Effects of embedded antennas on iron (III) oxide-enhanced building materials at 5G microwave frequencies

Abstract

For the application of 5G, the sub-6G band, in urban and rural areas, the study focuses on the effects of embedded antennas in iron (III) oxide enhanced building materials. Uniformly manufactured mortar and cenosphere bricks with different concentration of iron (III) oxide are tested to evaluate their electromagnetic wave propagation behaviour. The 2\% iron (III) oxide enhanced brick shows the best propagation performance for the $S21$ parameter, which is -4.3 dB and higher than the 0\% and 4\% iron (III) oxide enhanced bricks. The cenosphere group shows an average gain of 0.65 dB at 3.5 GHz and it can be considered as a valuable filler for the building materials.

Antennas before and after being embedded in those bricks are examined to show that the embedding process helps to reduce the quality factor. The 6\% iron (III) oxide embedded antenna shows the highest reduction of quality factor of 25.35, whose original quality factor is 49.43. The bandwidth of the embedded antennas are expanded by 50 MHz at most. This characteristic has been observed on the 0\% and 6\% iron (III) oxide enhanced antennas. Besides, the embedded antennas exhibit drawbacks like shift of resonant frequency and distortion of the irrelevant band.