# Electric-Field-Coupled Resonator Antenna for 5G Applications
###### Abstract  
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 3 GPP 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 \(\mathrm{\SIUnitSymbolOhm}\times\) 0.26 \(\mathrm{\SIUnitSymbolOhm}\times\) 0.017 \(\mathrm{\SIUnitSymbolOhm}\), where \(\mathrm{\SIUnitSymbolOhm}\) 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 1S11 \(<-\)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. LC resonator; capacitive gap; parasitic element; wideband; omnidirectional radiation pattern; compact +
Footnote †: journal: materials  
[PERSON]  
1 Faculty of Engineering, Multimedia University, Persiaran Multimedia, Cyberiaya 63100, Selangor, Malaysia; [EMAIL_ADDRESS]  
[PERSON]  
1 Faculty of Engineering, Multimedia University, Persiaran Multimedia, Cyberiaya 63100, Selangor, Malaysia; [EMAIL_ADDRESS]  
[PERSON]  
1 Faculty of Engineering, Multimedia University, Persiaran Multimedia, Cyberiaya 63100, Selangor, Malaysia; 1181402135@student. the increment of patch area [6]. A fractal antenna with a hexagon-shaped nested loop is proposed which is compact at 1.7 GHz [7]. A low-profile antenna is proposed where the radiating patch is meandered with the use of an open-ended ground slot and shorted pin between the ground plane and the patch [8]. An ultra-miniaturized antenna is designed by creating rectangular slots in the ground and the patch. The antenna shows good bandwidth but very low gain, which limits its applications in wireless communications [9]. In one example of a rectangle-shaped patch with a full ground plane, two U-shaped slots are cut on the patch and a slanted slot is cut on the ground plane to get a compact and wideband antenna. However, for high-frequency portable device applications, it is not compact enough [10]. Two triangle-shaped structures, with triangle-shaped slots cut on both of them, are connected together at the base by a rectangular block to make a patch of a compact antenna, where the bandwidth is reported to be very poor [11]. The other category involves the partial loading of loop resonators (with single or multiple slits) with a particularly shaped resonator to improve the performance or to get a miniaturized structure. Namely, two square-circular split-ring resonator structures are placed in parallel and loaded on the main patch of the antenna. Here, the ring resonators are used to get low-frequency resonance [12]. A penta-ring antenna is presented to get multiband characteristics, which are electrically small at 2.2 GHz, and the impedance bandwidth is 500 MHz of that band [13]. A complimentary split-ring resonator is loaded into a semicircular monopole antenna to achieve multiband operation which is compact at 1.7 GHz [14]. A split-ring resonator and a complementary split-ring resonator are interconnected to a patch to get a multiband property as well as a compact structure. Here, the capacitive gap is responsible for achieving low-frequency resonance [15]. Two split-ring resonator structures are interconnected to a meander line to get a compact structure [16].