resistive matching network
It is a very simple problem, but I am having some trouble with it.
I have a 600 Ohm generator load, and a 50 Ohm terminating load.
When looking into the box on either side the impedance has to be matched.
The 'box' has an attenuation of 3 dB and all of the elements have to be passive. The voltage source is a sine wave with an frequency that theoretically can range from 0 Hz to infinity.
We are supposed to make the innards of the box to these specifications. To me it looks like a matching network for a phone system, but I don't understand exactly how I am supposed to make the matching system. I thought about using a isolated transformer approach, but I'm pretty sure that their is a simpler way to solve the problem.
Thanks for the help
You can not make a passive attenuator, using resistors alone, that simultaneously has 600 ohm inpedance at one port, 50 ohms at the other port, and only 3 dB of loss. You can, using series and shunt resistors, get the two impedances to match, but the loss will be much greater than 3 dB.
So you are going to have to use some sort of reactive matching, which would be narrow band, or a 600ohm to 50 ohm transformer and a resistive 3 db pad, or something like that. Unfortunately, you can not buy a transformer that works from ohz to infinity!.
Good luck
Added after 2 minutes:
A passive (resistor only) matching attenuator apparently will have at least 16.63 dB of loss:
http://chemandy.com/calculators/matc...calculator.htm
Many companies, such as minicircuits, make transformers that go between these two impedances.
Thanks for the responses!
I worked out some of the numbers on the purely resistive attenuator and you are right in order to achieve a match between 600 and 50 ohms you need have at least a loss of 16 dB.
I think it just impedance transformer like the balun in TV etc.
You better use inductive transformers for this application
How big is the size of your "black box"? you can easily use a low pass filter (LC for example) to make the transformation.