Antenna - Theory .com: The Antenna Site

Antenna Basics Antenna Types Smith Charts Antenna Measurements

antenna-theory.com :: View topic - Antenna Quality Factor (Antenna-Q)
antenna-theory.com Forum Index antenna-theory.com
Antenna Theory
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Antenna Quality Factor (Antenna-Q)

 
Post new topic   Reply to topic    antenna-theory.com Forum Index -> Questions Related to Antenna Theory
View previous topic :: View next topic  
Author Message
gelunmak
Antenna Theory Regular


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

PostPosted: Fri Jun 12, 2009 10:34 am    Post subject: Antenna Quality Factor (Antenna-Q) Reply with quote

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
Back to top
View user's profile Send private message
admin
Site Admin


Joined: 03 Jan 2007
Posts: 204

PostPosted: Sun Jun 14, 2009 4:58 am    Post subject: antenna Q Reply with quote

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.
Back to top
View user's profile Send private message Send e-mail
Display posts from previous:   
Post new topic   Reply to topic    antenna-theory.com Forum Index -> Questions Related to Antenna Theory All times are GMT
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group