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More Near field or less?

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Microfielder

Electrical
Joined
Feb 9, 2009
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6
Location
GB
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
 
The near to far field boundary will be closer because the patch antenna will be physically smaller due to that high dielectric loading.

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
 
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