What's the importance of source frequency for antenna?

Hello,

I need some clarifications. Please correct me if I'm wrong. Here is my summary of the problem which I don't quit understand. The source ( feed the antenna) will attach to the antenna. Quit obvious. The only thing is to be sure to match the source to the antenna to avoid inefficiency. So, what is the ultility of the source frequency in the radiation system? Is it just a propriety of the source? For example, I have a source which operates at 500 MHz, and I attache to a horn antenna. So, to radiated efficiently I need to match its impedance to the antenna impedance. Let's say, 50 0hm transmission line to 50 ohm antenna (ideal). If I want to have a narrow band antenna or a wide band antenna, I need just to change my my antenna and I will get what I want. But, the source frequency does it have an important?

Thanks,

Mica

Most antennas are narrow band. A 500 MHz horn antenna will be at least 20 x 20 inches. If you try to use a horn antenna designed for 5 GHz at 500 MHz, almost no power will be radiated (it will not work). You have to use the right frequency range antenna for the source frequency.

Thanks for the info. So, if my generator is a ultra wide band (impulse) this means that I can use all types of antenna.

Thanks,

Mica