| Stacking with Coax | Stacking with Power Splitters |
Stacking with homemade Power Splitters (DK7ZB)
Splitters available by DJ3MF, e-mail: kh-druecker@onlinehome.de
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The basis of the power splitters/combiners is a construction of a square tube for the outer conductor and a round tube for the inner conductor. It forms a quarterwave coaxial impedance transformer. The relation D/d influences the resistance/impedance of the splitter. As with the stacking by coax-cables the impedance transformation will be made with lengths of lambda/4. A halvewave-splitter consists of two quarterwave-splitters in parallel.
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A very good tool to construct power splitters is the program "AppCad" .The program is freeware,
download at http://www.hp.woodshot.com
This is a screenshot of "AppCad", you can calculate all parameters for the construction of a power splitter.
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ZE = Z02 / ZA Z = Z0 (see AppCad)
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Types of power splitters
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The λ/4-power splitter (2-way) = Type 1a |
The λ/4-power splitter (4-way)= Type 1b |
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The λ/2-powersplitter (2-way) = Type 2a |
The λ/2-powersplitter (4-way) = Type 2b |
Attributes of the Power Splitters
|
Type |
Ways |
Length |
ZE |
ZA |
Z0 |
|
1a |
2x |
λ/4 |
25Ω |
50Ω |
35,4Ω |
|
1b |
4x |
λ/4 |
12,5Ω |
50Ω |
25Ω |
|
2a |
2x |
λ/2 |
50Ω |
100Ω |
70,7Ω |
|
2b |
4x |
λ/2 |
25Ω |
100Ω |
50Ω |
Lengths of the inner Tubes (d) for the Bands 2m, 70cm and 23cm
|
Amateurband |
Principle |
Length
inner tube |
|
2m |
λ/4 |
520mm |
|
70cm |
λ/4 |
173mm |
|
23cm |
3λ/4 |
189mm |
What dimensions you use for D and d depends on the sources you have in your country. Use AppCad to calculate suitable power splitters. For Germany I have some combinations in the tables:
Table 1: λ/4
|
Type |
Square |
Inner (D) |
Round Tube (d) |
Z |
|
1a |
29,5x2,4mm |
24,7mm |
15mm |
34,4Ω |
|
1a |
23,5x1,5mm |
20,5mm |
12mm |
36,6Ω |
|
1a |
19,5x1,5mm |
16,5mm |
10mm |
34,6Ω |
|
1a |
30x2mm |
26mm |
15mm |
37,5Ω |
Table 2: λ/4
|
Type |
Square |
Inner
(D) |
Round
Tube (d) |
Z |
|
1b |
25x2mm |
21mm |
15mm |
24,7Ω |
|
1b |
19,5x1,5mm |
16,5mm |
12mm |
23,7Ω |
Table 3: λ/2-Splitter
, 2-way, Type 2a, needed Z=70,7
|
Type |
Square |
Inner
(D) |
Round
Tube (d) |
Z |
|
2a |
29,5x2,8mm |
24,7mm |
8mm |
72,1 |
Table 4: λ/2-Splitter
, 4-way, Type 2b, needed Z=50
|
Type |
Square |
Inner (D) |
Round Tube
(d) |
Z |
|
2b |
30x2mm |
26mm |
12mm |
50,9 Ω |
|
2b |
25x2mm |
21mm |
10mm |
49 Ω |
Table 4: λ/4-Splitter
, 3-way, Type 1c, needed Z=28,9
|
Typ |
Square |
Inner (D) |
Round Tube
(d) |
Z |
| 1 c | 25x2 m | 21 mm | 14 mm | 28,9 Ω |
|
1c |
29,5x2,4
mm |
24,7 mm |
16 mm |
30,6 Ω |
Practical Construction
It is not easy to connect the inner tube to the coax-sockets. The best way for all materials (you cannot solder aluminium!) is shown in the pictures below:
Splitters built by Piotr, SP5MG
The measured data of the splitters by Piotr, SP5MG
