These five Yagis with booms two to six meters long use metric dimensions. Each design maximizes forward gain while keeping all backlobes at least 30 dB down over 87.5–108 MHz. The Yagis use a driven element loop that couples to the first director in a way that greatly improves the pattern. I optimized all designs with the AO 9.65 Antenna Optimizer.
This antenna has eight elements on a two-meter boom. The red dot is the 75Ω feedpoint, which has a small series capacitor.
Calculated performance is for 28 analysis segments per conductor halfwave. 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
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
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 (one side of center) 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
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
This antenna has ten elements on a three-meter boom.
Calculated performance is for 28 analysis segments per conductor halfwave. 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
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
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 (one side of center) 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
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
This antenna has 12 elements on a four-meter boom.
Calculated performance is for 28 analysis segments per conductor halfwave. 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
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
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 (one side of center) 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
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
This antenna has 15 elements on a five-meter boom.
Calculated performance is for 28 analysis segments per conductor halfwave. 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
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
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 (one side of center) 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
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
This antenna has 17 elements on a six-meter boom.
Calculated performance is for 28 analysis segments per conductor halfwave. 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
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
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 (one side of center) 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
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
Measure all dimensions to the 10 mm tubing centerline. The loop must be in the element plane in front of the driven element. Support everything with hydraulic tubing clamps. Connect the 75Ω coax center conductor through the specified capacitance to one tube at the feedpoint gap. Connect the shield to the other tube. Make the connections as close as possible to the gap, which should be 2 to 6 mm long. Keep all leads as short as possible. Waterproof the capacitor and connections. Use a 5% ceramic capacitor with the highest voltage rating readily available to minimize the chance of failure due to a nearby lightning strike. Use a current choke at the feedpoint.
Paul Ormandy, ZL4TT, built this loop. For proper coupling to the adjacent director, the connections should be closer to the tubing ends at the feedpoint gap. Nevertheless, Paul reports that the antenna works very well.
Larry Horlick, VO1FOG, built this loop. The short capacitor leads minimize stray inductance.
Dave Kibler, NR8TV, built this neat copper loop with covered feedpoint. Copper/aluminum junctions should be weatherproofed to avoid corrosion due to dissimilar electrode potential that can cause high contact resistance.
It may be easier to construct the driven element and loop with 15 mm × 3 mm flat bars interconnected by 10 mm round tubes with a long bolt or threaded rod inside. The bars are electrically equivalent to 10 mm round tubes.
You can use 6063-T5 aluminum angle from Home Depot. The 0.5″ × 0.5″ right-angle shape is electrically equivalent to a 0.4″ round conductor, which is very close 10 mm. For accurate conductor spacing, mount all elements with the angle oriented the same way. For symmetry, mount the loop sides with the horizontal part toward the boom. The electrical centerline is 0.125″ in from the vertical part.
Check the antenna with a vector network analyzer. Do not alter element lengths or spacings to improve SWR. If you weatherproof it, you can substitute a small air trimmer for the fixed capacitor.
Dave Kibler erected this six-meter Yagi above a barn in Greenfield, Ohio. He uses a Kitz mast-mount preamp.
Paul Ormandy erected this three-meter Yagi in Oamaru, New Zealand.
Bryan Clark uses this three-meter Yagi in Mangawhai, Northland, New Zealand. The lower Yagi is too close.
Larry Horlick built this three-meter Yagi in Coley's Point South, Newfoundland, Canada.
Larry received these signals over a 24-hour period in July, 2022.
Performance Comparison
Gallery
December 23, 2022
88–108 MHz