70-Element Yagi

I designed this 1296-MHz Yagi with the YO 8.0 Yagi Optimizer. It has 70 elements and is 32 wavelengths long (24′-3″). The red curve is element-current magnitude.

I calibrated the model to NEC-2 using 30 segments/halfwave. I optimized forward gain, F/R, and SWR. The optimizer calculated about 3500 Yagis per second on a 3-GHz Intel Core 2 using 2 pattern resolution..

Parasitic elements are made of ⅛″ 6061-T6 aluminum rod. The elements can be heated, fused into small blocks of polystyrene, and mounted above the boom. The driven element uses a folded dipole made of #10 copper wire. Mount it with the conductors one above the other equidistant from the antenna centerline. The folded dipole provides a good match for 50Ω coax with the wires spaced ⅜″ center-to-center. To adjust the match, vary the spacing to alter the effective driven element diameter and feedpoint reactance. Use a current balun.

Yagi File

70-Element Yagi
1292 1296 1300 MHz
70 elements, inches
          .1018971  .125
0         0         2.218646
2.741739  2.078064  0
3.747157  0         2.025863
6.551195  0         1.925237
9.791524  0         1.87467
13.38389  0         1.837225
17.20673  0         1.806169
21.06219  0         1.78786
25.05212  0         1.765842
29.17011  0         1.74509
33.24411  0         1.72962
37.65327  0         1.717246
41.70296  0         1.71461
46.00951  0         1.690279
50.35718  0         1.682516
54.66454  0         1.676326
59.00826  0         1.655208
63.53801  0         1.666083
67.73363  0         1.674114
72.00345  0         1.652175
76.43732  0         1.643049
80.91463  0         1.632862
85.3515   0         1.650392
89.51016  0         1.651082
93.88485  0         1.623264
98.55251  0         1.616135
102.7758  0         1.615814
107.4364  0         1.617414
111.7277  0         1.63179
115.9565  0         1.624446
120.4985  0         1.600838
125.0127  0         1.602668
129.3902  0         1.608261
133.7315  0         1.601455
138.348   0         1.597448
142.8746  0         1.613331
146.9849  0         1.623314
151.4198  0         1.597819
155.9436  0         1.579314
160.477   0         1.572316
164.962   0         1.611736
169.2138  0         1.592489
173.7355  0         1.594579
178.0754  0         1.595766
182.574   0         1.580067
187.0966  0         1.569788
191.4924  0         1.56017
195.924   0         1.601282
200.4704  0         1.556082
204.8442  0         1.575314
209.3402  0         1.563859
213.8145  0         1.564465
218.1914  0         1.589824
222.7912  0         1.584353
227.0731  0         1.580498
231.5845  0         1.596391
235.9845  0         1.593101
240.1536  0         1.588526
244.8952  0         1.606565
249.0344  0         1.608304
253.4002  0         1.590297
257.91    0         1.578736
262.288   0         1.58791
266.7422  0         1.578912
271.147   0         1.623286
275.3071  0         1.611352
279.821   0         1.605461
284.0814  0         1.609529
288.095   0         1.674421
291.4908  0         1.738877
Match: 4 .1018971 .375 2.078064 0 0 50 0 0
Cal: 22.72233 160.7003 .02892013 .9995333 .9793859 .9519646 1.486928 -18.04852

February 19, 201888108 MHz