The three port network shown above is an Unequal Resistive Power Splitter.
Power arriving at the Input port is delivered, attenuated, to the two output ports.
More power will be delivered to port 1 (dB1), and less power to port 2 (dB2).
The power ratio between port 1 and port 2 can be adjusted to any desired value by selecting the appropriate resistor values.
All ports are matched to Zo.
The table below shows a few examples of the possible combinations.

dB 1 dB 2 Rs (Ohms) Rt (Ohms) Ru (Ohms)
0.1 44.80 0.287 4317.704 50.582
1.00 24.78 2.875 406.805 56.523
3.00 15.01 8.549 111.529 77.531
6.02 6.02 16.666 16.666 OPEN CKT

Unequal splitter values for Zo = 50 Ohms.

To calculate the resistor values for any desired value of dB1, run This Program.

To see the design equations, see this article in High Frequency Electronics magazine.
Remember that the port 1 attenuation must be LESS than 6.02dB.
The attenuation at port 2, and the resistor values will appear in the boxes below.

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