Posted by Admin on March 30, 2017
Watch a demonstration that explains basically how cell phone signal booster antennas work to improve cellular reception indoors and in vehicles.
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An antenna wire is called coaxial cable. With normal power cable, notice that the lines are parallel to each other. With coax cable, you will notice that there's a shield as its outer layer. Then, there’s an insulator, and a center conductor. The center conductor is actually what runs the power to the antenna. The reason this is important is how an antenna works.
If you have two pieces of wire side by side, you have current flow in one direction and current flow in an up and down direction. The current flows cancel each other out. If you have a piece of coaxial cable, this is actually grounded on the outside. The current flows in an up and down direction on the inside. And the currents cancel each other out. How we get an antenna to work and actually radiate power is to change that.
To change that, we want to transmit that power out into the air. Once again, you have two pieces of wire. You also have current flow in both an up and down directions. A simple dipole antenna like you put on your FM stereo at home. You just take this wire and split it off to both the left and right direction. Now, we still have current flow in one direction and we still have current flow in other direction. However, if you notice, the current flows in the same direction across the plane. That allows us to generate RF energy that leaves as shown. It can be received as well.
You have two pieces of wire side by side. The electromagnetic energy that is generated from current flow cancel each other out. We have a wire (positive) and we have another wire (negative). Because one is positive and one is negative, you can't get any energy to radiate out because they cancel each other out.
However, if you separate those two wires, this would still be our speed point down there. We have current flow in one direction and in other direction. We also have current flow in direction shown and in other direction. Every time you have current flow, you also have electromagnetic energy. We have current flow into the same direction across the plane shown.
Therefore, we have an energy field that looks as shown. We have a high current point in one place and a low current point at another place but a high voltage point at a third place. When that high voltage point hits there, all that electromagnetic energy jumps off the wire and radiates out in space.
That is basically how an antenna works. Most antennas act very similar to a dipole antenna. That is what this eaxmple was about. Remember that on a dipole antenna, you have radiated energy on both sides.
A cell tower radiates energy just like our antenna was radiating energy out. Radiated energy also can be received by this same antenna. Therefore, the antenna captures that energy and then transfers it down to our feed point. Then we can run it into an amplifier. Or maybe you just plug it straight into your stereo system. Or on a car stereo, you plug it into the back of the car stereo. They all act very similarly.
If you need more explanation, please see the actual video demonstration for more information to help answer your questions.