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This paper presents two flexible monopole antennas implemented on cotton substrate as sensors designed for radar-based microwave imaging and particularly breast imaging systems. The flexible antennas are basic building block of a radar-based microwave imaging system that could be integrated in clothes. Thus, these low-cost textile sensors could be used by women for self-monitoring and early breast cancer detection at an affordable price. The ultra-wideband fully textile sensors are designed as rectangular and circular monopole antennas. Both sensors have an impedance bandwidth $$\le $$ ≤ − 10 dB from 2.2 to 8 GHz with an overall footprint of 50 × 50 mm2. Simulations for antenna in proximity to breast model with and without tumor as well as bending capacity are performed. The simulations are complemented with fabrication of a breast phantom and a tumor sample with parameters that mimic these of the human breast’s healthy and malignant tissue. Measurements are compared to simulation results as well as the performance of antenna before and after subjected to washing. Finally, the specific absorption rate is also calculated and measured to ensure safety for on-body deployment. The proposed work demonstrates the potential to develop wearable microwave imaging system using fully textile antennas.

This paper presents an ultra-wideband (UWB) fully textile sensor for Breast Cancer Detection (BCD). The sensor is made of a monopole antenna implemented on cotton substrate with thickness 2 mm and conducting fabric for the radiating element and the ground. The antenna operates at impedance bandwidth < −10dB in the band of 2 to 6 GHz with an overall footprint of 50 × 50 mm2. Measurements highly match simulation results. Moreover, performance of antenna before and after subjected to washing is measured and compared. Simulations of antenna in proximity to breast model with and without tumor are also conducted. Finally the specific absorption rate (SAR) is also calculated to insure that the developed textile sensor is safe to be deployed on-body. The proposed work demonstrates the potential to develop wearable microwave imaging system using fully textile antennas.

This paper presents a novel, low cost flexible paper substrate suitable for biosensing applications. A microstrip patch antenna consisting of copper tape foil and a cellulose filter paper as a substrate with thickness of 180 μm is fabricated and tested. The substrate has measured dielectric constant (e r ) of 1.9 and losses (tan δ ) of 0.025. For 3.8 GHz resonance, the antenna has size of 29.5 mm x 38 mm on a ground plane of 50 mm x 60 mm. Measurements of the final design are in excellent agreement with simulations. Moreover, measurements of the patch antenna on the proposed substrate (cellulose filter paper) collected at different bending radii and folding angles demonstrate performance consistency.

This paper introduces design, fabrication and measurements for a printed meander dipole antenna with enhanced -10 dB bandwidth of 20 MHz (13%) in the VHF band. The antenna is fabricated on FR4 substrate with an overall compact area of 61.3 cm X 6.45 cm. The dipole antenna is composed of meander line terminated with a stub. Bandwidth enhancement is realized through two techniques; 1) resistive loading to the meander line, and 2) metal strips at the back side acting as capacitive loading. A parametric study is implemented for the position, values of the resistors and the dimensions of the metal strips to realize maximum bandwidth. Using resistive loading, the bandwidth is increased from 6.6 MHz to 12 MHz with efficiency 42 %. On the other hand, adding two metal strips further increases the bandwidth to 20 MHz with efficiency up to 56%. The antenna exhibits omnidirectional radiation characteristics over the operating frequency band 140-160 MHz. The proposed structure is fabricated, measured and compared to simulated results, where measurements are in good agreement with simulation results.

This paper introduces printed Meander dipole antenna with dual bands operating at 73 MHz and 145.75 MHz for low frequency and Ground Penetrating Radar (GPR) applications. The antenna is implemented on FR4 substrate with an overall size of 61.3 X6.45 cm2 (0.15λo x 0.015λo). A 70% reduction in length is realized with the proposed antenna design compared to a regular dipole operating at the lower band. The reflection coefficient for the measured antenna is -15 dB and -18.5 dB at 73 MHz and 145.75 MHz with bandwidth of 2 MHz and 6.6 MHz, respectively. The antenna exhibits omnidirectional radiation characteristics at both bands with radiation efficiency up to 87%. The proposed structure is fabricated, measured and compared to simulated results. Measurements are in good agreement with simulation results. Moreover, measurements and simulations for antenna in proximity to soil as well as with buried objects are also presented.

Analysis of sweat is of interest for a variety of diagnosis and monitoring applications in healthcare. In this work, detailed measurements of the dielectric properties of solutions representing the major components of sweat are presented. The measurements include aqueous solutions of sodium chloride (NaCl), potassium chloride (KCl), urea, and lactic acid, as well as their mixtures. Moreover, mixtures of NaCl, KCl, urea, and lactic acid, mimicking artificial sweat at different hydration states, are characterized, and the data are fitted to a Cole&ndash, Cole model. The complex dielectric permittivity for all prepared solutions and mixtures is studied in the range of 1&ndash, 20 GHz, at temperature of 23 &deg, C, with ionic concentrations in the range of 0.01&ndash, 1.7 mol/L.

Optical coherence domain polarimetry (OCDP) utilizes incoherent light and is based on Michelson interferometer. This paper presents a polarization maintaining (PM) Michelson fiber interferometer utilizing a single PM fiber loop mirror (Sagnac Loop) that replaces the conventional free space mirrors for OCDP systems. This implementation is environmentally robust and alleviates much of the mechanical complications necessary to reduce temperature and vibrations effects. A piezoelectric transducer (PZT) is inserted in one of the arms of the interferometer and driven near its resonance. This enables a detailed measurement of polarization coupling around any point in the device under test. An analytical model is given, based on Pauli matrices algebra, that includes the side effects due to component imperfections. It is shown that the polarization coupling in the PZT has the largest side effect on the OCDP output. Experimental investigations verify the accuracy of the theoretical model. Measurements are done on two PM PANDA fibers of lengths 20 and 150 m, respectively. In addition, the new system successfully measures distributed polarization mode coupling, group birefringence, and group birefringence dispersion for the fiber under test.

