# Electrical length while designing a klofenstein taper

1. ## Electrical length while designing a klofenstein taper

Hi,

I am designing a klophenstein taper but I am stuck as to how to calculate the electrical length. My friend who has calculated the electrical length in another case has me confused.

Frequency= 2 GHZ

total taper length = 77.8mm

Ee = 3.27 of the dielectric of the microstrip

27 step klofenstein impedance transformer

and the electrical length he calculated or used in his design was 12.5055

If you could tell me how to calculate the electrical length from the given information it would be very helpful.

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2. ## Re: Electrical length while designing a klofenstein taper

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4. ## Re: Electrical length while designing a klofenstein taper

Given your physical length of 77.8 mm and effective dielectric constant of 3.27 (did you use FR4 with er = 4.4?), I would expect the electrical length to be in the range:

electrical length = 77.8mm*sqrt(3.27) = 141 mm (above the cut-off frequency).

This equals a delay of about 338 degrees at 2 GHz.

It will be somewhat more because of the path along the edge is somewhat longer than the actual length of the taper. Also the effective eps depends on trace width.

What units should be behind your quoted number?

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5. ## Re: Electrical length while designing a klofenstein taper

12.5055 is in degrees... is this what you'll get?

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