>> Okay. Now, let's talk about the amplifier block.
The amplifier block right here is used to make the signal bigger
because it wasn't big enough when it
came through the antenna. This is the antenna.
This impedance is matched to the line,
and the amplifier, when you purchase it is already impedance matched as well.
But the amplifier right here,
you'd expect that only the two terminal device like the signal comes in,
goes to the amplifier and comes out bigger than it was before.
But Amplifiers at high frequency needs to be well-grounded.
These two little wings right here are used for grounding.
You see that there are a lot of holes where pieces of wire had been
soldered down to create a really good ground for this amplifier.
If you don't ground the amplifier really well,
could it oscillates instead of amplifies, of course that's no good.
Now, the reason that happens like
one little wire connected down to the copper on the bottom.
That's not enough for a ground at high frequency.
That's because when I do that,
it acts like an inductor,
instead of acting like a ground.
So we have to put lots of holes
and ground lines down in order to fully ground this amplifier.
Otherwise it acts like an inductor to ground
instead of a short circuit to ground.
Now, an amplifier needs to have external powers.
So right here is where the external power
is going to be plugged in for this particular device.
Now, the external power is going to be DC,
whereas this is obviously an AC sinusoidal signal going through this line.
We need to be able to separate them.
So we don't want the DC getting out here to go along with our AC signal.
We put a capacitor right here,
and another capacitor right there to block the DC signal
so that it won't be mixed up with our AC signal that we want along this line.
We also put an inductor right there. You see that inductor?
That's used to keep the AC signal out of our DC circuit.
So here's the inductor block,
here is the capacity blocks.
This is a DC block,
that's an AC block.
This piece right here is a little resistor,
a little surface mount resistor.
These are called surface mount parts.
That's a little resistor that's used to help to create this amplification.
So there's a amplifier block.
The amplifier comes pre-match to
this 50 ohm line so I don't have to do any impedance matching.
I just have to be sure that the AC and
DC are kept separate for this amplifier block.