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...

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RF PIN diodes are used to achieve reconfigurability in frequency, polarization, and radiation pattern. The antenna can be used in different bands by controlling ON and OFF states of two PIN diodes using the embedded biasing network (EBN). The antenna can be used for ultra-wideband (UWB) applications (1.0 GHz to 15.2 GHz) with a resonant frequency of 9.2 GHz. Besides ultra-wideband, it can also be switched to other bands (C, X, and Ku) with different operating frequencies (5.75 GHz, 12.3 GHz, and 15.5 GHz) at other biasing combinations. With this type of antenna, Linear and Circular polarization are achievable. The radiation pattern reconfigurable behavior in the vertical plane has also been achieved. Single Design of the proposed antenna is optimized for the multi-band and multi-parameter reconfigurability applications.

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A dual-frequency and radiation pattern reconfigurable microstrip patch antenna for detecting a stationary as well as a non-stationary target is described. Six angular patches, that collectively form a circular shape, are used. All the six patches radiate one by one after a fixed interval of time and their feed controlling is done by six PIN diodes. The switching of PIN diodes is controlled by an embedded biasing network. This antenna provides radiation beam scanning characteristics. It gives the main lobe scanning at every 60o clockwise (or anticlockwise) continuously by applying a signal to patches one by one. The purpose of introducing the slot is to get the radiation pattern in the desired direction since by changing the length, width, and position of the slot, the direction of the radiation pattern can be controlled. The slotted antenna operates in a C band with two frequencies 4.21 GHz and 4.82 GHz and provides a radiation pattern, 90o apart from each other. The scanning rate of 0.6 deg/ms is obtained; however, the scanning rate can be changed with the help of ATMEGA 2560 microcontroller. This compact Microstrip patch antenna can be widely used for short-range applications i.e. ground surveillance radar, missile control, mobile battlefield surveillance for military and many other applications in a modern wireless communication system. The designed antenna along with the switching application will be able to track the stationary as well as a non-stationary target.

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A reconfigurable asymmetric patch antenna with arced corners loaded with a rectangular slot and a T slot on the partial ground used for UWB and Ku band applications. The discussion is carried out into three segments. In the first segment, the design of patch antenna proposed asymmetric arcs at the corner, two side slits, and one slot in the middle of the patch while a T-slot integrated on the partial ground plane. This presented antenna covers an impedance bandwidth ranging from 3.0 GHz to 16.2GHz with a fractional amount of 132%. It is found that a wide band of 3.0 GHz to 10.7 GHz is achieved by using a T-slot on the partial ground plane with a normal rectangular patch while 10.8 GHz to 16.2 GHz is attained by using two corners arcs with two small slits on the patch. The experimental result shows good agreement of 3-dB axial ratio bandwidth and radiation characteristics with the simulated result of the proposed antenna. The second segment proposes an extracted equivalent circuit model for patch and ground plane of corner arc monopole antenna using EM software package in the ADS platform and made a good agreement with the proposed antenna. Finally in the third segment RF PIN diode is embedded in a rectangular slot of the patch which achieves desired frequency shifting in the required band of operation.