A minimally-sized, triple-notched band ultra-wideband (UWB) antenna, useful for many applications, is designed, analyzed, and experimentally validated in this paper. A modified maple leaf-shaped main ...radiating element with partial ground is used in the proposed design. An E-shaped resonator, meandered slot, and U-shaped slot are implemented in the proposed design to block the co-existing bands. The E-shaped resonator stops frequencies ranging from 1.8⁻2.3 GHz (Advanced Wireless System (AWS1⁻AWS2) band), while the meandered slot blocks frequencies from 3.2⁻3.8 GHz (WiMAX band). The co-existing band ranging from 5.6⁻6.1 GHz (IEEE 802.11/HIPERLANband) is blocked by utilizing the U-shaped section in the feeding network. The notched bands can be independently controlled over a wide range of frequencies using specific parameters. The proposed antenna is suitable for many applications because of its flat gain, good radiation characteristics at both principal planes, uniform group delay, and non-varying transfer function ( S 21 ) for the entire UWB frequency range.
The purpose of this paper is to analyze the dielectric properties of La
0.7
Sr
0.25
K
0.05
MnO
3
(LSKM) using impedance spectroscopy over the frequency range of 100 Hz to 1 MHz at different ...temperatures from 260 to 380 K. In fact, the dielectric analyses of the sample showed two relaxation processes at different relaxation times related to the effect of microstructural inhomogeneities and the contribution of grain and gain boundaries. However, Ac conductivity behavior reveals a metal–semiconductor phase transition at a specific temperature T
M-S
= 260 K and showed an important impact of the electron–lattice interaction in polaron formation. Also, the conductivity curve is analyzed by Johnscher’s universal power law and the variation of the exponent ‘n’ with temperature suggests the domination of small polaron hopping (SPH) model governed by an activation energy E
a
= 0.12 eV. Further investigations using modulus formalism proved the presence of electrical relaxation, which is in good agreement with impedance results. The dielectric poly-dispersive behavior is related to the conduction process and the large value of the dielectric constant
ε
″
(
ω
)
in the order of 10
6
is correlated to the Maxwell–Wagner relaxation.
This paper presents a wideband, low-profile and semi-flexible antenna for wearable biomedical telemetry applications. The antenna is designed on a semi-flexible material of RT/duroid 5880 (E r = 2.2, ...tanδ = 0.0004) with an overall dimensions of 17 mm × 25 mm × 0.787 mm (0.2λ 0 × 0.29λ 0 × 0.009λ 0 ). A conventional rectangular patch is modified by adding rectangular slots to lower the resonant frequency, and the partial ground plane is modified to enhance the operational bandwidth. The final antenna model operates at 2.4 GHz with a 10-dB bandwidth (fractional bandwidth) of 1380 MHz (59.7 % at the centre frequency of 2.4 GHz). The proposed antenna maintains high gain (2.50 dBi at 2.4 GHz) and efficiency (93 % at 2.4 GHz). It is proved from the simulations and experimental results that the antenna has negligible effects in terms of reflection coefficient, bandwidth, gain, and efficiency when it is bent. Moreover, the antenna is simulated and experimentally tested in proximity of the human body, which shows good performance. The proposed wideband antenna is a promising candidate for compact wearable biomedical devices.
This paper presents a miniaturized circularly polarized multiple-input multiple-output (MIMO) antenna for wearable biotelemetric devices. The proposed MIMO antenna consists of four elements, which ...are placed orthogonally to the adjacent elements. The proposed antenna has a wideband response 10-dB bandwidth of 2210 MHz (fractional bandwidth (FBW) = 92.08%) in free space and 10-dB bandwidth of 2200 MHz (FBW = 91.66%) when worn on human-body, this frequency range covers the important and unlicensed industrial, scientific and medical (ISM) band (2.40-2.48 GHz). The antenna exhibits a wideband 3-dB circularly polarized bandwidth of 1300 MHz (FBW=54.16%) and 1040 MHz (FBW=43.33%) in free space and when worn on the body, respectively. The optimized antenna in free space (on-body) has an envelop correlation coefficient (ECC) less than 0.21 (0.23), a diversity gain (DG) greater than 9.77 dB (9.71 dB), a multiplexing efficiency (ME) greater than -0.85 dB (-0.63 dB), and a channel capacity loss (CCL) less than 0.13 bps/Hz (0.13 bps/Hz). The stable radiation, high gain, high efficiency, and good MIMO properties in free space and on human-body make the proposed antenna a suitable choice for use in high data wearable biotelemetric devices.
