In this paper, a defected ground-structured antenna with a stub-slot configuration is proposed for future 5G wireless applications. A simple stub-slot configuration is used in the patch antenna to get the dual band frequency response in the 5G mid-band and the upper unlicensed frequency region. Further, a 2-D double period Electronic band gap (EBG) structure has been implemented as a defect in the metallic ground plane to get a wider impedance bandwidth. The size of the slots and their positions are optimized to get a considerably high impedance bandwidth of 12.49% and 4.49% at a passband frequency of 3.532 GHz and 6.835 GHz, respectively. The simulated and measured realized gain and reflection coefficients are in good agreement for both operating bandwidths. The overall antenna structure size is 33.5 mm × 33.5 mm. The antenna is fabricated and compared with experimental results. The proposed antenna shows a stable radiation pattern and high realized gain with wide impedance bandwidth using the EBG structure, which are necessary for the requirements of IoT applications offered by 5G technology.

In this paper, a unit cell of a single-negative metamaterial structure loaded with a meander line and defected ground structure (DGS) is investigated as the principle radiating element of an antenna. The unit cell antenna causes even or odd mode resonances similar to the unit cell structure depending on the orientation of the microstrip feed used to excite the unit cell. However, the orientation which gives low-frequency resonance is considered here. The unit cell antenna is then loaded with a meander line which is parallel to the split bearing side and connects the other two sides orthogonal to the split bearing side. This modified structure excites another mode of resonance at high frequency when a meander line defect is loaded on the metallic ground plane. Specific parameters of the meander line structure, the DGS shape, and the unit cell are optimized to place these two resonances at different frequencies with proper frequency intervals to enhance the bandwidth. Finally, the feed is placed in an offset position for better impedance matching without affecting the bandwidth The compact dimension of the antenna is 0.25 λL × 0.23 λL × 0.02 λL, where λL is the free space wavelength with respect to the center frequency of the impedance bandwidth. The proposed antenna is fabricated and measured. Experimental results reveal that the modified design gives monopole like radiation patterns which achieves a fractional operating bandwidth of 26.6%, from 3.26 to 4.26 GHz for |S11|

This paper proposes a novel matching network with a DGS structure to enhance the bandwidth of a two-element array antenna. The array antenna only generates a single resonance with a conventional partial ground plane with poor bandwidth and gain. Several dips are observed when the matching network is loaded between the array elements, but their matching is not good enough. Then, the partial ground is applied with a DGS structure, which improves the low-frequency band’s matching. After that, three rectangular parasitic blocks are placed on the ground plane to improve the matching of the high-frequency band. Parametric analysis is done on several parameters to position these two bands close enough, considerably enhancing the bandwidth. The overall dimension of the proposed antenna is 30 mm ×30 mm ×1.6 mm. A prototype of the proposed antenna is fabricated and measured. Experimental results show that the antenna has an operating bandwidth of 70% for |S11| < −10 dB ranging from 3.05 GHz to 6.32 GHz, where a pick gain of 3.07 dBi is realized. The radiation patterns at the two significant dips are stable. The cross-polarization level in the E plan is less than − 16 dB at the low resonant frequency.

In this paper, a compact wideband patch antenna comprising a modified electric-field-coupled resonator with parasitic elements is presented. The resonance at low frequency is achieved due to the electric field polarization along the split of the conventional LC (inductive-capacitive) structure. However, this antenna gives low bandwidth as well as low gain. Some evolutionary techniques are adopted to get a compact wideband antenna at 3GPP bands of 5G. The split width and the ground plane are modified to achieve enhanced bandwidth with good impedance matching, whereas the addition of the parasitic elements on both sides of the microstrip feed line enhances the gain with a slight reduction of bandwidth. The compact dimension of the proposed antenna is 0.26 λ_L × 0.26 λ_L × 0.017 λ_L, where λ_L is the free space wavelength at the lowest frequency. A prototype of the presented design is fabricated and measured. Measurement shows that the antenna has an operating bandwidth of 19.74% for |S11| < −10 dB where the gain of 1.15 dBi is realized. In addition, the radiation pattern is omnidirectional in the horizontal plane and dumbbell shaped in the elevation plane. The cross-polarization levels in both planes are less than −12 dB.

This paper presents the design analysis of a dual negative metamaterial inspired antenna loaded with LC resonator for 5G wireless application. The structure of the proposed metamaterial unit cell is similar to an electric field coupled LC-resonator except that a parallel inductive strip is connected to it. This resulted final design gives the negative value of permittivity and permeability with a durable negative index which improves the performance of the antenna. The proposed metamaterial antenna is designed on a FR4 substrate with a thickness of 1.575 mm and a dielectric constant of 4.3. The electrical dimensions of this antenna are 0.32 λ 0.33 λ at a low frequency of 3.43 GHz. The resulted antenna gives a dual band property with a -10dB impedance bandwidth of 12.196% and 26.935% covering the bandwidth of 3.434 GHz to 3.88 GHz and from 5.59 GHz to 7.33 GHz respectively. The realized gains at the two resonant frequencies are 2.1 dB and 3.98 dB. The improvement of the antenna performance after connecting the inductive strip parallel to the LC resonator reveals the fact that this type of modification can increase the performance of patch antenna.