QUESTION

Question

Hello Antenova Team!

I read some of the questions and answers here and they were really helpful. Especially this one:

https://ask.antenova.com/587/sr4l034-and-sr4g008-placement-and-clearances-e-t-c?show=587#q587

Our board will be 100 mm x 53 mm. This is a view on the bottom side:

The smaller holes are mounting holes and the larger holes have studs protruding to the top side of the PCB. Which position will be better for the antenna. A or B?

In the features list of the antenna one can read: "Corner placement for ergonomic design-in". Is this a feature or is it a must? If the antenna has to be placed in the corner, then position B is automatically out.

If the position B is ok, will plastic mounting screws be beneficial for the reception?

From the other question I already know that the 8° projection line from the base of the antenna  has to be unobstructed on both sides of the PCB. But only bottom side of the antenna? Or left, right and top as well?

Best regards,

P.Jagiello

Answer 1

Hi P Jagiello,

The antenna is left or right 'handed' so for best performance it should be as close to the corner as possible. Ground plane length is also critical for sub-GHz bands, so it is often a trade-off between the two. However when we say 'corner of the PCB' in fact it's the corner of the ground plane, so you could mount the antenna in the centre of the short edge if you cut back the ground/copper to the side of the antenna. An example is shown below including an extension to the ground plane.

The 8 degree exclusion zone applies in all directions, however this is not usually so critical to performance. We offer a design review service, tailored to your project needs and can help you at every stage right through to MP, please contact techsupport@antenova.com to get in touch with your regional representative if you would  like to take advantage of this service.

Many Thanks

Steve

Comments

Hello Steve,

thank you for the answer! What is the recommended length for the cut back of ground/copper?

Can there be components placed directly under (or in this picture above) the cut back?

Best Regards,

P. Jagiello

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Hi P Jagiello,

The cut back should be as long as possible, but the positive effect of the length of cut back can be considered a curve i.e. the effect is less as the length increases. As a general rule I'd recommend at least 30mm, but every mm will help. The cut back should be completely clear of any copper, components or metal/conductive/reflective parts.

Many Thanks

Steve

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Thank you very much!

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Dear Steve,

these are our final layouts. Is it better to have a cut back of nearly 28,6mm

or is it better to move the antenna to the side, have no artificial cut back, but two holes in the path?

The smaller hole is for the mounting screw. The bigger one has a metal stud protruding to the other side. I suspect, that the upper option is better, but I wanted to ask an expert.

Best regards,

P. Jagiello