Lowest usable high frequency

Imagine a big playground where everyone speaks a different language. Some kids can hear each other's voices very clearly and some can't, depending on how loud and high-pitched the other kid's voice is. The same thing happens with radio waves.

Radio waves are a type of energy that travels through the air, like sound waves travel through the playground. Some radio waves have a very high-pitched sound, and some have a lower-pitched sound. The lowest usable high frequency is the lowest "pitched" radio wave that we can use to communicate with each other.

When we send information through radio waves, we use different frequencies (or pitches) to send different types of information. For example, we might use a low-pitched frequency to send voice information like talking on a phone, and a high-pitched frequency to send data information like sending an email.

However, just like on the playground, different radio frequencies can interfere with each other if they are too close together. This can cause problems with our communication, like not being able to hear each other clearly.

That's why we use the lowest usable high frequency - it's the lowest frequency that we can use to send high-pitched information without it interfering with other frequencies. It's like finding the perfect spot on the playground where you can hear your friend's voice perfectly without anyone else's voice getting in the way.