Reducing azimuth-elevation correlation in an antenna array structure

A wireless device comprising:

• an antenna array structure comprising:
• a plurality of active antenna elements each coupled to a respective one of a plurality of antenna ports and configured to:
• absorb a radio frequency (RF) signal transmitted by a transmitter in a frequency band;
• and
• feed the RF signal to the respective one of the plurality of antenna ports, wherein the plurality of active antenna elements is configured to form a plurality of orthogonally related antenna pairs each configured to measure a respective one of a plurality of phase difference of arrival (PDoA) angles of the RF signal;
• and
• at least one passive antenna element configured to:
• absorb and isolate the RF signal from each of the plurality of antenna ports;
• and
• decorrelate the plurality of PDoA angles measured by the plurality of orthogonally related antenna pairs.

A method for fabricating an antenna array structure comprising:

• providing a radiating layer in the antenna array structure;
• providing a first intermediate layer underneath the radiating layer, the first intermediate layer having a material with negative permeability in a lower portion of a frequency band and positive permittivity in a higher portion of the frequency band;
• providing a plurality of active antenna elements in the radiating layer and coupling each of the plurality of active antenna elements to a respective one of a plurality of antenna ports;
• configuring each of the plurality of active antenna elements to absorb a radio frequency (RF) signal transmitted by a transmitter in the frequency band;
• configuring each of the plurality of active antenna elements to feed the RF signal to the respective one of the plurality of antenna ports;
• providing at least one passive antenna element in the radiating layer;
• and
• configuring the at least one passive antenna element to absorb and isolate the RF signal from each of the plurality of antenna ports.