QUESTION

Question

Hello.

I have a question about HOST PCB size of Zhengi SRFC015.

I check the HOST PCB size in datasheet of Zhengi SRFC015.

I understood that the PCB size is irrelevant and that a connector is required.

So, Can I configure the antenna like HOST PCB(Main PCB) - Matching circuit - Connector - Antenna?

Please, if possible confirm the infomation.

Thank you.

regards.

Answer 1

Hello Kdh5389,

It is best to have the matching close to the antenna as the connector is usually 50 ohms impedance and will throw off your matching. It's like driving a car from the back seat facing backwards looking through a mirror to see where you are going. You will also need to have the connector set up as a switched connector adding loss to your RF path otherwise the connector will be constantly open circuit.

Best regards,

Geoff S.

Answer 2

I understood that the PCB size is irrelevant and that a connector is required.

Every type of monopole antenna requires a ground plane depending on the lowest frequency to be radiated. Flex PCP antennas like Zhengi with cable are monopole antennas. If the ground plane of your PCB is so small, the antenna will not work properly.
First, build up an empty PCB with the coaxial connector and the chosen antenna and measure the return loss of the antenna with a Vector Network Analyser. Keep in mind that a battery affects the size of the ground plane. Keep in mind that a display or other metallic objects will influence the antenna.
If you do not have a Vector Network Analyser, you can ask an external consultant to do the work on the antenna.
I am such a consultant. Harald.Naumann(at)LTE-Modem.com