input power of antenna

May I ask a stupid question ?

An input power for antenna is DC or AC ?

Why is using this type of input ?

Thanks for any comments.

An antenna is feed with RF (Radio Frequency) signal, which actually is AC.
Sound funny but at the very beginning of the radio there were spark-gap transmitters using DC voltage.
http://www.vistech.net/users/w1fji/spark.html

http://www.vistech.net/users/w1fji/spark.html

This link is't work .

I have some idea , but I don't know if it's right .

For example :

antenna operation for 2.4GHz band

1. Input 2.4GHz signal for an antenna

2. DC signal input for an antenna , and it gets 2.4GHz resonance frequency for operation

What's discription above is right ?

I have searched some antenna specification in network , but many papers

say that input DC (like 12V DC) power to the antenna .

some links:

http://www.ferret.com.au/articles/a0/0c03eba0.asp
http://www.smarthomeusa.com/Shop/Rem...-Transceivers/
http://www.northcountryradio.com/Kitpages/actant.htm


I am confused with it .

Hope anybody help me to understand it. Thanks a lot .

Dear pfijk,

Description (2) is correct, and so is vfone. An antenna is nothing more than a piece of metal that recieves and transmits RF signals, which is also an AC source because oscillation along the antenna length is needed. Briefly scanning the links you've given, they just indicate that these packaged antennas consume that amount of power to work. I'm sure these gadgets also have an input port for AC signals (for the transciever case).

Hope this helps,
Dave

The dc voltage (12V, 5V and so on) that confuses you is used as a supply voltage to the antenna amplifier(s) .. see picture below ..
It has nothing to do with AC RF signal ..

Regards,
IanP

I understand it .

Appreciate heedavid and IanP for your ardent help .

Have a nice day for you !
:D