antenna matching

Matching circuits are used for matching Antenna impedance.
My question is whether this will affect the performance of the antenna?in the sense this additional circuit will change the resonant frequency ?
My confusion is regarding the difference between Antenna Loading and Matching circuit.

i think antenna matching , is circuit inserted between the antenna and the PA , to make total power transfer to antenna and this increase the system efficiency ,

so it shouldn't change the antena resoanse freqyancy

khouly

matching circuit affects the bandwidth of your antenna depending on how bad the matching of the antenna itself.

thanks guys

Now i got some idea.I dont know whether is right r wrong?

1)Matching circuit is used for maximum power transfer from other circuit to the antenna.this circuit is outside the antenna.

2)Antenna loading is used for compensation of electrical lenght of the antenna.this will be with in the antenna.

hi,
as said in the previous reply matching is per maximum power trasfer surely, but i don't think it doesnot affect characteristics of antenna but to a minimum extent we can tolerate

It is not clear what you mean by antenna loading.
must another of those term that have different
meaning.

Antenna loading is nothing but adding inductor or capacitor to vary the electrical length of the antenna.
eg.
For low frequency monopole antenna ,Inductor will be added between feed point and radiator inorder to reduce the electrical length of the antenna.

Read the book " Reflections" by Maxwell , ARRL publication.
It will clear all your doubts regarding antenna matching & tunning.
There is lot many things than simple power transfer.
This book says SWR should never be 1!

Now I understand.....
If you design an antenna no always the antenna has the ideal
impedance. For example, the spiral antenna has an impedance
of about 150 to 200 ohm. So there is need for a matching circuit
to an transmission line of 50 ohm.
Loading makes the overall size of the antenna smaller while keeping
the antenna resonant at the same frequency. Of course will change
the impedance but hopefully for not much, that is why is keepping
the antenna resonant.

So, loading and matching are interrelated but they are two
different things.