A planar, low-profile, dual-band and dual-polarized antenna on a semi-flex substrate is proposed in this paper. The antenna is fabricated on Rogers substrate with a thickness of 3.04 mm and sized at 70.4 × 76.14 × 3.11 mm 3 (0.37λ 0 × 0.40λ 0 × 0.016λ 0 ) only. The circular polarization property is enabled in the global navigation satellite system (GNSS) L1/E1 (lower) band by introducing a complementary split ring resonator on the antenna patch. Meanwhile, the antenna operates in the second (upper) 2.45 GHz WLAN band is enabled by etching a U-shaped slot on its ground plane. This simultaneous, dual-band and dual-polarized operation enables the proposed antenna to be applied in the indoor/outdoor wearable application. To isolate the antenna against the influence of the human body, a multiband artificial magnetic conductor (AMC) plane is added on the reverse side of the dual-band radiator. Comparison of the antenna without AMC in free space and when evaluated on the chest of a human body backed by AMC showed improved gain; from 3-5.1 dBi in the lower band, and from 1.53-5.03 dBi in the upper band. Besides that, the front-to-back ratio of the AMC backed monopole antenna also improved from 11-21.88 dB and from 2.5-24.5 dB in the GNSS and WLAN bands, respectively. Next, the specific absorption rate (SAR) of the monopole antenna with and without the AMC plane is assessed. Evaluation results indicate that the maximum SAR value decreased by up to 89.45 % in comparison with the antenna without AMC in the lower band. This indicates the effectiveness of the AMC array in increasing gain and FBR, besides reducing EM absorption in the human body.INDEX TERMS Wearable antennas, dual-band antennas, dual-polarized antennas, circularly polarized antennas, artificial magnetic conductor (AMC) plane.

A low-cost inkjet printing method for antenna fabrication on a polyethylene terephthalate (PET) substrate is presented in this paper. An office inkjet printer is used to have desired patterns of silver nanoparticle ink on the PET substrate without any postprocessing. Silver nanoparticle ink cures instantly as soon as it is ejected from the printer on a chemically treated PET substrate. The thickness of the silver nanoparticle layer was measured to be 300 nm with a sheet resistance of as low as 0.3 Ω/sq and a conductivity around 1.11 × 10 7 S/m with single layer deposition. A coplanar waveguide-(CPW-) fed Z-shape planar antenna on the PET substrate achieved the measured radiation efficiency of 62% and the IEEE gain of 1.44 dBi at 2.45 GHz. The printed antenna is also tested in bending conditions to ascertain its performance for the Internet of things (IoT) conformal applications for the future 5G network.

A new compact configuration of ultrawideband (UWB) multiple‐input–multiple‐output (MIMO) dielectric resonator antennas (DRAs) with wireless local area network (WLAN) band rejection is proposed. The antenna arrangement consists of two identical inserted rectangular DRAs excited by two microstrip feeds, with an overall compact size of 29 × 29 × 5 mm3. To enhance isolation and improve impedance bandwidth, a stub connected to the ground is added to the bottom plane of the substrate. Further, to reduce interferences with WLAN systems, two L‐shaped parasitic strips connected to the dielectric resonators are added to create a band rejection between 4.98 and 6.08 GHz. The measurement results demonstrate that the proposed DRAs achieve satisfactory MIMO UWB performance, with an impedance bandwidth of around 106% excluding a rejection band for WLAN, low mutual coupling and a low envelope correlation coefficient across the whole desired frequency band.

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