A novel integrated compact antenna with photonic band gap (PBG) structure, having switching capability between lower and upper bands of 5G cellular communication is proposed. The proposed antenna can operate in the lower band (3.1 GHz to 3.5 GHz) as well as in the upper band (24 GHz to 27 GHz) of 5G cellular communication. Two radiating patches for the aforementioned frequency bands are developed in the same structure. A small patch for the upper-frequency band is inserted into a rectangular slot made in a large patch of the lower-frequency band. Both patches radiate at different times with the same ground. Two PIN diodes have been used to excite both patches at different times. The results indicate that the antenna has higher gain and wider bandwidth than the conventional antenna without a PBG structure.
INTRODUCTIONWireless communication technology is evolving at a fast pace. 5G is a next-generation wireless communication technology, which provides support for very high speed data transfer. This technology would enable internet of things (IoT) and robotics applications to work effectively [1,2]. With 5G, an integrated compact antenna is required that can transmit and receive the signal within the proposed lower and upper bands. Along with the conventional lower band, 5G technology also works in an upper band (millimeter wave) to achieve a larger bandwidth, higher data transfer rate, and low latency. Many researchers have proposed 5G microstrip antennas for lower and upper bands respectively [3][4][5][6][7][8][9][10][11][12][13][14]. Recently, photonic band gap (PBG) structures have attracted the attention of researchers in antenna design due to the property of lattice periodicity in space. It is because it can efficiently suppress the surface waves and higher order harmonics. The conventional microstrip antennas have the disadvantages of lower efficiency and narrow bandwidth due to the effect of surface waves [15,16]. PBG structures provide stopbands, which eliminate the propagation of some frequencies, which affects radiation properties of antennas [17][18][19][20][21][22][23][24][25][26][27][28]. Zaidi et al. in [17] have designed a microstrip patch antenna at millimetre wave frequencies using a PBG cover and PBG substrate. They have reported gain improvement from 7.77 dB to 15.52 dB, but their reflection coefficient (S 11 ) has increased significantly from −31.24 dB to −17.26 dB. In [18], a design strategy using a PBG structure on ground plane is used to achieve wider bandwidth for patch antenna. The authors have reported an improvement in the impedance bandwidth from 3.72% to 31.9% at centre frequency 9 GHz after adding PBG on the ground plane. In [19,20], the works reported also show enhancement in gain and bandwidth. The works attempted so far in the literature are either in the low-frequency band or in the upper frequency band. Recently, a new class of antennas using metamaterials has attracted the interest of many researchers. These artificial materials can enhance the characteristics of miniaturized a...