Hey guys, thanks for coming back to Wi Fi fundamentals with location and analytics. This course will help you to muster the air. All right, we have reached antennas part two. And antennas actually provides three things to a radio, it doesn't matter which radio is it Wi Fi, a ham radio, whatever, gain, direction and polarization. To understand it better, we have to go back and understand the ISA tropic antenna model. And I'm telling the requested signal in different directions.

Everything is relative to an ISA tropic antenna. It is a theoretical model of an antenna that sense energy equally in all directions, perfect fair. All antennas every antenna in the world takes either tropic antenna as a reference. And there again is compared to an ISA tropic radiator. Take a look at antennas spec and you will see that their gain is mentioned with the DPI value DB versus Isa tropic and let's see how it works. Let's assume that our AP has an ISA tropic antenna and let's pretend that it transmits power in eight but its signal disperses equally in all directions.

The red.is the received power one meter from the east tropic antenna transmitter. It is the lower Signal then the region do attenuation and let's assume that the power measured is too flat. Now let's imagine that we have a real directional antenna instead. Roland Turner has the same power of eight VAT, but contrast or is a tropic antenna. We have different patterns to the signal. We have the main lobe where most of the energy is focused.

We have the back lobe were signals a lot weaker, and we have the side lobes of the far field and usually represents unwanted radiation in undesired directions. Power is concentrated in different directions. Now let's assume that one meter away our direction on Anna has more power than the two VAT opposed to our Isa tropic antenna. Let's assume that He has for VAT one meter away power as we say is concentrated in a specific direction you can see the main lobe is directed towards the far and the power received is for what? one meter away. So actually where we have the ISA tropic antenna power received to that we have our directional antennas power received at four void.

So, now we say that the gain one meter away of the agreement tenor relative to our Isa tropic antenna is two times stronger. If you convert it to DPI it is you set it right at three DB I guess And that actually brings us to our first term gain, gain is the power output in a particular direction compared to the power that is produced by an ISA tropic antenna. So, if the power is one fat in an ISA tropic container and in our antenna the power is to back then we say that the gain is twice as strong, again actually focuses the RF energy. It doesn't add power to it, it focuses it as if you were playing with a balloon and stretching it into one direction. low gain transmits in all directions. high gain usually transmits in one particular direction.

Gain is bi directional. higher gain also helps us to risk Better since the beam is stretched farther. If we look at antenna patterns we can see that low gain antennas have a beam that is more very fickle in its nature. high gain antennas have a beam that is more narrow and directional. Next up antennas Part Three where we will see how polarization and directivity are added to the antennas. See you soon