MY TWINBOOM YAGI ANTENNAS FOR 144 MHZ
You have a small house yard and there is no room for a bigger antenna? Probably, the twinboom antenna is the answer. The characteristics of a 10 metres long yagi antenna can be achieved with a 6.5 to 7 metres long twinboom antenna .
This is a little bit unusual approach to making high gain antennas. The point is to build two vertically stacked yagi antennas, which stacking distance is small.. The reflector, the radiator (and sometimes the first director) are common for both yagis.
The small distance stacking gives not so great gain increase. It is usually around 1 dB over a single yagi (maximum 1.5 dB), but there are other benefits of such configuration.
As seen, the booms should be slightly bent toward each other for best performance. The vertical distance after bending is not critical, so a little error in bending is negligible. However, the horizontal distance between elements should be kept very precise, as given in the tables for every particular antenna. This means, the element distance/position is given on the centerline between the booms and should be converted onto vertical projections on both booms precisely.
Every antenna model has double quad radiator. I have designed many twinboom antennas with open, folded or LFA radiator, but found the double quad the best shape of radiator. The antenna with such a radiator gives up to 0.5 dB additional gain in comparison to other radiator forms.
One can say this configuration is hard for building. No, it is not! Both booms strengthen each other, and both booms are additionally reinforced by mounting on a vertical frame holder. At the ends, both booms are finally squeezed to maintain the necessary boom bending, which gives some more strength. You can, even, use a very small diameter boom.
I built a 8 meter long double boom yagi for 50 MHz using Ø25 mm Aluminum tubes, 1 mm thick. This antenna was standing on the tower for three years with no problems with strongest winds at all. Note, the Ø25 mm tube, 1 mm thick, 6 meter long, is just 1 kilo of Aluminum. This antenna gain was nearly 14 dBi. For such gain level, a classic style yagi should be 11 to 12 meters long - which means much thicker boom tube, plus boom reinforcements.
Here you can see the photo which speaks more than words. I built them with LFA radiators. Later on I got awared that double quad performs better. so now I am preparing to replace LFA radiators with double quad ones. This antenna is for 144 MHz, 5.625 meters long. Booms are 25/1 mm diameter, soft Aluminum!
If you want the same performance with classic style yagis, you have to choose a yagi 8 to 9 meters long. Imagine how strong its boom should be.
Further bellow you can see my EME system consisted of four such antennas. I started working with them in October 2016 and established many nice EME QSOs till now. Several severe storms blew with no consequences at all. Although, I can compare them to my previous antennas 16 x 9 ele hybrids, which were blown in June 2016 by a tornado (who sais there have never been tornados in my area???).
For me they are performing very satisfying. The only lack is – XPOL is not possible with this antenna type.
Down in the Table you can find the list of my best twinboom antennas. You can compare them to YU7EF antennas and see all benefits they offer. For example, 6 elements YU7EF yagi gives the G/T worse for 2.4 dB! than X21205XL4QQ. With longer booms, the difference becomes lower. In my opinion, twinboom antennas extremely pay off within 3 WL of boom length, though one can estimate reasonable to build even longer tweens. Look at the Table and think.
Have a nice time building and DXing.
Note: KF2YN correction is applied on all models. The formula should be applied because the antenna modelling software (NEC/EZNEC) does not contain the KF2YN formula and cannot fight off the convergence error caused by tappered or sharply bent elements. After applying, antenna data are standardized and can be put into VE7BQH table alongside with other competing antennas. Therefore, do not be confused with different results of gain in tables and in diagrams! The correction gives the real gain for ALUMINUM. Except for gain, the differences in other parameters (F/B, F/S etc) are minor and can be neglected.
