Antenna - Theory .com: The Antenna Site

Antenna Basics Antenna Types Smith Charts Antenna Measurements

antenna-theory.com :: View topic - How to optimize monopole length for antenna efficiency
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 

How to optimize monopole length for antenna efficiency

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


Joined: 09 Dec 2015
Posts: 1

PostPosted: Wed Dec 09, 2015 7:17 pm    Post subject: How to optimize monopole length for antenna efficiency Reply with quote

Hi,

I want to make a PCB antenna for 868MHz. Assume that I make a PCB monopole with a 70 x 70 mm ground plane and a straight trace of approx. 1/4 wavelength.

I would like to first adjust the length of the antenna trace so that it becomes as most efficient at 868 MHz as possible and then add a matching network to match it to 50 Ohm.

I have a VNA, but how do I know when the antenna length is optimized?

Shall I adjust the length until the imaginary part of the impedance is zero and then add matching to get it to 50Ohm?

Or shall I adjust the length until the impedance is close to 36.5 + j21.25 and then add matching to get it to 50Ohm?

Or something else?
Back to top
View user's profile Send private message
admin
Site Admin


Joined: 03 Jan 2007
Posts: 197

PostPosted: Thu Dec 10, 2015 7:11 pm    Post subject: Reply with quote

I would look at VSWR (Scalar measurement). Trim the length until the vswr minimum resonance is at 868 MHz. Then if the match needs further improved do the impedance matching then.
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