Meaning
A designated region on a printed circuit board remains entirely clear of copper traces, ground planes, and metal components to prevent interference with wireless signals. Within this specified area, known as an antenna keep-out zone, no structural materials or traces can be placed during layout. This volume of space must be maintained in three dimensions to allow the radiator to achieve its designed impedance and radiation pattern.
Layout Constraint
Board designers position the transceiver at the edge or corner of the board to minimize the required clearance volume. Ground planes must terminate exactly at the boundary of the antenna keep-out zone to avoid capacitive loading. Any metal screws, shielding cans, or bracket mounts placed too close to the radiator will distort the beam pattern and reduce the transmission range.
Impedance Matching
The absence of nearby conductive material ensures that the antenna matches the characteristic impedance of the feed line. Deviation from this layout rule shifts the resonant frequency of the antenna, causing signal reflection and power loss. This shift degrades receiver sensitivity and increases power consumption during transmit cycles.
Enclosure Design
Non-metallic plastics and polycarbonates must be selected for the portion of the housing that covers the radiation area. The distance between the active radiator and the inner wall of the product enclosure is controlled by mechanical brackets. This alignment maintains the dielectric environment required for the wireless module to operate at peak efficiency.
