# Need Formula for Percent Bandwidth - RF Cafe Forums

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jstover
 Post subject: Need formula for percent bandwidth. Posted: Thu Jul 12, 2007 6:35 pm
 Lieutenant

Joined: Thu Jul 12, 2007 6:21 pm
Posts: 2
I need the formula to calculate percent of bandwidth, as in "60 GHz, +/-5%." Can someone help?

jaslovkel
 Post subject: Posted: Thu Jul 12, 2007 6:50 pm
 Captain

Joined: Tue Jun 26, 2007 10:27 am
Posts: 14
Location: Dallas, TX
Hi jstover,

If we assume that there is a given center frequency called fc and we need to know the ranges we need to measure around fc in percentage, we can use the following formula to find the lower(fl) and higher(fh) frequencies which the percentage will allow.

fl=fc*(1-%/100)
fh=fc*(1-%/100)

So, if we assume that fc=60GHz and there is a +/- 5% bandwidth around this, then we can find:

fl=60GHz*(1-5/100)=57GHz
fh=60GHz*(1+5/100)=63GHz

I hope this is what you were asking for and that it helps you out.

-J

jstover
 Post subject: Posted: Fri Jul 13, 2007 5:30 pm
 Lieutenant

Joined: Thu Jul 12, 2007 6:21 pm
Posts: 2
 Thanks for your response. Somehow, I remembered it as being more complex than simple percentage math.

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