DWM3000 suggested layout

I’m laying out a host PCB for the DWM3000 Transceiver Module, and I’m looking for clarification of the layout guidelines on page 19, figure 10 of the data sheet. The data sheet reads as follows:
“In Figure 10 below, ‘d’ should ideally be 10 mm.This gives the most vertically polarized radiation pattern. As ‘d’ is increased from 10 mm the degree of vertical polarization reduces.”
My question is, what is the effect on polarization if ‘d’ is decreased from 10 mm? We’d like to keep the board size as narrow as possible but not at the risk of reduced performance.
Thanks in advance for your assistance.

It seems that you are referring to the distance ‘d’ between the antenna trace on the host PCB and the ground plane.

According to the data sheet, if the distance ‘d’ is decreased from 10 mm, the degree of vertical polarization will increase. This means that the antenna’s radiated electromagnetic field will have a stronger vertical component, and a weaker horizontal component.

It is important to note that the optimal value of ‘d’ will depend on the specific design and performance requirements of your system. In general, a larger value of ‘d’ will result in a more omnidirectional radiation pattern, while a smaller value of ‘d’ will result in a more directional radiation pattern.

If you are trying to minimize the size of the host PCB, it may be necessary to reduce the value of ‘d’ below the recommended 10 mm. However, this may also result in reduced performance of the antenna, such as reduced gain or reduced operating range. It is therefore important to carefully consider the trade-offs and ensure that the antenna still meets the performance requirements of your system.

Keonte45, thank you for your helpful response.

You’re welcome, Coffeeman. Glad I could help.

While having the PCB extend 10cm outside the module will be different to the PCB only extending 5 cm past the module the difference between air and empty PCB is minimal. So it depends on what would you be placing there instead.
If you have a PCB that extends 5cm on each side and then a plastic housing and air the impact will probably be minimal. If instead you had something metallic or RF absorbing (like a hand) within that 10cm distance then it’s going to have a significant impact on performance.

AndyA thanks for the information. Very much appreciated!