I used the AO 9.65 Antenna Optimizer to design this Yagi for DAB/DAB+ reception on Band III (174–240 MHz). The antenna has two reflectors, nine elements total, and a boom length of 1.3 m. The red dot is the 50Ω feedpoint.
I optimized the design for maximum forward gain without regard for the pattern. 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 174 44.9-j15.9 1.42 0.13 0.01 6.41 9.08 177 60.0-j10.4 1.30 0.08 0.01 6.62 11.57 180 73.3-j10.9 1.53 0.19 0.01 6.56 12.73 183 82.0-j14.6 1.72 0.32 0.01 6.47 12.67 186 85.8-j18.6 1.83 0.39 0.01 6.42 12.18 189 86.9-j20.8 1.88 0.43 0.01 6.42 11.70 192 86.1-j20.9 1.87 0.42 0.01 6.49 11.32 195 85.2-j19.2 1.83 0.39 0.01 6.61 11.07 198 84.7-j16.4 1.79 0.36 0.01 6.75 10.93 201 85.1-j13.0 1.76 0.34 0.01 6.91 10.84 204 86.7-j10.1 1.77 0.35 0.01 7.08 10.83 207 88.5-j8.5 1.79 0.37 0.01 7.25 10.91 210 89.7-j9.0 1.82 0.38 0.01 7.44 11.10 213 88.2-j11.9 1.81 0.38 0.01 7.67 11.30 216 82.1-j14.5 1.72 0.32 0.01 7.95 11.55 219 71.2-j13.2 1.52 0.19 0.01 8.30 11.90 222 59.4-j5.0 1.21 0.04 0.02 8.65 12.10 225 51.6+j9.7 1.21 0.04 0.02 8.84 12.47 228 51.9+j28.4 1.74 0.33 0.03 8.71 13.08 231 71.4+j44.3 2.23 0.68 0.03 8.42 14.16 234 94.3+j4.5 1.89 0.43 0.05 8.51 13.95 237 38.8+j3.2 1.30 0.07 0.08 8.45 12.65 240 50.9+j0.7 1.02 0.00 0.17 8.00 12.03
DAB Yagi Free Space 174 185 195 205 215 225 230 234 238 240 MHz 9 6063-T832 wires, mm r = 413.46056 ; element half-lengths de = 378.15444 d1 = 299.392 d2 = 292.918 d3 = 282.92443 d4 = 270.88173 d5 = 274.0881 d6 = 273.67305 rp = 0 ; element positions dep = 260.5823 d1p = 293.695 d2p = 389.2611 d3p = 598.53183 d4p = 834.04703 d5p = 1043.5107 d6p = 1300 s = 290.96865 ; reflector half-spacing 1 rp s -r rp s r 10 1 rp -s -r rp -s r 10 1 dep 0 -de dep 0 de 10 1 d1p 0 -d1 d1p 0 d1 10 1 d2p 0 -d2 d2p 0 d2 10 1 d3p 0 -d3 d3p 0 d3 10 1 d4p 0 -d4 d4p 0 d4 10 1 d5p 0 -d5 d5p 0 d5 10 1 d6p 0 -d6 d6p 0 d6 10 1 source Wire 3, center
Use 10 mm aluminum tubing supported by insulated mounts. Symbols r, de, and d1-d6 are element half-lengths (center to tip), rp, dep, and d1p-d6p are element positions, and s is the reflector half-spacing. Rear-mount the antenna with the mast 100 mm behind the reflector plane. Route the 50Ω coax to the rear and down the mast. Install at least one ferrite choke at the feedpoint.
The following table shows the largest performance degradation over the antenna file frequencies in dB when altering a single dimension by Tol.
Symbol Tol Gain F/R
r 0.5000 0.01 0.15
de 0.5000 0.02 0.01
d1 0.5000 0.10 0.08
d2 0.5000 0.12 0.43
d3 0.5000 0.10 0.22
d4 0.5000 0.03 0.05
d5 0.5000 0.05 0.20
d6 0.5000 0.04 0.11
rp 1.0000 0.00 0.01
dep 1.0000 0.06 0.05
d1p 1.0000 0.07 0.08
d2p 1.0000 0.03 0.07
d3p 1.0000 0.02 0.02
d4p 1.0000 0.01 0.03
d5p 1.0000 0.01 0.05
d6p 1.0000 0.01 0.04
s 1.0000 0.00 0.02
This array has 22 elements. Boom length is 2.55 m, stacking distance is 0.92 m, and the reflectors span 1.25 m. The reflectors have unequal but symmetrical lengths and offsets.
