Quarter Wave Transformer
But the length of the quarter wave transformer will exceed the substrate size of the antenna. So is it necessary to have lamda/4 length for the transformer. I read that the width of the line is important for getting the right impedance. please help....
I can assume that your antenna has its dimensions longer than a half wavelength. Then you can use the same or a similar substrate to make the quarter-wave transformer as needed. Any handbook on striplines will give you the information of the line width defining lined impedance.
Having no information from you on the operating frequency, I can only suggest that impedance transformers can also be made with lumped elements and small size. As you do a project, you must study well everything you need to succeed.
I think using a Stepped impedance Resonator is the only way for u to reduce the size.. Atleast to wt i can think of now..! Stepped impeance resonators (SIR) are made to give behaviour of a certain electrical length by a reduced electrical length in proportion to the ratio of two impedance steps..! U'L find info on it easily..!
Do reply if it works..!
Regards..
We are designing a patch antenna loaded with a csrr structure to reduce the freq.
the operating freq of the simple patch that we r using is 10ghz and after we load it with a csrr structure the freq is reduced to 3.28ghz.The csrr structure is placed on the ground plane.
patch size:-
L=6.4899mm
w=9.1287mm
substrate size:-
l=16mm
w=19mm
I do not know what "csrr" structure is. But as you use a dielectric substrate, the lambda is shorter than that in air. Therefore you can use the same substrate to make the quarter-wave transformer.
You can use meanders in the line of the transformer.
Regards
Z