50 ohm PCB antenna track impedance

Mar 24, 2010 2 Replies
C

I am designing a PCB which will use a GPRS modem. The connection between the Antenna SMA connector and the GSM modem is via a 20mm 50 ohm PCB track. This is a two layer 1.6mm thick 1 oz copper PCB and the



50 ohms impedance is achieved with a 260 thou track in a ground plane with 8 thou clearance over a solid ground plane,. Do I really need to get the PCB impedance checked by the pcb manufacturer as my current supplier cannot do this for prototypes, will it have much effect for a track of this length at 1900MHz. Thanks
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C

Sorry, got my dimensions wrong, Track width is 45 thou, ground clearance 7 thou (coplanar) on a 63 thou pcb with bottom ground plane.

1 oz pcb copper!
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I

"comp.zrch.embedded" wrote in news:88ba0e9b-d70c-4425- snipped-for-privacy@19g2000yqu.googlegroups.com:

The answer depends on things like: How close to 50 ohms do you need to be? How closely can your vendor control track width? dielectric thickness? What is the relative permittivity of the dielectric? How well controlled?

Your wavelength is about 158 mm. Your track length is is a fraction of this. Is 50 ohms relevant? I don't know.

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