This paper presents a feasibility study for a non-wearable, conformal, low cost, and disposable antenna-based sensor for non-invasive hydration monitoring using sweat. It is composed of a patch antenna implemented on a cellulose filter paper substrate and operating in the range 2&ndash, 4 GHz. The paper substrate can absorb liquids, such as sweat on the skin, through two slots incorporated within the antenna structure. Thus, the substrate dielectric properties are altered according to the properties of the absorbed liquid. Changes in reflection-based measurements are used to analyze salt solutions and artificial sweat, specifically the amount of sampled solution and the sodium chloride (NaCl) concentration. Using the shift in resonant frequency and magnitude of the reflection coefficient, NaCl concentrations in the range of 8.5&ndash, 200 mmol/L, representing different hydration states, are detected. The measurements demonstrate the feasibility of using microwave based measurements for hydration monitoring using sweat.

In this paper a new 140 MHz miniaturized monopole antenna is introduced. This antenna is suitable for several low frequency electromagnetic surveying systems. The design is based on Meander Line with overall foot print of 29.3 cm x 6.45 cm. It acquires length reduction of 46% compared to traditional monopole operating at 140MHz. It also introduces 13 MHz enhanced bandwidth. The proposed design also exhibits omnidirectional characteristics with radiation efficiency of 80.2% and directivity of 1.68 dBi. The proposed configuration has been fabricated and measured, where sub 200 MHz operation is confirmed from both simulation and measurements.

We present an all-fiber design for a single polarization Yb-doped fiber laser with all-fiber connections spliced. Single polarization with a high extinction ratio was achieved by the design of a laser cavity consisting of a fiber Bragg grating inscribed on a single-polarization fiber as a high reflective mirror and a piece of end-cleaved single-polarization fiber as an output coupler. The fiber laser operates at 1063.25 nm with an output power of 1.7 W, an optical signal- to-noise ratio of 70 dB and a narrow bandwidth of 54 pm. The laser output has a polarization extinction ratio of 700:1 or 28 dB, and a very stable power output.

This paper presents mathematical model and analysis of multi-variable optimization problem for Q-switched double clad fiber lasers. In the proposed optimization problem, both cases for maximizing output pulse energy and power functions are studied. For the energy function case, the optimum value for variable, z, tends to go to infinity which revels linear increase of energy function with z. However for the power function, two possible optimal solution of z from the two-variable optimization problem are forced to be one solution when multi-variable problem is considered. Analytical analysis and normalized fiber length curves are presented and compared for different optimization cases.

This paper presents a novel design for the implementation of a patch antenna over a high impedance wire (HIW). The proposed configuration enhances the efficiency of the patch antenna to 98% together with size reduction of 75%. The performance of the patch antenna over HIW has been analyzed using both electromagnetic and circuit models. Simulated investigations have been verified by fabrication and measurements at 3.2 GHz.

A wideband fractal slot antenna is proposed. The design is based on the Sierpinski and Parany antennas. The configurations of the conductors and non-conductors have been exchanged, producing Sierpinski and Parany slot antenna configurations. In addition, to increase the bandwidth of the proposed Sierpinski slot antenna, several triangular slots have been etched symmetrically into the triangular conductors. The proposed modified Parany slot antenna provides bandwidth from 3.8 to 10.5 GHz for VSWR

A circularly polarized fractal slot antenna is proposed in this paper. The design is based on the Sierpinski shape. The conductors and nonconductors configurations have been exchanged to produce a Sierpinski slot antenna configuration. Then, four versions of the developed Sierpinski slot antenna are placed at right angles to each other to form a symmetrical structure in the form of square. In addition, by introducing an asymmetry in the proposed slot antenna, which is implemented by extending the ground into the square antenna, circular polarization is achieved. The proposed slot antenna has a 3 dB axial ratio bandwidth of 28% (8.6 to 11.4 GHz) with VSWR < 2. The antenna has a maximum gain of 5 dB, radiation efficiency of 97%, and a compact size of 2/spl times/2 cm/sup 2/. The analysis and design of the proposed antenna have been performed using the full-wave electromagnetic simulator HFSS/spl reg/. The proposed antenna has been fabricated and measured, where good agreement between simulated and measured results is observed.

An ytterbium-doped mode-locked fiber laser was demonstrated with a chirped fiber Bragg grating for dispersion management. The cavity net dispersion could be changed from large normal dispersion (2.4 ps(2)) to large anomalous dispersion (-2.0 ps(2)), depending on the direction of the chirped Bragg grating in laser cavity. The proposed fiber lasers with large normal dispersion generated stable pulses with a pulse width of

We demonstrate a dual-wavelength linearly polarized all-fiber laser emitting 1- μm and 1.5- μm wavelengths with a total output power of 1.3 W. The laser consists of two pairs of fiber Bragg gratings (FBGs) fabricated on PM fibers to form a cavity and an Er/Yb co-doped fiber as a gain medium. A high extinction ratio of 23 dB is achieved using specially designed PM FBGs. The laser output has a narrow bandwidth of 26 pm at both 1057 and 1554 nm. When the dual-wavelength all-fiber laser is used to pump a PPLN crystal, the generation of mid-infrared emission at 3.3 μm is successfully demonstrated.