|Evaluating Receive Antennas with a Soundcard|
This is a webbly-fied version of the presentation given at the RSGB HF Convention in Manchester on November 2nd. 2003. Originally in one piece , it proved a bit too dense for dial-up digestion, so it is now carved up into several smaller parts. It is suggested that they be read in order, since otherwise one might end up with 'Harry Potter Syndrome', i.e. total mystification upon attempting to read the fifth book without the vital base knowledge in the previous four . . .
Clicking on thumbnail images will bring up larger and hopefully more legible versions.
Section (1) . . Receive Antennas
A brief description of the development and derivation of the popular Terminated Loop ('Ewe-alike') genre of receiving antenna, in particular with details of a loop and an array used as 'targets' for the measuring technique described in Sect. 3.
Section (2) . . Signals, and Signal Processing
An extraordinary and unlikely source of a multitude of predictable test signals. And an introduction to the very powerful software tools that enable their use.
Section (3) . . Measuring
A methodology using the above signals and tools, and some other readily available resources, to plot the azimuth responses of LF and MF receiving antennas with attribution and surprising accuracy.
Section (4) . . Problems and Solutions
Understanding why receive antennas sometimes perform miserably; what can be done about it; using the methods and tools described here to identify, analyse and correct problems.
This presentation has briefly outlined the development of compact terminated loop antennas, detailed a particular arrangement of a single loop, and more particularly a modestly-sized in-line phased array of loops. These two antennas were used as targets for a novel and reasonably accurate azimuth pattern evaluation technique, which relies upon multitudinous broadcast signals and modern PC-based FFT spectral analysis tools to separate and measure them. The technique allows the plotting of antennas' responses, and the ready examination of environmental effects on their behaviour.
Measuring antenna elevation responses will have to wait for the next episode of 'Mission Impossible'.
Here are a few resources for the "Evaluating Lowband Receive Antennas with a Soundcard" presentation. Please see also the 'Kudos and Links' section.