Calculation of impedance of a ferrite toroidal inductor – from first principles

A toroidal inductor is a resonator, though it can be approximated as a simple inductor at frequences well below its self resonant frequency (SRF). Lets take a simple example, a ferrite toroid of rectangular cross section. From the basic definition we can derive the relationship that the flux density in the core with current I … Continue reading Calculation of impedance of a ferrite toroidal inductor – from first principles

nanoVNA-H – measure ferrite transformer

This article demonstrates the use of the (modified) nanoVNA-H to measure Loss (Transmission Loss) and Insertion Loss of a small ferrite 64:1 RF transformer, and the Insertion VSWR and Return Loss. The transformer was designed for a receive application at 9MHz. Firstly let’s define the meaning of the terms: Last update: 2nd February, 2020, 7:11 … Continue reading nanoVNA-H – measure ferrite transformer

nanoVNA-H – measure ferrite core permeability

This article demonstrates the use of the (modified) nanoVNA-H to capture data from which the complex relative permeability of an unknown ferrite core is calculated and plotted Above, a single turn of wire through the sleeve allows measurement by the nanovna. The nanoVNA fundamentally captures s11 parameters which we need to convert to relative permeability. … Continue reading nanoVNA-H – measure ferrite core permeability

nanoVNA-H – a ferrite cored test inductor impedance measurement – s21 series vs s11 reflection

One often sees experts online insisting that s11 reflection impedance measurements of common mode chokes is inaccurate, and the ONLY way is s21 series measurement. This one is built upside down so the connections are visible. In this experiment using the SDR-KITS VNWA testboard (above), a series of measurements are made of an inductor, and … Continue reading nanoVNA-H – a ferrite cored test inductor impedance measurement – s21 series vs s11 reflection

nanoVNA-H – a ferrite cored test inductor – drilling down on a glitch – the fix

The NanoVNA is a new low cost community developed VNA with assembled units coming out of China for <$50. This article documents some tests using a small ferrite cored test inductor that provides a similar impedance to that of a common mode choke suited to HF antenna feed lines. The nanoVNA-H has firmware NanoVNA-Q-0.4.3-20f33ba.dfu installed. … Continue reading nanoVNA-H – a ferrite cored test inductor – drilling down on a glitch – the fix

nanoVNA-H – a ferrite cored test inductor – drilling down on a glitch

The NanoVNA is a new low cost community developed VNA with assembled units coming out of China for <$50. I have been evaluating one for common tasks around a ham station and noticed a persistent glitch around 7.5MHz in scenarios where |s21| is high. The nanoVNA-H has firmware NanoVNA-Q-0.4.3-20f33ba.dfu installed. The nanoVNA appears to be … Continue reading nanoVNA-H – a ferrite cored test inductor – drilling down on a glitch

nanoVNA-H – a ferrite cored test inductor

The NanoVNA is a new low cost community developed VNA with assembled units coming out of China for <$50. This article documents some tests using a small ferrite cored test inductor that provides a similar impedance to that of a common mode choke suited to HF antenna feed lines. The nanoVNA-H has firmware NanoVNA-H_20191018.dfu installed. … Continue reading nanoVNA-H – a ferrite cored test inductor

Online calculator of ferrite material permeability interpolations – more detail

The Ferrite permeability interpolations calculator performs interpolations of tables of complex permeability data. From manufacturer’s curves Some of the data is derived from manufacturer’s published complex permeability curves. The plot above shows the Ferroxcube’s published curve for 3C81 material, and points at which it was digitised to extract a table of µ’ and µ”. Last … Continue reading Online calculator of ferrite material permeability interpolations – more detail