|
Antenna X21705XL1 under the test |
|
The same antennas stacked vertically at 5.00 meters and horizontally at 4.40 meters |
DOUBLE BOOM ANTENNAS FOR 144 MHz – YU7XL
(INSERTED DATA FOR YU7EF ANTENNAS FOR COMPARISON)
|
ANTENNA TYPE |
No of ele |
Ǿ (mm) |
Length (mm) |
Type |
Gain (dB) |
F/B (dB) |
F/Sh (dB) |
F/Sv (dB) |
H lobe (◦) |
V lobe (◦) |
TA (◦K)* |
G/T (dB)* |
Tloss (dB) |
Δf (SWR=1.5) |
|
|
Lower |
Upper |
||||||||||||||
| X21005XL8Q | 10 | 5 | 1645 | Q | 12.37 | 26.84 | - | 17.33 | 48.8 | 44.6 | 254.0 | -11.68 | 4.2 | 140.700 | 146.400 |
| X21006XL3Q | 10 | 6 | 1645 | Q | 12.42 | 24.80 | - | 17.38 | 48.6 | 44.6 | 252.8 | -11.60 | 3.6 | 141.400 | 146.700 |
| X21008XL3Q | 10 | 8 | 1645 | Q | 12.57 | 23.17 | - | 15.82 | 48.2 | 42.5 | 250.6 | -11.42 | 3.0 | 141.300 | 146.300 |
| X21010XL6Q | 10 | 10 | 1645 | Q | 12.66 | 23.18 | - | 15.51 | 48.2 | 41.4 | 249.8 | -11.32 | 2.7 | 141.600 | 146.500 |
|
12 |
5 |
2305 |
Q |
13.44 |
34.34 |
- |
16.14 |
44.5 |
38.1 |
235.8 |
-10.29 |
4.5 |
141.800 |
146.800 |
|
|
12 |
6 |
2305 |
Q |
13.46 |
32.68 |
- |
16.82 |
44.5 |
37.9 |
233.8 |
-10.22 |
3.9 |
142.200 |
146.400 |
|
|
12 |
8 |
2305 |
Q |
13.50 |
40.36 |
- |
16.96 |
44.5 |
37.7 |
233.1 |
-10.18 |
3.3 |
141.200 |
146.400 |
|
|
12 |
10 |
2305 |
Q |
13.54 |
26.94 |
- |
17.33 |
44.6 |
37.0 |
230.8 |
-10.09 |
2.7 |
141.400 |
146.600 |
|
|
EF0206-5 |
6 |
5 |
2377 |
Classic 50Ώ |
11,82 |
26.99 |
25.06 |
14,50 |
46,2 |
55,4 |
282.6 |
-12,69 |
5.2 |
140,200 |
145,300 |
| X21405XL5Q | 14 | 5 | 2945 | Q | 14.16 | 34.87 | - | 16.16 | 41.8 | 34.4 | 225.8 | 9.38 | 5.1 | 140.000 | 146.700 |
| X21406XL4Q | 14 | 6 | 2945 | Q | 14.16 | 38.35 | - | 16.30 | 41.8 | 34.4 | 225.1 | 9.36 | 4.8 | 140.000 | 146.600 |
| X21408XL4Q | 14 | 8 | 2945 | Q | 14.20 | 34.09 | - | 16.59 | 41.8 | 34.2 | 224.5 | 9.32 | 3.6 | 139.400 | 147.100 |
| X21410XL9Q | 14 | 10 | 2945 | Q | 14.23 | 32.27 | - | 16.87 | 41.8 | 33.8 | 224.4 | 9.28 | 3.0 | 139.200 | 147.300 |
|
16 |
5 |
3605 |
Q |
14.88 |
26.76 |
- |
16.86 |
38.2 |
30.8 |
228.9 |
-8.71 |
6.0 |
141.600 |
147.200 |
|
|
16 |
6 |
3605 |
Q |
14.90 |
26.96 |
- |
17.20 |
38.4 |
30.3 |
227.5 |
-8.67 |
5.4 |
141.200 |
146.800 |
|
|
16 |
8 |
3605 |
Q |
14.94 |
28.67 |
25.37 |
16.48 |
38.7 |
29.8 |
225.6 |
-8.60 |
4.5 |
141.000 |
146.600 |
|
|
16 |
10 |
3605 |
Q |
14.96 |
26.85 |
26.45 |
15.95 |
38.6 |
30.6 |
225.3 |
-8.57 |
3.3 |
141.000 |
146.700 |
|
|
EF0207-5 |
7 |
5 |
3274 |
Classic 50Ώ |
12,83 |
26.54 |
25.33 |
17,35 |
42,6 |
49.0 |
