Marcos T. de Melo

2-Bit, 1–4 GHz Reconfigurable Frequency Measurement Device

A reconfigurable frequency measurement (RFM) device operating from 1 to 4 GHz has been designed, simulated, fabricated and tested. The RFM device can identify an unknown signal by assigning it to one of the four sub-bands defined by a switched circuit. The 2-bit design is formed by switching between two branches, where each branch corresponds to one bit. The RFM device is made using PIN diodes and other surface mounted components, integrated on the same dielectric substrate in microstrip technology. Simulated and measured results are shown with a very good agreement.

A diplexer for UMTS applications

In this article a microstrip diplexer is proposed which has good performance on the UMTS upload and download bands, as shown by simulation results and actual measurements. The diplexer is based on a two-pole resonator named H-type resonator, and makes strong use of cross-coupling to pass energy between ports. The fractional bandwidth for both bands is about 3%. The diplexer has an insertion loss of less than 1dB and provides more than 20dB of isolation. A lumped element model for the diplexer is also derived, and its response is shown to be in good agreement to the microstrip diplexer.

A new coplanar interferometer for a 5–6 GHz Instantaneous Frequency Measurement system

Authors have studied a new interferometer based on coplanar strips (CPS) delay-line for application in a 5–6 GHz Instantaneous Frequency Measurement (IFM) system. The interferometer uses two-way Wilkinson power dividers connected to two CPS lines with different signal delays. This interferometer presents smaller dimensions when compared to other designs. A full wave EM simulator is used to obtain the frequency response for device. Simulated responses are presented and compared to theoretical curves.

Plaster glue complex permittivity response in the microwave range

This paper describes a complementary method for determining dielectric properties of granular materials using the Transmission/Reflection Method in order to estimate their moisture content. The Newtons Complex Interactive Method is used here as a numerical tool to calculate the complex permittivity of the plaster glue material. Results for samples with moisture contents of 35%, 40% and 45% in the range of 100 MHz to 3 GHz are presented.

Frequency and angular estimations of detected microwave source using unmanned aerial vehicles

detection of microwave signals in the battlefield or surveillance zone allows identifying enemy outposts, which may include radar or communications transmitters. This paper describes the techniques required to identify the frequency of unknown detected signals and the estimation of their incoming direction using unmanned aerial vehicles.

Design of a complex impedance matching circuit in microstrip used to detect corrosion in anchor rods

Anchor rods have been used to lash down guyed cables in telecommunications and power transmission lines. The ones can be buried or encased in concrete below-ground. Electric power companies perform inspections on their anchor rods through invasive techniques to analyze the corrosion levels. A promising nondestructive technique based on a Frequency Domain Reflectometry (FDR) method has been developed to measure the rods condition. A high frequency connector was designed to plug a network analyzer to the anchor rods. An impedance matching circuit was designed and it must be used between the connector and this instrument. Simulated and experimental results are presented for the matching circuit, and laboratory tests are shown, where it was plugged to the high frequency connector and a one-meter anchor rod.

Localization and diagnosis of stay rod of V guyed towers corrosion

The paper presents an interesting research to a diagnosis system that will can localize and classify the corrosion process in response to electrical signals applied to the rod terminal that emerges from the soil. A special connector was developed to apply and receive high frequency signals on these rods through a network analyzer. Time domain analyses were performed to localize corrosion points on anchor rod surface. The corrosion levels will be inferred by neural network analysis.

Design and construction of a system for detection of lightning discharges on power transmission lines

One of the main concerns of the electric energy generation and distribution operators is the occurrence of atmospheric discharge on the transmission line system. Lightning strikes give rise to transients that can cause damage, affecting the quality of the electric energy and in many cases bringing down the system. This paper describes the conception and experimental results of an electronic system which detects the presence, intensity and location of an atmospheric discharge on a tower or span of a transmission line. A Rogowski coil, simple electronic components, microcontrollers and transceivers build up the proposed system.