Some recent articles discussed some effects that in part are a result of Zo having a complex value (ie a non-zero imaginary part). Continue reading On working with complex Zo
I purchased some ESP01S ESP8266 based WiFi modules on eBay.
Above, the ESP01S is a basic module comprising an ESP8266 and 1MB SPI flash memory (~$2.50 on eBay). Continue reading ESP01S first experience
The article On negative VSWR – Return Loss implications raised the question of the validity of the concept of that P=Pfwd-Prev.
The Superposition Theorem is an important tool in linear circuit analysis, and is used to find the combined response of independent sources. Superposition applies to voltages and currents, but not power. Continue reading On the concept of that P=Pfwd-Prev
On negative VSWR (read it first) discussed the case of negative VSWR results from some calculating tools and formulas, and more generally that simple formulas that depend on lossless line assumptions produce errors on practical lossy line scenarios.
Return Loss is defined as the ratio Pfwd/Prev, often given in dB.
Return Loss is usually calculated as 20*log(1/ρ), it yields negative calculated Return Loss for ρ>1. It would be a mistake to doctor the result to hide the negative return loss as it is a strong hint that the results may be invalid.
An important consideration here is the validity of the concept of Pfwd and Prev. Continue reading On negative VSWR – Return Loss implications