12
    d7   0.0005   0.00   0.08
    d8   0.0005   0.01   0.26
    d9   0.0005   0.00   0.19
   d10   0.0005   0.00   0.06
   d11   0.0005   0.00   0.05
     w   0.0005   0.01   0.00
     s   0.0010   0.01   0.05
     c   0.7467   0.23   0.00

Six-Meter Yagi

This antenna has 17 elements on a six-meter boom. The red dot is the 75Ω feedpoint.

Modeling Results

Calculated performance is for 28 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 
     87.5   73.3 + j5.8   1.08     0.01      0.02      9.20      30.00  
    88    77.6 + j1.9   1.04     0.00      0.02      9.28      31.26
    89    81.5 - j6.2   1.12     0.01      0.02      9.43      30.65
    90    81.1 - j12.0  1.19     0.03      0.02      9.59      30.27
    91    78.5 - j14.9  1.22     0.04      0.02      9.76      30.03
    92    75.3 - j15.1  1.22     0.04      0.02      9.94      29.93
    93    72.9 - j12.9  1.19     0.03      0.02     10.15      30.01
    94    71.4 - j9.9   1.15     0.02      0.02     10.35      30.20
    95    71.6 - j6.1   1.10     0.01      0.02     10.55      30.21
    96    73.3 - j2.6   1.04     0.00      0.02     10.75      30.20
    97    76.2 - j0.5   1.02     0.00      0.02     10.92      30.45
    98    79.2 - j0.1   1.06     0.00      0.02     11.07      30.83
    99    80.9 - j1.5   1.08     0.01      0.03     11.18      31.31
   100    81.0 - j3.2   1.09     0.01      0.03     11.26      31.69
   101    80.5 - j4.8   1.10     0.01      0.03     11.28      32.37
   102    79.3 - j6.7   1.11     0.01      0.04     11.22      31.17
   103    76.8 - j10.8  1.15     0.02      0.05     11.06      30.26
   104    68.1 - j12.2  1.22     0.04      0.05     10.79      30.07
   105    61.0 - j4.5   1.24     0.05      0.07     10.47      30.19
   106    68.3 + j3.5   1.11     0.01      0.09     10.21      30.00
   107    71.7 - j7.9   1.12     0.01      0.11     10.13      29.93
   108    91.5 - j6.2   1.24     0.05      0.19     10.19      30.03

Antenna File

Six-Meter Yagi
Free Space Symmetric
87.5 93 95 98 100 101 102 103 104 105.3 106 107.3 108 MHz
22 6063-T832 wires, meters
h = .68362281		; outer reflector height
rp = 0			; element positions
dep = .49160462
d1p = .7263994
d2p = .9678485
d3p = 1.2847776
d4p = 1.5663208
d5p = 1.845225
d6p = 2.3067593
d7p = 2.7117047
d8p = 3.2256264
d9p = 3.7472078
d10p = 4.320997
d11p = 4.845762
d12p = 5.2749045
d13p = 6
ro = .9077651		; outer reflector half-length
ri = .9033324		; inner reflector half-length
de = .77851162		; driven element half-length
d1 = .66408083		; director half-lengths
d2 = .6608845
d3 = .65576074
d4 = .634097
d5 = .6372006
d6 = .6252573
d7 = .6117205
d8 = .6119818
d9 = .59872363
d10 = .61072752
d11 = .58825842
d12 = .6028955
d13 = .5670971
w = .062436035		; loop half-width
s = .1758659		; loop side
p = dep + s
1     rp -ro  h     rp  ro  h    .01
1     rp -ri  0     rp  ri  0    .01
1     rp -ro -h     rp  ro -h    .01
1    dep   w  0    dep  de  0    .01
1    dep  -w  0    dep -de  0    .01
6    dep  -w  0    dep   w  0    .01
6      p  -w  0      p   w  0    .01
8      p   w  0    dep   w  0    .01
8      p  -w  0    dep  -w  0    .01
1    d1p -d1  0    d1p  d1  0    .01
1    d2p -d2  0    d2p  d2  0    .01
1    d3p -d3  0    d3p  d3  0    .01
1    d4p -d4  0    d4p  d4  0    .01
1    d5p -d5  0    d5p  d5  0    .01
1    d6p -d6  0    d6p  d6  0    .01
1    d7p -d7  0    d7p  d7  0    .01
1    d8p -d8  0    d8p  d8  0    .01
1    d9p -d9  0    d9p  d9  0    .01
1   d10p -d10 0   d10p  d10 0    .01
1   d11p -d11 0   d11p  d11 0    .01
1   d12p -d12 0   d12p  d12 0    .01
1   d13p -d13 0   d13p  d13 0    .01
1 source
Wire 7, center
1 load
c = 7.631465		; series feedpoint capacitor
Wire 7, center c pF

Sensitivity Analysis

The following table shows the largest performance degradation over 87.5, 93, 98, 103, and 108 MHz in dB when altering a symbol value by Tol.

Symbol      Tol   Gain    F/R
     h   0.0010   0.00   0.04
    rp   0.0010   0.00   0.03
   dep   0.0010   0.01   0.11
   d1p   0.0010   0.01   0.10
   d2p   0.0010   0.00   0.11
   d3p   0.0010   0.01   0.07
   d4p   0.0010   0.00   0.10
   d5p   0.0010   0.00   0.03
   d6p   0.0010   0.00   0.11
   d7p   0.0010   0.00   0.09
   d8p   0.0010   0.00   0.04
   d9p   0.0010   0.00   0.07
  d10p   0.0010   0.00   0.13
  d11p   0.0010   0.00   0.10
  d12p   0.0010   0.00   0.04
  d13p   0.0010   0.00   0.03
    ro   0.0005   0.00   0.10
    ri   0.0005   0.00   0.08
    de   0.0005   0.00   0.00
    d1   0.0005   0.00   0.13
    d2   0.0005   0.04   0.23
    d3   0.0005   0.01   0.23
    d4   0.0005   0.00   0.03
    d5   0.0005   0.01   0.28
    d6   0.0005   0.01   0.21
    d7   0.0005   0.00   0.13
    d8   0.0005   0.01   0.24
    d9   0.0005   0.00   0.15
   d10   0.0005   0.01   0.08
   d11   0.0005   0.00   0.04
   d12   0.0005   0.01   0.25
   d13   0.0005   0.00   0.17
     w   0.0005   0.01   0.00
     s   0.0010   0.01   0.05
     c   0.7631   0.24   0.00

Construction

Tubing diameter is 10 mm. Flatten both ends of the tubes for the loop sides. Form each end into a circular clamp and drill holes for a screw. Measure loop dimensions to the tubing centerline. The loop must be in the element plane in front of the driven element. Connect the 75Ω coax shield to one side of the feedpoint gap. Connect the center conductor through the specified capacitance to the other side. Alternatively, use twice the capacitance in series with each coax lead. Keep the feedpoint gap and all leads as short as possible. Waterproof the connections. Use a current balun at the feedpoint.

Performance Comparison


April 23, 201788108 MHz