Design of ultra-compact ISM band implantable patch antenna for bio-medical applications

In this paper, an ultra-compact implantable antenna for biomedical applications is proposed. The proposed implanted meandered compact patch antenna is implanted inside the body at a depth of 2 mm. The proposed antenna was designed with Roger RO3003 (ɛr = 3) as substrate with an overall size of dimensions 5 × 5 × 0.26 mm3. The radiating element is a square patch antenna with different size rectangular slots and coaxial feeding. The proposed implantable antenna resonates at 2.45 GHz (from 2.26 to 2.72 GHz) frequency with a bandwidth of 460 MHz and a gain of −22.6 dB. The specific absorption rate has been considered for health care considerations, and the result is within the limits of the federal communication commission. The measured and simulated scattering parameters are compared, and good agreements are achieved. The proposed antenna is simulated and investigated for biomedical applications suitability.

Microwave scattering parameters of ferro-nano-carbon–composites for tracking range countermeasures

Ditching radar seekers at a microwave tracking range is of utmost tactical importance which could be realized by developing insight into designing an effective electromagnetic interference (EMI) shield. We report...

Phase Role in the Non-Uniformity of Main-Line Couplings in Asymmetric Extracted-Pole Inline Filters

The use of classical symmetrical polynomial definition to synthesize fully canonical inline filters with an asymmetrical distribution of the transmission zeros along the topology leads to the occurrence of uneven admittance inverter in the main-line. This form introduces some limitations to transform such topology into a ladder network. Despite circuital transformation can be used to accommodate both technology and topology, it is usual that extra reactive elements are necessary to implement phase shifts required to achieve the complete synthesis. This article introduces a novel method able to determine the required phase correction that has to be applied to the characteristic polynomials in order to equalize all the admittance inverters in the main path to the same value. It has been demonstrated that a suitable pair of phase values can be accurately estimated using a developed hyperbolic model which can be obtained from the transmission and reflection scattering parameters. To experimentally validate the proposed method, a Ladder-type filter with asymmetrical polynomial definition has been synthesized, fabricated, and measured, demonstrating the effectiveness of the developed solution.

Vector Analysis of Electrical Networks for Temperature Measurement of MOS Power Transistors

The article presents the concept of using VNA (Vector Network Analyzer) to measure the temperature of the MOS transistor junction. The method assumes that the scattering parameters of the network consisting of the transistor depend on the temperature. The tests confirmed the influence of temperature on the S11 parameter and the input network capacity during ambient temperature changes in the range of 35–70 °C. Measurements were made for the gate-source (G-S) input of the system. The measurements were carried-out with the transistor in the ON/OFF states. In order to validate the measurements, the temperature of the tested element was recorded with the MWIR Cedip-Titanium thermal imaging camera.

Time-Domain Pulse Waveform Correction for Pulsed Electric Field Measurement in Microwave Cable with Frequency-Dependent Loss

This paper presents a method that corrects pulse waveforms distorted by the frequency-dependent loss of microwave cables in measuring pulsed electric fields (PEFs). Because the distortion resulting from the microwave cable disrupts accurate PEF measurements, the distorted pulse should be corrected for precise PEF effect testing. The proposed correction method is achieved by a transfer function that is determined by ABCD parameters calculated from the scattering parameters of the cable. A 10-m microwave cable is tested to validate the proposed method, where the input pulse is a 2-ns sine pulse of a single cycle. Here, the output pulse, scattering parameters, and cable resistance are measured. These measurement results are used to represent the transfer function in MATLAB for the proposed correction method. The test results show that the corrected pulse obtained from the transfer function has an error of 4.5% in the peak-to-peak voltage and an error of 0.8% in the bipolar pulse width compared to the reference input pulse. The errors of PEF measurement decrease dramatically by using the proposed correction method. Moreover, the correction method is validated for various pulse durations, pulse shapes, and cable types.

Material Thickness Classification Using Scattering Parameters, Dielectric Constants, and Machine Learning

Wall-thinning in building structures due to corrosion and surface erosion occurs due to the severe operating conditions and the changing of the surrounding environment, or it can result from poor workmanship and a lack of systematic monitoring during construction. Hence, the continuous monitoring of structures plays an important role in decreasing unexpected accidents. In this paper, a novel method based on the deep neural network and support vector machine approaches is investigated to build up a thickness classification model by incorporating different input features, including the dielectric constants of the material under test, which are extracted from the scattering parameters proceeded by the National Institute of Standards and Technology iterative method. The attained classification results from both machine learning algorithms are then compared and show that both of the models have a good prediction ability. While the deep neural network is the better solution with a large amount of data, the support vector machine is the more appropriate solution when employing small dataset. It can be stated that the proposed method is able to support systematic monitoring as it can help to improve the accuracy of the prediction of material thickness.