255,6 |
-11,25 |
6.1 |
140,400 |
145,100 |
|
EF0208-5 |
8 |
5 |
3900 |
Classic 50Ώ |
13,42 |
22,43 |
22,12 |
15,37 |
40,2 |
45,2 |
248,9 |
-10,54 |
5.2 |
141,220 |
145,490 |
|
18 |
5 |
4365 |
Q |
15.48 |
27.69 |
24.23 |
16.69 |
36.2 |
28.7 |
224.4 |
-8.03 |
6.0 |
141.800 |
147.600 |
|
|
18 |
6 |
4365 |
Q |
15.44 |
29.42 |
25.36 |
16.37 |
36.6 |
29.6 |
222.6 |
-8.04 |
4.5 |
142.100 |
148.400 |
|
|
18 |
8 |
4365 |
Q |
15.51 |
29.31 |
24.60 |
16.40 |
36.4 |
29.2 |
222.9 |
-7.97 |
3.9 |
141.500 |
147.700 |
|
|
18 |
10 |
4365 |
Q |
15.54 |
25.94 |
22.78 |
17.32 |
36.2 |
28.2 |
223.3 |
-7.95 |
3.6 |
141.000 |
146.300 |
|
|
EF0209-5 |
9 |
5 |
4490 |
Classic 50Ώ |
13.97 |
22.69 |
22,63 |
16,67 |
38.0 |
42,4 |
240.3 |
-9.84 |
4.9 |
140,100 |
145,480 |
|
20 |
5 |
5165 |
Q |
15.85 |
33.94 |
23.14 |
19.14 |
34.0 |
28.8 |
217.7 |
-7.53 |
5.4 |
141.400 |
146.300 |
|
|
20 |
6 |
5165 |
Q |
15.90 |
27.11 |
21.83 |
19.76 |
33.6 |
28.0 |
219.2 |
-7.51 |
5.1 |
142.000 |
146.200 |
|
|
20 |
8 |
5205 |
Q |
15.92 |
34.43 |
23.86 |
18.27 |
33.8 |
28.8 |
218.6 |
-7.48 |
3.0 |
140.600 |
146.900 |
|
|
20 |
10 |
5205 |
Q |
15.97 |
32.96 |
22.79 |
19.06 |
33.4 |
28.2 |
218.4 |
-7.42 |
2.7 |
140.300 |
146.500 |
|
|
EF0210-5 |
10 |
5 |
5290 |
Classic 50Ώ |
14,64 |
21.81 |
21.98 |
17,33 |
35.0 |
38,4 |
234.4 |
-9.05 |
7.0 |
143.000 |
144.900 |
|
EF0211B-5 |
11 |
5 |
5980 |
Classic 50Ώ |
15,01 |
29,44 |
21,13 |
17,11 |
33,8 |
36,8 |
230.1 |
-8,61 |
6.7 |
140,600 |
145,210 |
|
22 |
5 |
5985 |
Q |
16.38 |
38.61 |
23.00 |
18.02 |
31.8 |
26.4 |
219.9 |
-7.04 |
6.3 |
141.800 |
146.600 |
|
|
22 |
6 |
5985 |
Q |
16.39 |
30.83 |
20.96 |
18.80 |
31.5 |
26.0 |
219.6 |
-7.03 |
5.7 |
142.200 |
146.400 |
|
|
22 |
8 |
5985 |
Q |
16.44 |
31.24 |
17.25 |
18.98 |
31.8 |
26.6 |
217.9 |
-6.94 |
3.9 |
141.600 |
147.600 |
|
|
22 |
10 |
5985 |
Q |
16.44 |
30.36 |
- |
18.89 |
31.6 |
26.2 |
218.1 |
-6.95 |
3.3 |
142.200 |
146.800 |
|
|
EF0211-5 |
11 |
5 |
6325 |
Classic 50Ώ |
15,12 |
22.29 |
22.38 |
18,30 |
33,8 |
36,8 |
225.5 |
-8,41 |
.7.0 |
142,500 |
144,750 |
| X22405XL2Q | 24 | 5 | 6725 | Q | 16.78 | 31.70 | 29.44 | 18.05 | 30.6 | 26.2 | 219.9 | -6.64 | 6.3 | 140.400 | 146.500 |
| X22406XL2Q | 24 | 6 | 6725 | Q | 16.80 | 31.17 | 27.97 | 19.02 | 30.6 | 24.8 | 220.1 | -6.63 | 6.0 | 141.000 | 146.300 |
|
24 |
8 |
6725 |
Q |
16.81 |
31.51 |
29.44 |
18.11 |
30.4 |
25.6 |
218.8 |
-6.59 |
3.9 |
140.600 |
147.700 |
|
|
24 |
10 |
6725 |
Q |
16.83 |
33.09 |
28.13 |
18.70 |
30.2 |
25.0 |
219.0 |
-6.57 |