I used AO 9.63 to optimize both forward gain and the pattern, including suppression of secondary forward lobes. Calculated performance is for 28 analysis segments per conductor halfwave. Forward gain includes mismatch and conductor losses, but not stacking cable or power combiner 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 174 47.3-j16.4 1.40 0.12 0.01 9.41 20.00 177 56.5-j10.4 1.26 0.06 0.01 9.60 25.31 180 65.6-j6.5 1.34 0.09 0.01 9.67 24.68 183 74.4-j4.4 1.50 0.18 0.01 9.70 24.12 186 81.6-j4.4 1.64 0.26 0.01 9.73 23.58 189 86.8-j5.7 1.75 0.33 0.01 9.79 22.44 192 89.9-j7.4 1.81 0.38 0.01 9.88 21.68 195 90.9-j8.6 1.84 0.40 0.01 10.01 21.18 198 91.0-j8.9 1.84 0.40 0.01 10.17 20.98 201 90.1-j8.1 1.82 0.39 0.01 10.37 21.02 204 89.3-j6.6 1.80 0.37 0.01 10.59 21.03 207 88.5-j4.9 1.78 0.35 0.01 10.82 20.68 210 87.3-j3.7 1.75 0.34 0.01 11.07 20.46 213 85.6-j2.8 1.72 0.31 0.01 11.35 20.07 216 81.8-j1.2 1.64 0.26 0.01 11.67 19.82 219 76.8+j2.3 1.54 0.20 0.01 12.01 19.91 222 73.1+j8.1 1.50 0.17 0.02 12.32 19.98 225 73.2+j14.3 1.56 0.22 0.02 12.57 20.01 228 75.8+j14.0 1.60 0.24 0.03 12.81 20.60 231 65.9+j6.3 1.35 0.10 0.04 13.14 22.56 234 48.6+j18.3 1.45 0.15 0.06 13.12 20.50 237 63.2+j25.1 1.65 0.27 0.09 12.81 20.29 240 47.4+j4.3 1.11 0.01 0.26 12.54 19.97
Stacked DAB Yagis Free Space Symmetrix 174 190 205 214 220 227 235 238 239 240 MHz 11 6063-T832 wires, mm ri = 450.4879 ; element half-lengths ro = 429.8947 de = 387.8235 d1 = 301.6371 d2 = 295.2137 d3 = 284.4728 d4 = 278.1006 d5 = 270.8748 d6 = 269.2393 d7 = 265.1729 d8 = 257.9645 dep = 259.0257 ; element positions d1p = 289.2319 d2p = 362.3309 d3p = 566.4574 d4p = 879.4938 d5p = 1271.861 d6p = 1678.719 d7p = 2147.34 d8p = 2548.055 o = 163.84 ; outer reflector offset i = 278.1921 ; inner reflector offset sp = 461.1318 ; boom half-spacing shift y sp 1 0 -i -ri 0 -i ri 10 1 0 o -ro 0 o ro 10 1 dep 0 -de dep 0 de 10 1 d1p 0 -d1 d1p 0 d1 10 1 d2p 0 -d2 d2p 0 d2 10 1 d3p 0 -d3 d3p 0 d3 10 1 d4p 0 -d4 d4p 0 d4 10 1 d5p 0 -d5 d5p 0 d5 10 1 d6p 0 -d6 d6p 0 d6 10 1 d7p 0 -d7 d7p 0 d7 10 1 d8p 0 -d8 d8p 0 d8 10 1 source Wire 3, center
Use 10 mm aluminum tubing supported by insulated mounts. Rear-mount the antenna if possible. Otherwise use a nonconductive mast section in the vicinity of the antenna. Use at least one ferrite choke at each feedpoint and connect 50Ω cables of equal length to a 50Ω hybrid power combiner. For lower loss, replace the hybrid with two 75Ω cables, each an electrical quarter-wavelength long at 204 MHz (305 mm for Belden 1530A) joined with a junction splitter. SWR for this combiner will be 1.25 maximum and total loss 0.1 dB maximum over 174–240 MHz. Use 50Ω coax from the end of the 75Ω cables to the antenna feedpoints and from combiner to the receiver.
To increase forward gain 3 dB, stack two of the 22-element arrays vertically with their booms 2.5 meters apart.
The following table shows the largest performance degradation over the antenna file frequencies in dB when altering a single dimension by Tol.
Symbol Tol Gain F/R
ri 0.5000 0.00 0.08
ro 0.5000 0.00 0.18
de 0.5000 0.01 0.01
d1 0.5000 0.10 0.08
d2 0.5000 0.17 0.89
d3 0.5000 0.10 0.45
d4 0.5000 0.08 1.27
d5 0.5000 0.07 0.44
d6 0.5000 0.07 0.69
d7 0.5000 0.02 0.28
d8 0.5000 0.01 0.18
dep 1.0000 0.06 0.10
d1p 1.0000 0.07 0.12
d2p 1.0000 0.03 0.16
d3p 1.0000 0.01 0.12
d4p 1.0000 0.01 0.11
d5p 1.0000 0.01 0.07
d6p 1.0000 0.01 0.12
d7p 1.0000 0.01 0.07
d8p 1.0000 0.00 0.11
o 1.0000 0.00 0.02
i 1.0000 0.00 0.01
sp 1.0000 0.00 0.08
Petr Vozár erected this 22-element stack at Přerov, Czech Republic. It rotates here.
88–108 MHz