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Metal sheet above antenna

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elexlearner

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couple in antenna reactive field

Hi ,

My RF module which is having PCB mounted PIFA antenna (2.4GHz) is near to the metal sheet which is of dim 10mm X 5mm.
1) What precautions should i take to minimize the losses.
2) Should i make slot in sheet
3) what should be the orientation of the antenna

I would be great if anybody can give some provide some document on this.
 

Hello,

I also had the same situation. As far as I found, you need to follow trail and error method.

May be your pattern can become directional rather than omni directional, the slot you mean on the metal sheet?

which simulator are you using?

--Hanuma
 

Hello smiling84,

I agree that the radiation pattern will change but "HOW", and there must be some theory behind this.

Also, what will be the effect on efficiency ?
 

The antenna pattern will change significantly only if the metal is located into the Reactive Near Field of the antenna.

Reactive near field is the region close to the antenna where the Electric-E and Magnetic-H fields are not orthogonal and anything within this region which couple with the antenna will distort the radiated pattern.

Reactive near field region is from antenna surface to 0.62*√[(Antenna_Dimenison³) / λ]

Better than any simulation is actually to measure the antenna pattern together with the nearby components.
 

As per the information from Elex,
Antenna is near to metal plate but how much near?
Are they separated in air or any dielectric?
There will raise number of questions what after the metal plate? etc.
Best thing to find the answer is to go through 3D EM simulation and find the answer.
 

thanks kspalla for your contribution,

Regarding the proximity of the metal plate... it will not be more than 30mm from the antenna.

The shield and the PCB(i.e. antenna) are separated by air.

Will it impact the performance of the antenna even if I have non-conducting material after the shield...

Can u help me with the basic guideline through which the impact can be determined.

or may you suggest some 3D EM simulator (any good freeware)??

Thanks ....
 

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