3.6 |
140.200 |
147.200 |
|
|
EF0212-5 |
12 |
5 |
7260 |
Classic 50Ώ |
15,78 |
22.38 |
20,22 |
16,79 |
31,4 |
33,6 |
224,4 |
-7.73 |
6.7 |
143,300 |
144,820 |
|
26 |
5 |
7505 |
Q |
17.10 |
29.08 |
15.98 |
16.59 |
29.4 |
25.0 |
221.1 |
-6.34 |
5.1 |
141.400 |
148.600 |
|
|
26 |
6 |
7505 |
Q |
17.17 |
27.23 |
15.08 |
17.21 |
29.0 |
24.4 |
220.5 |
-6.26 |
4.8 |
141.000 |
148.000 |
|
|
26 |
8 |
7505 |
Q |
17.15 |
28.26 |
15.39 |
18.18 |
28.8 |
24.0 |
218.8 |
-6.25 |
4.5 |
140.600 |
146.600 |
|
|
26 |
10 |
7505 |
Q |
17.20 |
28.92 |
14.95 |
18.00 |
28.8 |
24.2 |
219.1 |
-6.21 |
3.3 |
140.000 |
146.400 |
|
|
EF0213M-5 |
13 |
5 |
7940 |
Classic 50Ώ |
15.98 |
26.51 |
22.08 |
19.08 |
30.8 |
32.8 |
225.3 |
-7.55 |
8.1 |
140.500 |
146.000 |
|
EF0213-5 |
13 |
5 |
8150 |
Classic 50Ώ |
16,19 |
23.95 |
20.22 |
17.3 |
30.0 |
31,8 |
222.5 |
-7.28 |
8.1 |
143,660 |
144,620 |
|
28 |
5 |
8285 |
Q |
17.44 |
30.58 |
15.58 |
16.26 |
28.0 |
24.0 |
221.7 |
-6.01 |
5.1 |
141.600 |
148.300 |
|
|
28 |
6 |
8285 |
Q |
17.50 |
26.23 |
14.98 |
16.57 |
27.6 |
23.4 |
221.2 |
-5.95 |
5.1 |
142.000 |
147.700 |
|
|
28 |
8 |
8285 |
Q |
17.49 |
27.26 |
16.82 |
17.31 |
28.2 |
24.0 |
218.6 |
-5.91 |
3.9 |
142.000 |
147.000 |
|
|
28 |
10 |
8285 |
Q |
17.53 |
26.62 |
16.12 |
18.02 |
27.8 |
23.4 |
218.5 |
-5.86 |
3.6 |
142.000 |
146.200 |
|
|
30 |
5 |
9065 |
Q |
17.73 |
39.42 |
16.03 |
15.58 |
27.0 |
23.2 |
221.7 |
-5.73 |
5.1 |
140.800 |
148.000 |
|
|
30 |
6 |
9065 |
Q |
17.80 |
32.22 |
15.39 |
15.97 |
26.6 |
22.6 |
220.3 |
-5.62 |
5.1 |
141.600 |
147.400 |
|
|
30 |
8 |
9065 |
Q |
17.81 |
33.94 |
16.36 |
17.05 |
26.8 |
22.6 |
217.2 |
-5.56 |
4.2 |
141.800 |
146.500 |
|
|
30 |
10 |
9065 |
Q |
17.82 |
36.92 |
16.48 |
17.58 |
26.8 |
22.6 |
217.3 |
-5.55 |
3.6 |
141.200 |
146.300 |
|
|
EF0214-5 |
14 |
5 |
9100 |
Classic 50Ώ |
16,64 |
22,72 |
20,34 |
17,69 |
28,4 |
30,2 |
222,7 |
-6.84 |
9.3 |
143,720 |
144,620 |
|
30 |
5 |
9845 |
Q |
18.03 |
42.07 |
15.56 |
15.51 |
26.0 |
22.2 |
221.3 |
-5.42 |
5.4 |
141.000 |
148.100 |
|
|
30 |
6 |
9845 |
Q |
18.08 |
35.81 |
14.93 |
15.58 |
25.6 |
21.6 |
219.8 |
-5.34 |
5.4 |
141.000 |
147.400 |
|
|
30 |
8 |
9845 |
Q |
18.09 |
34.88 |
15.10 |
16.12 |
25.6 |
21.5 |
217.9 |
-5.29 |
4.8 |
141.000 |
146.700 |
|
|
30 |
10 |
9845 |
Q |
18.10 |
41.67 |
16.39 |
17.00 |
25.8 |
21.7 |
216.5 |
-5.25 |
4.5 |
140.800 |
146.500 |
|
|
EF0215-5 |
15 |
5 |
10060 |
Classic 50Ώ |
17,05 |
24.96 |
19.42 |
17.01 |
26,8 |
28.2 |
220.7 |
-6,39 |
10.2 |
143,750 |
144,460 |