In this episode Shahriar demos various microwave and mm-wave connectors, components and modules. The purpose of this video is to help new engineers become familiarized with microwave components and help reduce the chance of component damage and failure.
This video demonstrates microwave connectors (BNC, SMA, 3.5mm, 2.92mm (K), 2.4mm, 1.85mm (V), 1.0mm), interfacing instructions, attenuators, power splitters (both resistive and reactive), phase shifters, mm-wave cables, AC coupling caps, Bias-Ts and their principle of operation, mixers, tuning stubs, couplers, switched attenuators, microwave filters, multipliers, amplifiers, coaxial to waveguide converters, waveguide components including horn antennas, and directional couplers. The video also demonstrates Cascade GSG probes and GGB custom composite RF probes. The documents for this video can be downloaded from here.
In this episode Shahriar repairs an Agilent E4421A synthesized signal generator purchased from eBay. The unit displays the error messages “UNLOCK” and “UNLEVEL”. The cause of failure is investigated and traced. Alongside the repair efforts, the internal construction and components of the synthesizer are also presented. A short tutorial on the advantages and disadvantages of using a Darlington transistor is also presented as well as the schematic of a simple Darlington based voltage regulator. The documents for this tutorial can be found here.
In this episode Shahriar demonstrates the functionality and applications of an Agilent 11896A Polarization Controller. Various fiber optic communication methods are presented. This includes the use of complex modulation schemes (such as PAM and QAM for coherent receivers), polarization division multiplexing (PDM), wavelength division multiplexing (WDM), and spatial division multiplexing (SDM). The concept of light polarization is demonstrated by using a pair lenses from a consumer theater 3D glasses and two blue LEDs with uncorrelated lighting patterns.
In order to test the polarization controller, a solid-state laser source, SMF fiber with APC/PC connectors as well as a polarization beam splitter is presented. By using a pair of optical power sensors, the functionality of the polarization controller is verified. Finally, the teardown of the unit is presented and the method to achieve polarization control is observed.
The fiber optic communication overview document can be downloaded here. I’d also like to acknowledge my colleague and friend Dr. Timo Pfau for his expertise and consult on fiber optic communication methods.
In this episode Shahriar continues his investigation of discrete Bipolar amplifier design. The advantages and disadvantages of Class-A amplifiers are explained. The conceptual schematic of a Class-B amplifier is presented which leads to the introduction of Class-AB amplifier circuit to overcome the ‘dead-zone’ impairment of a push-pull Class-B design. To further improve the Class-AB amplifier and lower its input impedance, a final Class-A followed by Class-AB amplifier is presented The component parameters are calculated and the schematics is explained in detail. All circuits are then implemented on a breadboard and tested both in the time domain and frequency domain. All schematics can be downloaded from here.
In this episode Shahriar demonstrates one of the simplest magnetic levitation circuits. First, the basic concept of magnetic levitation is examined. Two different methods of detecting the location of the levitating object is presented and the Hall effect sensor method is chosen. A semi-digital overall system is implemented where a PWM control IC is employed to control the magnetic field strength. The block diagram and functionality of this IC is presented. Finally, the schematic of a dual-Hall effect sensor solution is presented. The circuit is built and tested in both open-loop and close-loop configuration. Magnetic levitation is demonstrated with the capability of adjusting the levitation location. The schematic of circuit can be downloaded here and the electromagnet can be purchased from here.
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