asking about quarter wavelength transformer?

[tienthanh0505]

can anyone tell me whether the microstrip quarter wavelength use guided wavelength or free-space wave length? i read some documents and some of them say it is guided and the others say it is free-space? please help me i'm so confused.

 

[volker@muehlhaus]

Guided wavelength. All this line impedance transformation and Smith chart stuff works on guided wavelength.
Free space parameters only matter when you have medium free space.

 

[tienthanh0505]

Thank you for your reply. SO, if i have an array antenna and the distance between elements is half wavelength, that "half wavelength" is guided wave length too, isn't it?

 

[FvM]

If you are referring to the array antenna characteristic, the answer is no. The characteristic is determined by the free space distance of elements.