QUESTION

Question

Dear,

We have tested "Robusta" and it works perfectly mounted onto any material with the exception of a circuit with currents under the antenna: it seems normal, I am wrong?

How we should place the antenna integrated into a circuit? How horizontally far from conductive nets? Better solid GND or copper cut-ut below the antenna?.

Our circuit is tiny in comparison with the antenna and also has other printed antennas so we are not sure if it ir viable or not using your antenna.

Placement example:

 

Thank you!

BR,

Manuel

Answer 1

Hi Manuel,

It seems the antenna is placed too close to the other antennas. If the antenna is placed on a PCB, it should be kept a minimum distance away from any other board mounted component. This distance can be defined by projecting a
5° angle from the bottom of the antenna as shown below

Are there other possible locations to place the antenna? such as other side of  PCB or the housing?

Best regards,

Yu Kai Yeung

Comments

Thank you for your answer,

won't be possible to place the antenna on the other side (there is a battery) or another place in the housing. We could move some components or even enlarge the PCB a bit to meet 5º angle requirement.
In any case I still having the doubt: how near currents will affect the antenna (high-speed nets on TOP layer)? The drawing of the antenna on top of a PCB in your datasheet shows it isolated from nets and sorrounded by GND vias in a corner of the PCB. As I said we tested the antenna on the TOP of a PCB and the currents below detuned it, even when the antenna has a solid copper plane on its bottom layer.

If possible, what would be better below the antenna in our PCB: GND plane under the antenna or copper cut-out in all the layers?,
BR,

Manuel.

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Hi Manuel,

Given the proximity of the two other antennas, I would certainly recommend enlarging the PCB as much as possible - this will also reduce potential isolation issues. Cable routing is also important, can you show how you have routed the cable?

Many Thanks

Steve