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Gain 11,0 dBd, F/B 25 dBd Boom 3,30 m Stacking distance 2,80 m 3dB-angles: 39,4° hor, 44,4° ver |
| Details | 2-El.-2m | 3-El.-2m | 4-El.-2m | 5-El.-2m | 6-El.-2m |
| 7-El.-2m | 7-El.-70cm | 9-El.-70cm | 10-El.-70cm | 12-El.-70cm | 14-El.-70cm |
| Stacked 5-El-2m 25-Ohm new | 7-El.-2m 25+28-Ohm new | 8-El.-2m 28-Ohm new | 10-El.-70cm 28-Ohm new |
Version 1: The 7-Element-28Ohm-Leightweight-Yagi for 2m
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Gain 11,0 dBd, F/B 25 dBd Boom 3,30 m Stacking distance 2,80 m 3dB-angles: 39,4° hor, 44,4° ver |
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It is possible to build the well known 7-El.-28-Ohm-Yagi with an aluminium-boom 20x1,5mm. The coax socket ist grounded to the boom with a screw and an aluminium angle. |
|
Elements |
Ref |
Rad
(8mm) |
Dir
1 |
Dir
2 |
Dir
3 |
Dir
4 |
Dir
5 |
|
Position |
0mm |
320mm |
595mm |
1145mm |
1825mm |
2615mm |
3260mm |
|
L
(3,2mm) |
1016mm |
976mm |
964mm |
943mm |
925mm |
928mm |
913mm |
|
L
(4mm) |
1014mm |
976mm |
961mm |
938mm |
920mm |
923mm |
908mm |
Version 2: The 7-Element-25-Ohm-Leightweight-Yagi for stacking
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Boom 3,40 m Broadband Gain 11,05 dBd, F/B 26 dB 3-dB-Angles: hor 39,6° ver 44,6°
Stacking distance 2,80 m |
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With two Yagis of 25-Ohm- impedance an easy stacking
is possible. We need two pieces of 5/4-λ-coax-cable
with 50 Ω.
The 25 Ω
at XX are transformed to 100 Ω at XX.
I use Aircell-5 with 2x2,04 m.
With both cables L1 and L2 parallel we get the 50 Ω for the cable to the TRX. The first 45 cm of the 204 cm long pieces are wound to a coax-choke for surpressing common mode currents. The two chokes are in the radiator-box, we do not need coax sockets and connectors. The picture on the right side down shows the measuring of the stacking cable with 2x 50-Ω- resistors (0,5%) parallel for 25 Ω impedance.
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| The left picture shows the choke,here are 45 cm of the coax wound
on a 25-mm-PVC-tube. The right picture shows the 2x50-Ohm resistors
(1/2%) parallel. With both chokes and two resistors of 25 Ohm, length of
2x2,04 m Aircell-5 the SWR is 1,0. Between 144,0 and 144,5 MHz the
impedance is 50 +/- j 0 Ohm.
On 143 MHz R= 49 - j 5 Ohm, on 146 MHz R= 51 + j 5 Ohm, the impedance with an analyzer is shown down: |
The two connected radiators with 2x 2,04 m Aircell stacked
Lengths and positions of the elements, radiator always 4mm
|
Element |
Position |
8 mm |
6
mm |
4
mm |
3,2
mm |
|
Reflector |
0
mm |
1020 mm |
1022
mm |
1024
mm |
1027
mm |
|
Radiator |
300
mm |
974 mm (8 mm) |
982
mm (6 mm) |
984
mm |
986
mm (4 mm) |
|
Director
1 |
645
mm |
937 mm |
946
mm |
953
mm |
954
mm |
|
Director
2 |
1245
mm |
914 mm |
924
mm |
930
mm |
937
mm |
|
Director
3 |
1945
mm |
896 mm |
908
mm |
918
mm |
922
mm |
|
Director
4 |
2750
mm |
894 mm |
904
mm |
916
mm |
920
mm |
|
Director
5 |
3380
mm |
892 mm |
903
mm |
913
mm |
917
mm |
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