Antenna PCB Layout Considerations

[Jan Kijonka]

Hello,

I would like to reach the maximum RF range for the ESP-12E module from esperessif. This module uses PCB Meandered Inverted-F Antenna (MIFA). What are the design consideration for the host module PCB layout ?

1) Should I place PCB FR4 material (without copper) under the antenna or should I better leave the antenna in free space (protruding from the host module PCB) ? I have two versions of the ESP-12E modules: one with the PCB thikness of 1.5 mm and the other with the PCB thikness of 0.75 mm. Are both of these module versions or just one of them adapted to have an additional thickness of the PCB under them ? If so, what is the recommended host module PCB thikness ? I take into account that the PCB thickness under the antenna affects its properties.

2) Should I place some electronics from one or both sides (x-axis) from the antenna without reducing the RF performance ? If so, what are the smalles distances of electronics placed on the antenna tip and opposite sides ?

3) What is the minimum width and length of the continuous ground plane located below the antenna for the best performance and minimum interference with the analog parts of the host module ? When I use four layer PCB, should I place the ground plane in all layers or can I use only one layer for the ground and other layers for electronic components ? How many ground vias (in which density, width and length) should I use ?

Thank you,

Jan Kijonka