A frequency reconfigurable antenna with a simple design structure and biasing circuit is presented. The antenna is able to configure its frequencies to operate either in multiband or wideband modes. The antenna is fed by a coplanar waveguide transmission line. The reconfiguration characteristics of the antenna is achieved by using PIN diode switches. The operating frequencies of the multiband mode are designed within the wideband mode operating range, from 2 to 6 GHz. Both simulated and measured results of S11, radiation pattern and realized gains are verified. The antenna allows a degree of freedom in providing the frequency reconfiguration from multiband to wideband mode and vice versa.

The incoming 5G technology requires antennas with a greater capacity, wider wireless spectrum utilisation, high gain, and steer-ability. This is due to the cramped spectrum utilisation in the previous generation. As a matter of fact, conventional antennas are unable to serve the new frequency due to the limitations in fabrication and installation mainly for smaller sizes. The use of graphene material promises antennas with smaller sizes and thinner dimensions, yet capable of emitting higher frequencies. Hence, graphene antennas were studied at a frequency of 15 GHz in both single and array elements. The high-frequency antenna contributed to a large bandwidth and was excited by coplanar waveguide for easy fabrication on one surface via screen printing. The defected ground structure was applied in an array element to improve the radiation and increase the gain. The results showed that the printed, single element graphene antenna produced an impedance bandwidth, gain, and efficiency of 48.64%, 2.87 dBi, and 67.44%, respectively. Meanwhile, the array element produced slightly better efficiency (72.98%), approximately the same impedance bandwidth as the single element (48.98%), but higher gain (8.41 dBi). Moreover, it provided a beam width of 21.2° with scanning beam capability from 0° up to 39.05°. Thus, it was proved that graphene materials can be applied in 5G.

Abstract-Diamond dipole antennas with textile Artificial Magnetic Conductor (AMC) sheet-like waveguide were designed to investigate the possibility of improving transmission between antennas. Fleece fabric is used as the substrate of the textile AMC while SHIELDIT fabric is used as the conductive patches and ground plane. The AMC surface is designed to resonate at 2.45 GHz with the goal to enhance the transmission between antennas. A small textile AMC waveguide sheet as well as an AMC waveguide jacket were fabricated. The S-parameters performance of the two antennas with textile AMC sheet was investigated in a free space environment and near to human body setting. The effect of different antennas' orientations was also considered. Measurements were conducted thoroughly to validate the simulated findings. Compared to free space environment, S 21 transmission between two dipoles is improved up to maximum −10 dB when having textile AMC waveguide sheet beneath them. For both off-body and on-body placements, significant transmission enhancement has been observed with the introduction of the AMC sheet-like waveguide. Directive radiation patterns with high gain have also been achieved with the proposed AMC waveguide jacket.

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A textile Artificial Magnetic Conductor (AMC) sheet-like waveguide with wire dipoles were designed to investigate the possibility of improving transmission between antennas. The textile AMC sheet is made of fleece fabric with conductive patches and ground plane made of SHIELDIT fabric. The AMC surface is designed to have in-phase reflection at 2.45GHz with the objective to enhance the transmission between antennas. The S-parameters performance of the two antennas with textile AMC sheet was investigated thoroughly. The effect of different antennas’ placement and distance was also considered. Measurements were conducted rigorously to validate the simulated findings. Results show that the S21 transmission between antennas improved significantly when having the AMC waveguide sheet beneath them. Directive radiation pattern with high gain was also achieved with the proposed AMC sheet-like waveguide.