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gelunmak
Antenna Theory Regular

Joined: 05 Jun 2009
Posts: 17
Location: Hong Kong

 Posted: Fri Jun 12, 2009 10:34 am    Post subject: Antenna Quality Factor (Antenna-Q) Is the Q-factor important in antenna theory? What's is defination & equation of Antenna-Q? Is it Q=fc/(f2-f1)? [fc-center freq, f1 and f2 are cutoff freq] What i understand is higher the Q, lower the bandwidth, and Q is defined as 2(pi) times the ratio of total energy stored to energy radiated per cycle. But i can only think of microstrip patch as a resonant cavity and apply the idea to patch antenna design. i.e. Increasing the substrate thickness --> increasing the radiated energy per cycle ---> decreasing the Q ---> Increasing Bandwidth! How Q related to other antennas? Bty, not sure why there is a term " 2 (pi) " in the defination? Thanks

Joined: 03 Jan 2007
Posts: 203

 Posted: Sun Jun 14, 2009 4:58 am    Post subject: antenna Q In my mind, antenna Q only deals with bandwidth. However, equally valid is the interpretation you mentioned: the ratio of stored energy to energy radiated. Some antenna engineers think about Q from this second viewpoint; but not me. The 2*pi factor in the definition is to make the two definitions numerically consistent.
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