Thread: Antenna design
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Old 26-Mar-2017, 8:15 PM   #19
rabbit73
Retired A/V Tech
 
Join Date: Aug 2012
Location: S.E. VA
Posts: 2,332


Quote:
Originally Posted by dbseeker View Post
To me, at least intuitively, the shorter the reflector distance, the less likely the reflected signal would be out of phase.
I was concerned about a similar problem with a 4-bay UHF bowtie antenna. As the wavefront reaches the antenna, current is induced in the elements of all four bays at the same time. However, the current from Bay No.1 has to travel along a half wave section of the phasing line before it reaches Bay No. 2. The current changes direction every half wavelength, so the phasing line is reversed to compensate for that, but isn't the current arriving too late?

The answer to the dilemma is that the currents rise, fall, and change direction in all the elements at the same time, which is another way of saying that they are in phase.



http://www.m4antenna.eastmasonvillew...0examples.html
Attached Images
File Type: jpg 4BayCurrentFlow2.jpg (47.8 KB, 2055 views)
File Type: jpg 9inbayspacingcurrent655mhz2.jpg (73.1 KB, 2082 views)
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Last edited by rabbit73; 26-Mar-2017 at 11:29 PM.
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