The communication review meeting with Jin continues after lunch.

"In the case of light, the problem was that it was too linear. ......"

Jin opened his mouth.

"What would happen if we made it into radio waves?"

It is hard to imagine because it is invisible.

Reiko answered.

"Father, I can see radio waves too, can't I?

"What?"

Reiko said, "I can see radio waves.

"I didn't tell you, but when your father enhanced my vision, I was able to detect <> and see <>. ......"

"......What did I do 400 years ago?"

Jin was puzzled, but when he thought about it, the function was not so strange.

Since Reiko can detect magic, it would be strange if she can't detect electric and magnetic fields. Jin decided to think so.

And if she can see electromagnetic waves when she uses <, she should be able to search her surroundings like a radar .......

In other words, Reiko now has a radar-like function, albeit a limited one.

"What is the difference between radio waves radiated from an antenna and those radiated by magic?"

I was eager to ask him for the sake of future study.

"I don't know what a radio wave radiated from an antenna is, so I can't say.

"That's right. ......"

"Radio waves radiated by magic spread out in a cone shape, right? It's no different than light."

I see.

Jin dredged up a corner of his memory, "I thought electromagnetic waves with a wavelength as short as a millimeter wave had a high linearity.

"Then, I wonder if it would be easier for the receiver to use a radio wave with a longer wavelength ......."

In Jin's memory, the TV antennas of the houses in the mountains (in the analog era, of course) were all pointed high toward the sky.

Jin recalled that this was because TV signals are highly linear, and it is difficult to receive them in the shadows of the mountains .......

On the other hand, AM radio signals could be received without much difficulty. This is because radio waves with longer wavelengths can be transmitted to the shadowed side of the mountain, even if there are obstacles in the way.

"Let's try it around there."

Long waves, as the name implies, have longer wavelengths and thus require antennas for both transmission and reception.

The wavelength is so long that it is also called .

This makes it difficult to use, but not for Jin and the others.

"Well, then, let's consider that line of thought!"

Reinhardt said with great enthusiasm, as if he wanted to make a prototype as soon as possible.

"Good idea!"

Saki agreed.

"I'll leave that to the experts."

"Likewise."

Bertsche, Vivian, Toa, Rodrigo, and the others seemed to be on the sidelines.

* * * *

"Change the parameters of the < here at ...... and you're good to go.

Jin has just finished modifying the <, which is not a flashlight.

"This should produce at least a medium wave. Reiko, check it out."

Jin turned on the flashlight and aimed it at the void.

"How is it?"

"Yes, it is. ...... but the cone has a top angle of about 170 degrees.

That means that the cone is spreading toward the front, not toward the directionality. But Jin could imagine the cause.

"Oh, I see. There is no way such a lens can converge."

The lens used to converge visible light had absolutely no effect on the mid-wave.

Incidentally, when it comes to very long waves, it penetrates through various objects.

On the other hand, they are more susceptible to noise in nature, such as static electricity. ......

"We can use the lens as a magi material and make it magically converge," Saki advised.

Saki then offered some advice.

"Jin, why don't we use light-attribute magi crystals?"

"Oh, that might work. Let's give it a try."

As it turned out, it worked out perfectly.

"Well, it seems that the focal distance can be changed by the strength of the magic power applied to the magi crystal.

Saki said happily.

"Yes, this is nice. But isn't it a little too costly?"

Magi crystals of the light attribute are quite expensive.

"Well, if it's only for air traffic control at airports, it's good, isn't it?"

Reinhardt said, "It's better to have a lot of people using it than to have it spread so widely that it gets out of control.

"That's one way to look at it."

If it is limited to airports in each country, the number could be less than 100.

"What about the receiving end of ......?"

Elsa asks. It is true that the number of receivers would be countless.

"Besides, it's going to be a one-way street," Hannah says with some regret.

Hannah says a little regretfully.

Indeed, not being able to hear the visitor's reply is a problem, everyone thought.

"Well, there are still many problems to be solved.

But Jin's face looks happy as he replies, "Well, there are still many problems to be solved.

He was so happy because he had never thought that he would be able to have fun with again.

"Well, I wonder if we can find some clues if we consider the conditions for sound waves to travel far and how to pick up sounds from far away?"

Hannah suggested an approach from another direction.

"Well, ...... I wonder if we could make good use of wind attribute warding."

Since we are bound to use only techniques, it is difficult to come to a conclusion even though Jin and the others are all working together and pooling their wisdom.

However, it is a fun and meaningful time.

There are no restrictions as to when.

As a proof of this, the faces of everyone in the Jin Family were uniformly cheerful.

However, it is not always easy to create something new.

"...... hmmm ......"

As the makers were groaning, Meene came in,

"You should take a break when you are lost in thought," she said.

She said to them, "You should take a break when you're lost in thought.

There is tea ready for you in the vestibule.

"Thank you, ...... mother."

"This is very kind of you."

Everyone, a little tired, thanked Meane and left the institute for a change.

"Oh."

It was a nice day to take a break outside, and everyone sat down on a chair or lay down on a picnic sheet on the lawn.

"The tea is good, and the rice crackers are delicious.

"The sweetness of the red bean paste is indescribable. It soaks into my tired head.

"Fresh juice is the best!"

Seeing everyone doing what they wanted with their drinks and food, Jin felt truly relaxed.