In this paper, we propose an eight-port/four-resonator slot antenna array with a dual-polarized function for multiple-input-multiple-output (MIMO) 5G mobile terminals. The design is composed of four dual-polarized square-ring slot radiators fed by pairs of microstrip-line structures. The radiation elements are designed to operate at 3.6 GHz and are located on the corners of the smartphone PCB. The squarering slot radiators provide good dual-polarization characteristic with similar performances in terms of fundamental radiation characteristics. In order to improve the isolation and also reduce the mutual coupling characteristic between the adjunct microstrip-line feeding ports of the dual-polarized radiators, a pair of circular-ring/open-ended parasitic structures is embedded across each square-ring slot radiator. The −10-dB impedance bandwidth of each antenna-element is 3.4-3.8 GHz. However, for −6-dB impedance bandwidth, this value is 600 MHz (3.3-3.9 GHz). The proposed MIMO antenna offers good S-parameters, high-gain radiation patterns, and sufficient total efficiencies, even though it is arranged on a high-loss FR-4 dielectric. The SAR function and the radiation characteristics of the proposed design in the vicinity of user-hand/userhead are studied. A prototype of the proposed smartphone antenna is fabricated, and good measurements are provided. The antenna provides good features with a potential application for use in the 5G mobile terminals. INDEX TERMS 5G, dual-polarized antenna, MIMO system, mobile terminal, ring slot antenna.

A millimeter-wave (mm-Wave) multiple input multiple output (MIMO) antenna operating at 24 GHz (ISM band), suitable for wearable applications, is proposed in this paper. The proposed MIMO antenna consists of two elements, designed with an edge-to-edge distance of 5.14 mm, backed by a 5×5 cell electromagnetic bandgap (EBG) structure. The antenna is fabricated on a flexible Rogers 6002 material (r = 2.94, tanδ = 0.0012, thickness = 0.254 mm). The proposed antenna retains its performance when bent along the x-axis and y-axis. The performance of the antenna in term of s-parameters and radiation properties is studied in free space as well as on a human phantom. Good impedance matching of the antenna at the resonating frequency (24 GHz) is observed when it is bent and when worn on the body. The introduction of the EBG improves the gain by 1.9 dBi, reduces the backward radiation by 8 dB, reduces the power density on the back towards the body from > 200 W/m 2 to < 10 W/m 2 , and also enhances the 10 dB bandwidth by 100 MHz. The antenna possesses a low envelope correlation coefficient (ECC) of 0.24, high diversity gain (DG) of 9.7 dB, reasonable multiplexing efficiency of −0.684 dB and a good peak gain of 6 dBi at 24 GHz. The proposed antenna is suitable for wearable applications at mm-Wave range due to its simple geometry and good performance in bending and on-body worn scenarios.

A printed and minimal size antenna having the functionality of frequency shifting as well as pattern reconfigurability is presented in this work. The antenna proposed in this work consists of three switches. Switch 1 is a lumped switch that controls the operating bands of the antenna. Switch 2 and Switch 3 controls the beam switching of the antenna. When the Switch 1 is ON, the proposed antenna operates at 3.1 GHz and 6.8 GHz, covering the 2.5-4.2 GHz and 6.2-7.4 GHz bands, respectively. When Switch 1 is OFF, the antenna operates only at 3.1 GHz covering the 2.5-4.2 GHz band. The desired beam from the antenna can be obtained by adjusting the ON and OFF states of Switches 2 and 3. Unique beams can be obtained by different combination of ON and OFF states of the Switches 2 and 3. A gain greater than 3.7 dBi is obtained for all four cases.

A low-profile (0.21λ g × 0.35λ g × 0.02λ g ) and a simply-structured frequency-switchable antenna with eight frequency choices is presented in this paper. The radiating structure (monopole) is printed on a 1.6-mm thicker, commercially-available substrate of FR-4 ( r = 4.4, tanδ = 0.020). Specifically, it uses three PIN diodes in the designated places to shift the resonant bands of the antenna. The antenna operates at four different modes depending on the ON and OFF states of the PIN diodes. While in each mode, the antenna covers two unique frequencies (Mode 1 = 1.8 and 3.29 GHz, Mode 2 = 2.23 and 3.9 GHz, Mode 3 = 2.4 and 4.55 GHz, and Mode 4 = 2.78 and 5.54 GHz). The performance results show that the proposed antenna scheme explores significant gain (>1.5 dBi in all modes) and reasonable efficiency (>82% in all modes) for each mode. Using a high-frequency structure simulator (HFSS), the switchable antenna is designed and optimized. The fabricated model along with the PIN diode and biasing network is tested experimentally to validate the simulation results. The proposed antenna may also be combined in compact and heterogeneous radio frequency (RF) front-ends because of its small geometry and efficient utilization of the frequency spectrum.

No abstract

A compact dielectric resonator antenna for ultrawideband vehicular communication applications is proposed. Two cylindrical dielectric resonators are asymmetrically located with respect to the center of an offset rectangular coupling aperture, through which they are fed. Optimizing the design parameters results in an impedance bandwidth of 21%, covering the range from 5.9 to 7.32 GHz in the lower-band and a 53% relative bandwidth from 8.72 to 15 GHz in the upper-band. The maximum achieved gain is 12 dBi. Design details of the proposed antenna and the results of both simulations and experiment are presented and discussed.

A compact four-element multiple-input multiple output (MIMO) antenna is proposed for medical applications operating at a 2.4 GHz ISM band. The proposed MIMO design occupies an overall volume of 26 mm × 26 mm × 0.8 mm. This antenna exhibits a good impedance matching at the operating frequency of the ISM band, whose performance attributes include: isolation around 25 dB, envelope correlation coefficient (ECC) less than 0.02, average channel capacity loss (CCL) less than 0.3 bits/s/Hz and diversity gain (DG) of around 10 dB. The average peak realized gain of the four-element MIMO antenna is 2.4 dBi with more than 77 % radiation efficiency at the frequency of interest (ISM 2.4 GHz). The compact volume and adequate bandwidth, as well as the good achieved gain, make this antenna a strong candidate for bio-medical wearable applications.

A new mixed‐coupled quint‐wideband ASIR bandpass filter with low insertion loss and compact size is proposed: spiral and open‐loop coupled structures realize fundamental mode coupling and enhance another four spurious modes with optimum insertion loss. The fundamental frequency and four spurious frequencies are located at 1.275 GHz with fractional bandwidth (FBW) of 38.4%, 3.225 GHz with FBW of 38.4%, 5.875 GHz with FBW of 12.1%, 7.515 GHz with FBW of 13.7%, 9.74 GHz with FBW of 4.3%. The filter is suitable for multiple applications including GPS, Wi‐Fi and IEEE 802.11a, and partially for IEEE 802.16. The quint‐wideband filter has a performance superior to its currently proposed quint‐wideband counterparts.