The difference between Antenna and Transmission line

[Blilix]

I have a question about the input impedance of the antenna. Can I use the model for transmission line to analyze the input impedance of the antenna?

Also, what makes antenna different from transmission line?

Thank you.

 

[John_li]

Some Book introduce the transmission line to analyze the input impedance,it is not accurate.Cavity model to analyze is ok

 

[b4bb4ge]

The difference between the two is a transmission line holds the fields within, while a antenna is designed to release the fields into free space.

 

[kspalla]

Can I use the model for transmission line to analyze the input impedance of the antenna?

Should be ok but we need to alter the load impedance to free space.

Also, what makes antenna different from transmission line?

Both are same. Transmission line also has the radiation but it is mainly intended for low loss and load is 50 ohm. so restrict on radiation , conductor and dielectric loss.
Where as In antenna we need to radiate here we do not say radiation loss. How ever we look for low conductor and dielectric loss
Hence both are same. "The transmission line that radiates is nothing but the antenna" How ever we look the parameters like gain beam width etc. leads in development of transmission line/antenna to meet the requirements. Hence the antenna domain.

 

[Azulykit]

A simple way to think of the two devices is this: An antenna has but a single port and a transmission line has two.

Another non-obvious difference is that for very wide separations a pair of antennas has less loss than a transmission line.

 

[AN56]

There are several type of antennas by mean of radiation method. one type is transmission line type antennas which can be precisely modeled this way. But there are many other types (like antennas who couple to the air by progressively changing the impedance) which could not be modeled easily and precisely by simple TL models.
you can find more information in antenna literature books.