4 FSK WLAN splitters

>> All right, now let's
talk about Power Splitter.

The splitter is used to divide

the signal that's on the line
into two separate parts.

The reason that we're going to
divide it is because I need to know

if it's 2.4 or 2.6 gigahertz.

So it's going to go into to
band-pass filters in a minute.

We call this thing a 3dB coupler,

because 3dB means that it's
dividing the power in half,

and a coupler is the same
as a splitter or a divider.

So you can use this same
circuit to either bring

signals in like here and
here and add them up,

or to put them here and
split them down either side.

So you could call it like
a voltage divider in fact, in this case.

So what we have right here is

a 3dB coupler with
a resistive element right here.

What happens is in the event
that I had things mismatched,

or very unbalanced on either side,

this resistor is going to absorb whatever
amount of the signal is imbalanced.

So the signal comes in right here,

it splits down these two lines,

and it goes into my band-pass filter.

There's another cool thing
to note right here.

See how these little quarters
have been cut off?

That's because a high-frequency quarters
radiate really well,

and that's not generally something
that you want in your circuit.

Now, there's one form of 3dB coupler.

Here is another form of 3dB coupler.

What you can see right here is that we have

a 50 Ohm line that goes
into two 100 Ohm lines.

That 200 Ohm lines are in parallel,

so 100 in parallel with a 100 would be 50.

So this is match 50 onto
this set of 100s right here.

Once you take microwave engineering,

you're going to find out that these are
actually quarter wave transformers.

This is a quarter of a wavelength
long at 2.4 gigahertz.

This is a quarter wavelength
long at 2.6 gigahertz,

and they're two quarter wave transformers
going down either side,

that are perfectly
matching this 50 Ohm line

to the next set of
50 Ohm lines on either side.