Optical wireless communications in the form of “Li-Fi” is a technical alternative to RF-based Wi-Fi with distinct strengths and weaknesses. Part 1 established a context for Li-Fi. This part looks at basic Li-Fi characters as well as hardware and software structure. Q: What are some of the favorable attributes of Li-Fi? A: There are several, […]
Is Li-Fi “To Be” or “Not To Be”? Part 1: Context
Optical wireless communications in the form of “Li-Fi” is a technical alternative to RF-based Wi-Fi with distinct strengths and weaknesses. You are undoubtedly familiar with Wi-Fi – a contraction of “Wireless Fidelity”– which has become the de facto standard for wireless connectivity between the Internet or local area networks and PCs, smartphones, countless appliances, gadgets, […]
VSWR and impedance, Part 6: Microstrip and stripline
Understanding the role and implications of impedance in RF transmission lines and antennas is vital to successful system performance. The traditional matching approaches are still in wide use, but new application requirements and advances in components, modeling and simulation, and manufacturing precision have also provided new ways to address the matching problem. Q: What is […]
VSWR and impedance, Part 5: Making a match
Understanding the role and implications of impedance in RF transmission lines and antennas is vital to successful system performance. The importance of impedance matching, minimizing reflections, and keeping a low VSWR means these topics have been studied extensively, ranging from analytical perspectives through many physical designs and implementations. This section looks at some matching techniques. […]
VSWR and impedance, Part 4: Measurements
Understanding the role and implications of impedance in RF transmission lines and antennas is vital to successful system performance. The previous section looked at the basics of VSWR. This section looks at two approaches to measuring impedance and VSWR. Q: What do engineers and users need to know? A: For some applications, such as connecting […]
VSWR and impedance, Part 3: Implications
Understanding the role and implications of impedance in RF transmission lines and antennas is vital to successful system performance. The previous sections looked at the basics of impedance and VSWR. This section looks at the implications of VSWR measurements. Q: Why should I care about reflected waves due to impedance mismatch and resultant non-unity VSWR? […]
VSWR and impedance, Part 2: Reflected power
Understanding the role and implications of impedance in RF transmission lines and antennas is vital to successful system performance. Part 1 of this article looked at the basics of impedance matching and power transfer. This part looks at the closely related topic of nominal impedance and VSWR. Q: Why all this worry? Aren’t RF systems […]
The basics of VSWR and impedance, Part 1
Understanding the role and implications of impedance in RF transmission lines and antennas is vital to successful system performance. In any design requiring transfer of an RF signal and its energy from one functional block or component in a system to a subsequent one in the signal chain, there’s almost always the issue of impedance […]
Energy storage by the Farad, Part 3: Hybrid supercapacitors
For operating and backup power and energy storage, engineers can choose among batteries, supercapacitors, or “best of both” hybrid supercapacitors. Just as with rechargeable batteries, supercapacitors need proper management to optimize their performance and avoid mishaps. In many ways, the supervisory requirements for both are similar but there are some differences. Vendors of power-management ICs […]
Energy storage by the Farad, Part 2: Supercapacitors & batteries
For operating and backup power and energy storage, engineers can choose among batteries, supercapacitors, or “best of both” hybrid supercapacitors. The previous part of this article established the context for supercapacitors and explained their structure in simplistic terms; obviously, this is a component with deep physics, chemistry, materials-science considerations, and manufacturing issues. The first widely […]