Details  2El.2m  3El.2m  4El.2m  5El.2m  6El.2m 
7El.2m  7El.70cm  9El.70cm  10El.70cm  12El.70cm  14El.70cm 
Stacked 5El2m 25Ohm new  7El.2m 25+28Ohm new  8El.2m 28Ohm  10El.70cm 28Ohm 
Two Versions of stacked 25OhmYagis (1,80 m and 2,00 m Boom)
The picture left shows shows the 4x5Element25OhmYagis with 2mboom and a stacking distance of 2,30 m. Two Yagis are connected together with Aircell5 transformations lines, the two groups are coupled with a powersplitter as described on the "stacking page". The Yagiarray handles 1 KW HF without any problems and was used for a test in the AlpeAdriaContest 2010. The array works excellent with a very good antenna pattern. The measured SWR of the complete group in the common feeding point is <=1,1 beween 144,0 and 144,8 MHz. At not very good band conditions QSOs from central Germany (450 m ASL) to middle Italy were possible, distance 800 1000 km. The Yagis on the picture are built with 8mmelements. The lowest antenna is 6 m above ground, with groundgain you can get 20 dBd gain! The Elevation angle is only 3°, the 3dBangle vertical is also only 2,8°. Plots below! 
Version 1: The stacked 5Element 25Ohm 2mYagi, Boom 180 cm Gain of each Yagi is 8,8 dBd, F/B 23 dB 3dBangles hor = 49,6°, ver = 61,6° Gain of the stacked array 11,5 dBd 3dBangles hor = 50,0°°, ver = 25,4° Stacking distance is 2,20 m

With two Yagis of 25Ohmimpedance an easy stacking
is possible. We need two pieces of 5/4λcoaxcable
with 50 Ω.
The 25 Ω
at XX are transformed to 100 Ω at XX.
With both cables L1 and L2 parallel we get the 50 Ω for the cable to the TRX. The first 45 cm of the 175,5 cm long pieces are wound to a coaxchoke for surpressing common mode currents. The two chokes are in the radiatorbox, we do not need coax sockets and connectors. 
The left picture shows the choke,here are 45 cm of the coax wound
on a 25mmPVCtube. The right picture shows the 2x50Ohm resistors
(1/2%) parallel. With both chokes and two resistors of 25 Ohm, length of
2x2,04 m Aircell5 the SWR is 1,0. Between 144,0 and 144,5 MHz the
impedance is 50 +/ j 0 Ohm.
First I started with a length of 213 cm (5/4lambda * V = 0,82). But this was to long (frequency to deep below 144 MHz). Then I cut the ends in the connection box until the resonance is exactly as you see in the picture of the analyzer. It may be that the individual coax cables differ from the calculated length, therefore a preliminary measurement is very important! 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 (exceptional case 6 mm!)
Element 
Position 
6 mm 
4
mm 
3,2
mm 
2,4
mm 
Reflector 
0 mm 
1032 mm 
1034 mm 
1037 mm 
1040 mm 
Radiator 
355
mm 
993 mm (6 mm) 
998
mm 
998
mm 
998
mm 
Director 1 
640 mm 
950 mm 
959 mm 
963 mm 
968 mm 
Director 2 
1240 mm 
929 mm 
939 mm 
944 mm 
949 mm 
Director 3 
1780mm 
896 mm 
907 mm 
912 mm 
919 mm 
Version 2: The stacked 5Element 25Ohm2mYagi, Boom 200 cm Gain of each Yagi is 9,1 dBd, F/B 27 dB 3dBangles hor = 47,2°, ver = 56,8° Gain of the stacked array 12,1 dBd 3dBangles hor = 47,8°, ver = 24,2° Stacking distance is 2,30 m

The construction of DK5EW and DF8GH for the ContestStation DA0Y in JN48MB 
Lengths and positions of the elements
Position 
8 mm  6 mm 
4
mm 
3,2 mm 
2,4 mm 

Reflektor 
0 mm 
1036 mm  1040 mm 
1040 mm 
1042 mm 
1044 mm 
Radiator 
345
mm 
978 mm  982 mm 
989
mm 
988 mm (4mm) 
988
mm 
Direktor 1 
735 mm 
926 mm  934 mm 
945 mm 
948 mm 
953 mm 
Direktor 2 
1410 mm 
922 mm  930 mm 
942 mm 
944 mm 
950 mm 
Direktor 3 
1970mm 
891 mm  898 mm 
908 mm 
914 mm 
920 mm 
With the lowest antenna 6 m above ground with medium conductivity and stacking distance of 2,30 m the gain of the array is 20 dBd! The pattern shows an elevation angle of 3° and a 3dBangle of 2,8°!
