Standard filters reflect unwanted stopband energy, but reflectionless filters present a seamless impedance across both stopband and passband which greatly improves performance of the RF signal chain. Filters are an area of intense interest, analysis, simulation, and often physical fabrication along with tests and academic papers. Yet, for hands-on design engineers, it’s important to be […]
What are reflectionless filters, Part 3: basic principles
Standard filters reflect unwanted stopband energy, but reflectionless filters present a seamless impedance across both stopband and passband, which greatly improves performance of the RF signal chain. Beginning in 2011, Dr. Matthew A. Morgan of the National Radio Astronomy Observatory (NRAO) in Charlottesville, West Virginia, working with Tod A. Boyd and later with Wavley M. […]
What are reflectionless filters? Part 2: The need
Standard filters reflect unwanted stopband energy, but reflectionless filters present a seamless impedance across both stop band and pass band which greatly improves performance of the RF signal chain. The higher frequency world of hundreds of megahertz and into gigahertz is very different than the low-frequency world. It is a world where design tools such […]
What are reflectionless filters? Part 1: context
Standard filters reflect unwanted stopband energy, but reflectionless filters present a seamless impedance across both stopband and passband which greatly improves performance of the RF signal chain. Filters are an inherent, inescapable, necessary component in electrical and electronic circuits. Modern systems would be impractical and likely impossible without filters, whether at low frequencies down to […]
Tolerance analysis distinguishes prototypes from production units
It’s not enough to model and simulate circuit behavior – you also have to investigate the effects of component variations from their nominal values due to unavoidable tolerances. There’s a semi-serious quip that scientists can build one of anything – but just one; it takes engineers and production experts to build it again and again […]
Optical links for spacecraft, Part 2: projects and progress
Using laser-sourced light beams rather than wireless RF to link spacecraft with Earth offers the possibility of a significant increase in data rates. Still, there are significant technical challenges to the concept. The previous part of the article established the need for higher-speed data links to spacecraft and their missions, and examined some of the […]
Optical links for spacecraft, Part 1: The throughput limitation
Using laser-sourced light beams rather than wireless RF to link spacecraft with Earth offers the possibility of a significant increase in data rates. Still, there are significant technical challenges to the concept. Scientists, engineers, and researchers communicating with spacecraft have a problem: there’s so much data coming from these spacecraft – and to send to […]
The PC-board atomic clock, Part 3: The CSAC cesium physics cell
Atomic clocks have shrunk from room-sized assemblies down to PC-board mountable modules, admittedly with lower performance than their big siblings but still far better than crystal-based timing alternatives. Every engineer knows that developing a viable design and product is not just a matter of theorizing a design, identifying the constituent components, or building a single […]
The PC-board atomic clock, Part 2: The CSAC design
Atomic clocks have shrunk from room-sized assemblies down to PC-board mountable modules, admittedly with lower performance than their big siblings but still far better than crystal-based timing alternatives. Engineering is largely about tradeoffs and constraints, and atomic clocks are no exception to this situation. As these clocks are being designed into smaller packages through innovations, […]
The PC-board atomic clock, Part 1: Primary and secondary standards
Atomic clocks have shrunk from room-sized assemblies to PC-board mountable modules, admittedly with lower performance than their big siblings but still far better than crystal-based timing alternatives. Atomic clocks are based on the transitions of energy states of specific elements such as cesium, ytterbium, rubidium, and others under specific and tightly controlled conditions. They are […]
