LW Receiver and Antenna Files

(Newest: April 20, 1997)

Some of the material in this area can be viewed as Web pages, and saved as HTML documents. Others are files specifically to be downloaded.

This is one of several library areas under construction. Check for new files regularly.

The Octoloop Antenna. An LF/VLF/ULF receiving loop, inexpensive, suitable for fixed or portable use... "The Octoloop" by Will Payne. (23 Feb 1997)
Loop Antenna Theory. An article by Will Payne, N4YWK, "Sensitivity of Multi Turn Receiving Loops" deals with design considerations for very large receiving loops, useful down to a fraction of a Hertz, for geophysics monitoring. However, the math also has practical applications for antennas at more "normal" frequencies. (22 Feb 1997)
- - Or, you may download a Microsoft Word version of the loop theory document (86 KB).
Universal Preamplifer. A "Universal Antenna Preamplifier" design, in Web page form. Works with long wires, loops, or whips. For longwave and medium wave. (Note about components added 1 Feb 1997)
- - The universal preamp article zipped, in Windows Write form (22 KB).
Remote Loop Tuning. Lyle Koehler's article on remote use of LF loop antennas for receiving purposes, in Web page form.
- - The loop tuning article, zipped, in Windows Write format (9244 bytes).

Upconverter Designs

KF5CQ High Performance Converter uses modern design principles to outperform old-style upconverters. Enables Ham/SWL receivers to cover 25 - 600 kHz with far better sensitivity and noise rejection than their own internal LF coverage, if any. Yet, this design is remarkably easy to build.

Receiver Characteristics and Test Methods

Narrowband Filters for Weak Signals in Noise. John Reed's new article comparing impulse response characteristics of narrow CW filters in DSP and analog receivers. (20 April 1997)

Synchronous Noise Blankers Revisited by John Reed, KA5QEP. For power line related noise, synchronous blanking ahead of a receiver can make a big difference.
Isolating Ground Noise. One major source of noise during LF reception is coupling of interference from the AC mains ground into the antenna system. Isolation of the antenna ground from the power line ground can reduce such noise. The article "Reducing Noise In Home LF Receiving Installations" by James V. Hagan reveals effective techniques for decoupling this noise.