Near vs. Far Field - RF Cafe Forums

The original RF Cafe Forums were shut down in late 2012 due to maintenance issues - primarily having to spend time purging garbage posts from the board. At some point I might start the RF Cafe Forums again if the phpBB software gets better at filtering spam.

Below are the old forum threads, including responses to the original posts.
-- Amateur Radio
-- Anecdotes, Gripes & Humor
-- Antennas
-- CAE, CAD, & Software
-- Circuits & Components
-- Employment & Interviews
 -- Miscellany
-- Swap Shop
-- Systems
-- Test & Measurement
-- Webmaster

Jose Arrina
 Post subject: Near vs. Far Field
Posted: Thu Mar 30, 2006 9:23 am 
 
Lieutenant
User avatar

Joined: Thu Mar 30, 2006 9:01 am
Posts: 4
Hi guys,

I have searched around the Internet for a definite definition of where the transition between near filed and far field lie. I see a lot of rules of thumb, and they vary from something like lambda/4 to 10*lambda. There has to be a truly technical definition that the measurement standard houses use. If would appreciate it if you could point me to one or more documents that declare ye verily this be the standard ;-).

Thanks, and have a good day.

_________________
... Jose' Arrina
 
   
 
Kirt Blattenberger
 Post subject
Posted: Thu Mar 30, 2006 1:13 pm 
 
Site Admin
User avatar

Joined: Sun Aug 03, 2003 2:02 pm
Posts: 308
Location: Erie, PA
Greetings Jose':

A while back, Evaluation Engineering published a good article on the subject (1). I used their equations to create a calculator (2) that you can plug the DUT antenna dimension into and get a table & graph. The definition given agrees with what a lot of other field measurement papers use for the near field and far field regions. Here is another paper to consider (3); Figure 3 is a good picture of what's happening.


(1) http://www.evaluationengineering.com/archive/articles/1005/1005the_world.asp

(2) http://www.rfcafe.com/references/electrical/near-far-field.htm

(3) http://www.conformity.com/0102reflections.html

.

_________________
- Kirt Blattenberger :smt024
RF Cafe Progenitor & Webmaster
 



Posted  11/12/2012