Hi Hisami,
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Thanks for the response.
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On Mon, Apr 28, 2025 at 12:58 AM, hisami dejima wrote:
> Insertion Loss: 3.5 to 3.8 dB
Does the 3 in 3.5 to 3.8 dB mean 'diveded into two port'?
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Yes. If the coupler were completely lossless, insertion gain would be -3.0 dB to the 0 degree and 90 degree ports (another words, power split equally to each output port). This coupler only adds 0.5 dB and 0.8 dB of loss beyond that.
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Japan will be on holiday for about a week so difficult to buy parts.
I want to build it on a T37-2 core.
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I think you could implement the four inductors using T37-2 cores. You would need to match the inductances as close as possible to the ideal values. Here are the ideal values:
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L1 = 3.49 uH
L2 = 0.269 uH
L3 = 14.7 uH
L4 = 1.13 uH
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C1 = 340 pF
C2 = 26.9 pF
C3 = 1470 pF
C4 = 113.4 pF
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The 14.7uH inductor would require 60 turns which seems like a lot. Two inductors could be placed in series here if 60 turns is a problem.
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For fine tuning, do I just match the frequencies?
example, L1A 3.3uH, L1B 330nH and C1 360pF are 4.4 MHz
Or is there another guide?
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Matching the frequency basically sets the phase shift through a section.? The gain through a section is controlled by the ratio of L to C. Hence, tuning a particular part will effect both gain and phase. I would start by getting component values as close as possible to the ideal values given above. Note that you can tweak the inductance of an inductor implemented on a T37-2 core by pushing the windings closer together or further apart.
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Mark
AG5RT
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