More Near field or less?
More Near field or less?
(OP)
Will a patch with very high er (80) bring the near field/far field boundary closer to the antenna by concentrating the radiated field more closely to itself?
Thank you
Thank you
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS Come Join Us!Are you an
Engineering professional? Join Eng-Tips Forums!
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail. Posting GuidelinesJobs |
|
RE: More Near field or less?
It's not a concentration due to dielectric that changes the answer to your question, it's just a physical difference in antenna size. Larger antennas have a longer distance inherently to the far field region.
Two antennas of the same physical size have the same near field/far field distance. That distance isn't simply 2d^2/Lambda either, it's much closer. All depends on what you plan to do.
d^2/Lambda has only 1/2 dB inaccuracy compared to 2d^2/Lambda for standard antennas being tested.
0.4d^2/Lambda distance from the antenna is typically the peak power density. Good to know if you are transmitting and worry about burning up a radome or human. i.e. if you make a large radome for a smaller transmit antenna, spacing it away from your antenna might burn it up if you put it 0.4d^2/Lambda away.
kch