In this paper, a wearable antenna array based on a 9 × 3 artificial magnetic conductor (AMC) array is proposed with the characteristics of compact, low profile, low specific absorption rate (SAR), high front-to-back ratio (FBR) and high gain for wireless body area network (WBAN) bands. The proposed wearable antenna consists of a four-element array and an AMC array. The size of antenna array loaded AMC is 137.7 × 45.9 mm2. The dielectric substrate of the antenna and the AMC structure are made of 0.1 mm liquid crystal polymer material, which is flexible and low profiled. The antenna operates from 5.62 to 6 GHz after the AMC structure is loaded. The gain increases by 3.23 dB, reaching 12.03 dB at 5.8 GHz. And the FBR value is raised by 26.04 dB. The highest SAR value of the simulated antenna on the human model is 0.0496 W/kg, far less than the US federal or EU requirements. After constructing and testing the antenna, the outcomes of the tests agreed with the results of the simulation. The flexible antenna array with AMC structure has good prospect in WBAN applications.

In this article, an ultra-wideband printed flexible monopole antenna is proposed for indoor wireless communications. A flexible Rogers RO3003 is used as a substrate, and its performance is estimated for a flat state and when subject to bending along the y-axis. A 2.45 and 5.8 GHz dual-band textile artificial magnetic conductor (AMC) surface consisting of a 4 × 4 unit-cell array was integrated into antenna design with optimum separation distance to extend its potential applications to wearable on-body communications. The specific absorption rate (SAR) levels were numerically investigated using the Hugo human voxel model at both frequencies to evaluate the on-body safety level. Detailed analysis is presented for antenna designs of flat and bent states in free space and on the human body. The proposed UWB flexible antenna has the size of 41 × 38 × 0.25 mm (0.33λ0 × 0.31λ0 × 0.002λ0 at 2.45 GHz). It was added at a distance of 3 mm above a textile AMC surface of 99 × 99 mm. The integrated model is fabricated and experimentally characterized. Measured data and numerical results show that the impedance matching and radiation characteristics are slightly affected by introducing the bending and human body loading. With these remarkable features, the integrated model can be utilized for wireless indoor and wearable applications.

A low profile printed slot antenna (PSA) backed by broadband stacked artificial magnetic conductor (AMC) is introduced in this study. First, a suggested PSA with the radiating tapered slots excited by coplanar-waveguide (CPW) is used to expand the bandwidth in the measured range of 9.05–10.95 GHz (S11 ≤ −10 dB). Then, the suggested stacked AMC surface as the ground plane of the antenna is inserted into the PSA to gain improved radiation efficiency. The realized result from the PSA with the 11 × 17 stacked AMC array exhibits −10 dB measured impedance bandwidth from 6.97 to 13.34 GHz (62.73%). The suggested PSA with AMC compared to the PSA without AMC exhibits a size reduction of 52%, enhanced bandwidth of almost 44%, and excellent impedance matching with uni-directional radiation patterns. The novel AMC unit cell is realized based on the recognized method of stacked elements. The stacked AMC design operates at 10.63 GHz with an AMC bandwidth of 8–12.84 GHz (45.8%) for X-band operation. Besides, by introducing a specific method based on the reflection results of the equivalent waveguide feed, the number of AMC unit cells is investigated to obtain an optimal AMC array. In this approach, an equivalent waveguide feed corresponding to the center operating frequency is considered to choose the number of AMC array reflector.

A wideband staircase pattern defected ground monopole antenna integrated with an artificial magnetic conductor (AMC) reflector has been proposed for C-band (4–8 GHz) and ITU band (8.01–8.5 GHz) applications. The integrated antenna consists of a staircase antenna at top, a 2 × 2 AMC reflector at the bottom and an air substrate as gap between them. The AMC offers 18.5% ± 90° reflection phase bandwidth from 6.10 to 7.32 GHz. The AMC layer has achieved mu-negative properties in the designated band. The AMC proffers polarization independent behavior in the respective frequency band depicting robustness in AMC reflection phase characteristics. The integrated antenna has offered a wide impedance bandwidth of 2.78 GHz (42.8% at 6.5 GHz and 34.1% at 8.15 GHz) due to the defected ground monopole. The integration of wideband AMC beneath the staircase monopole antenna alters the out of phase radiation to in-phase planer pattern which enhances the peak gain up to 9.7 dB. It reduces the 1-g averaged specific absorption rate to 0.223 and 0.324 W/kg at the two designated bands. The structure maintains almost similar bandwidth and gain due to artificial human body loading.

A compact circularly polarized (CP) rectenna with low profile and high efficiency based on the artificial magnetic conductor (AMC) is proposed in this paper. The receiving CP antenna is a coplanar stripline fed dual rhombic loop with an AMC reflector. The proposed AMC reflector not only improves the antenna gain to 9.8 dBi but also decreases the profile to 0.1 λ0. The AMC reflector also makes the antenna have a harmonic suppression function so the low pass filter between the rectifying circuit and the antenna could be omitted and the rectenna has a compact structure. According to the measured results, the rectenna has the highest conversion efficiency of 76% on the load of 240 Ω with the received power of 117.5 mW. When the linearly polarized transmitting antenna is rotated, the conversion efficiency of the CP rectenna maintains a constant high conversion efficiency of 74%. The compact structure and CP operation of the rectenna made it a good candidate of the wireless battery for some electronic devices and far-distance microwave power transmission.

A new Ku-band reflectarray with an artificial anisotropic slab that consists of periodic holes, backed by a planar artificial magnetic conductor (AMC) is proposed. The unit-cell of the reflectarray is a two-layered structure that consists of a dielectric with a hole on a grounded patch. The phase diagram of the proposed unit-cell is calculated by a full-wave computational technique, which uses the dyadic Green's function evaluated by an equivalent transmission line modeling in the spectral domain. The obtained dyadic Green's function is used in an integral equation formulated for the surface current densities on the metallic grating. The resultant integral equation is then solved using the method of moments. The required phase shift at Ku-band is obtained by changing the radius of holes in the artificial slab. The introduced unit cell has linear phase range between 13.95 and 14.95 GHz. It is shown that this frequency band is the usable bandwidth of AMC structure. Finally, the designed reflectarray is analyzed using a full-wave electromagnetic solver. The numerical results show a maximum gain of 27.4 dBi, and 48.09% efficiency, at 14.45 GHz with 4.15% 1-dB gain bandwidth for the designed 21 × 21 cm2 reflectarray.