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 <inline-formula> <tex-math notation="LaTeX">5\times 5 </tex-math></inline-formula> cell electromagnetic bandgap (EBG) structure. The antenna is fabricated on a flexible Rogers 6002 material (<inline-formula> <tex-math notation="LaTeX">\epsilon _{r}= </tex-math></inline-formula> 2.94 , tan<inline-formula> <tex-math notation="LaTeX">\delta = </tex-math></inline-formula> 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 compact, cylindrical dielectric resonator antenna (CDRA), using radio frequency signals to identify different liquids is proposed in this paper. The proposed CDRA sensor is excited by a rectangular ...slot through a 3-mm-wide microstrip line. The rectangular slot has been used to excite the CDRA for H E M 11 mode at 5.25 GHz. Circuit model values (capacitance, inductance, resistance and transformer ratios) of the proposed CDRA are derived to show the true behaviour of the system. The proposed CDRA acts as a sensor due to the fact that different liquids have different dielectric permittivities and, hence, will be having different resonance frequencies. Two different types of CDRA sensors are designed and experimentally validated with four different liquids (Isopropyl, ethanol, methanol and water).
In this paper, a long-range dual-band rectenna for harvesting ambient radio frequency (RF) energy from GSM/900 and GSM/1800 is presented. Theoretical analysis of the proposed dual-band impedance ...matching network (IMN) is conducted using a modified <inline-formula> <tex-math notation="LaTeX">\Pi </tex-math></inline-formula>-section matching network (MN). The RF-rectifier is integrated with a dual-band inverted-F monopole antenna. The rectenna circuit complexity is minimized by introducing a dual-band IMN, which plays a significant role in improving the harvester RF-to-dc power conversion efficiency (PCE). Measurement results of the proposed design achieved a peak RF-to-dc PCE of 12.93% and 8.0% for an input power of −30 dBm at 0.9 GHz, and 1.8 GHz, respectively. The RF harvester ambiance measurement attained an output dc voltage of 0.374 V. The circuit generates 0.747 V using a low-powered bq25504-674 evaluation module (EVM). Thus, adequate energy management of the proposed rectenna can be used to power many low-powered devices from the harvested ambient RF energy.
This study presents a simple and low‐profile cylindrical dielectric resonator antenna (CDRA) for the fifth‐generation (5G) band (3.5 GHz) with switchable polarization. The antenna can operate with ...linear or circular polarization (right‐handed circular polarization RHCP or left‐handed circular polarization LHCP) by changing the states of the PIN diodes below the CDRA, while keeping the same operating frequencies. The antenna operates at three modes (Mode 1, Mode 2, and Mode 3). It exhibits linear polarization in Mode 1, RHCP in Mode 2, and LHCP in Mode 3. The 10‐dB bandwidths of 750 MHz (3.1–3.85 GHz), 950 MHz (3.03–3.98 GHz), and 960 MHz (3.03–3.99 GHz) are noted for Mode 1, Mode 2, and Mode 3, respectively. The 3‐dB axial ratio bandwidth of 22.2% (3.09–3.86 GHz) and 21.4% (3.08–3.82 GHz) is achieved for Mode 2 and Mode 3, respectively. The reported antenna has high gain ( >5.25 dBi for all operating modes) and high radiation efficiency ( >79.8% for all operating modes). The proposed antenna is suitable for use in polarization diversity applications.
Abstract
This paper described a four-band implantable RF rectifier with simplified circuit complexity. Each RF-rectifier cell is sequentially matched to the four operational frequencies to accomplish ...the proposed design. The proposed RF rectifier can harvest RF signals at 1.830, 2.100, and white space Wi-Fi bands between 2.38 to 2.68 GHz, respectively. At 2.100 GHz, the proposed RF harvester achieved a maximum (radio frequency direct current) RF-to-DC power conversion efficiency (PCE) of 73.00% and an output DC voltage
$$V_{DC}$$
V
DC
of 1.61 V for an RF power of 2 dBm. The outdoor performance of the rectenna shows a
$$V_{DC}$$
V
DC
of 0.440 V and drives a low-power bq25504-674 evaluation module (EVM) at 1.362 V. The dimension of the RF-rectifier on the FR-4 PCB board is 0.27
$$\lambda _{g}$$
λ
g
$$\times$$
×
0.29
$$\lambda _{g}$$
λ
g
. The RF-rectifier demonstrates the capacity to effectively utilize the frequency domain by employing multi-band operation and exhibiting a good impedance bandwidth through a sequential matching technique. Thus, by effectively controlling the rectenna’s ambient performance, the proposed design holds the potential for powering a range of low-power biomedical implantable devices. (BIDs).
LiDAR is a technology that uses lasers to measure the position of elements. Measuring the laser travel time and calculating the distance between the LiDAR and the surface requires the calculation of ...eigenvalues and eigenvectors of the convergence matrix. SVD algorithms have been proposed to solve an eigenvalue problem, which is computationally expensive. As embedded systems are resource-constrained hardware, optimized algorithms are needed. This is the subject of our paper. The first part of this paper presents the methodology and the internal architectures of the MUSIC processor using the Cyclic Jacobi method. The second part presents the results obtained at each step of the FPGA processing, such as the complex covariance matrix, the unitary and inverse transformation, and the value and vector decomposition. We compare them to their equivalents in the literature. Finally, simulations are performed to select the way that guarantees the best performance in terms of speed, accuracy and power consumption.
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