Doubts regarding on Dielctric in Microstrip line

[raju_kambar]

I have following doubts on Dilectric

(1) What is dielctric, why do we need to use dielctric in between two conductors in microstrip

(2) What is the advantage of using dielctric in microstrip

(3) Generally why do we need to use the dielctric

 

[eraste]

Hi, this is my answers :
1) Dielectric are characterized by their permitivitty epsilon. They are the medium that support lines. They could be simply air (like line make with simply two wires) or more complex like teflon, ceramic ... Thanks to a high permitivitty you can reduce the size of system (e.g patch antenna or resonnator Lambda/2 or /4 etc...). But be carreful, dielectric have loss so you have to know the Tan(delta) loss.
2) Like i say in 1) the size of the system (antenna, line...) because you reduce the size by a factor sqrt(epsilon_r). Epsilon_r is the relative permitivitty.
3) same reason. To reduce lambda.

Bye.

 

[biff44]

dielectric layers are handy between a microstrip line and the ground plane, as they keep the microstrip line from falling down onto the metal ground plane and shorting out. :roll:

 

[eraste]

very funny bif44 !

 

[Electron3]

so which dielectric material i should use to handle higher power in kw
which parameter need to look in
from substrate

 

[eraste]

Well,
The best dielectric is air. The important parameter is the break-down voltage of the dielectric and of course the geometry of your high frequencies system. For example, the maximum power transmit by a rectangular waveguide depend on the dimension and the break-down voltage of the dielectric inside. You have to avoid regions with high electric field where the voltage could be high.
Furthermore, you must be carrefull of the loss of the dielectric, i mean his tan(delta).
Good work.

 

[Electron3]

yes i got
i selected Rogers 4350 and arlon TC350 for may high power design
power 1.25kw
is it reliable
can i get results from this one
simulation and s parameter characterization completed successfully

 

[eraste]

Knowing the max tolerable electric field, you can deduce the maximum power usable.
If your simulation are agree so you can use Roger or arlon.

Bye