CHEMANDY ELECTRONICS Suppliers of the unusual



High Frequency Active Probe


Radiation Polarisation


Rectangular cross section conductor resistance calculator

Technical Articles

This page contains an index of technical articles and data on our website.

Accurate Method for Measuring Relative Dielectric Constant of a PCB Using a Vector Network Analyser analyzer and parallel plates.
Single page method, condensed from the five page article  below, for those in a hurry. Uses a VNA and has an accompanying calculator.

Building a HF amplifier in a FLEXI-BOX
Five page article, with photographs, showing the construction of a prototype HF amplifier on a PCB and it's assembly into a FLEXI-BOX.

How does an antenna work?
A detailed analysis of the real behaviour of an antenna in a series of articles.
Antenna Current Distribution
Antenna Voltage, Phase, Power and Impedance Distribution
Antenna Near Field Radiation
Elevation of Antenna Radiation
Radiation Polarisation

How does a stub filter work
An analysis of a sine wave signals behaviour in a stub filter.

Linest Function
An explanation of how to use the LINEST function in Excel.

Logest Function
An explanation of how to use the LOGEST function in Excel.

Measuring Characteristic Impedance of PCB tracks using a Vector Network Analyser
Three page article which expands on a method from Transmission Lines and Networks by Walter C. Johnson, McGraw-Hill 1963 p155 Para 4.7 Measurement of the Characteristics of lines. With an accompanying calculator.

Measuring Relative Dielectric Constant using parallel plate method and Vector Network Analyser
A five page article that describes how Chemandy Electronics investigated an accurate parallel plate measurement method using a Vector Network Analyser. With an accompanying calculator.

Preferred Resistor Values
A table of preferred resistor values including E12(10%), E24(5%), E48(2%), E96(1%), E192(0.5%)

RF Trap With Attenuators circuit description
A circuit description of this unique FLEXI-BOX project.

The importance of using calibration standard definitions for a Vector Network Analyser
 An article investigating the need to use standard definitions for a Vector Network Analyser analyzer.

Understanding Coaxial RF Transmission Lines by Measurement and Calculation
A lengthy study of coaxial cables and transmission line theory in simple, logical steps, using a method of measurement and calculation. Hard going and sometimes deviating from classical transmission line theory, this slowly growing article will hopefully shed light on a difficult but intriguing subject.

VHF Pre-amplifier Description
A circuit description of a common base configuration pre-amp that can be used in local or remote powered modes.