Historical article:

A summary of a lecture delivered to the Wireless Institute of Australia
on June 15, 1939, this article will be welcomed by all who are interested
in fading and skip-distance transmission on various frequencies.

By R. H. Healy, D.Sc., E. inst. P.

1. INTRODUCTION

SHORT-WAVE circuits operating between wave-lengths of 10 and 100m. (30 and 3 mcs.) are dependent, in the majority of cases, on reflections from the ionised regions or layers of the atmosphere. In the absence of these reflections, communications by means of the ground ray alone is only possible up to comparatively short distances, the actual distance depending on such factors as the earth resistivity, the wave-length, and the height of the transmitter and receiver above earth.

 Historical article:

STARS CONTROL WAVE-LENGTH;

USED TO CHECK TUNING FORK

An interesting development in checking the frequencies of broadcasting stations is announced by the A.W.A. Research Laboratory

THE stars in the heavens have been harnessed to prevent overlapping among broadcasting stations. By their aid, complaints of interference between any of the 121 stations in Australia have been practically eliminated.

To test whether a station is on its wave-length, the scientific staff at the A.W.A. Research Laboratory, Ashfield, employs a tuning fork of high-grade Elinvar steel. This fork, when vibrating, has a natural frequency of 1000 cycles per second, and when its frequency is compared with the frequency of a broadcast station or control equipment in course of manufacture, the slightest variation from an allotted frequency or wave-length is detected.

Historical article:

Typical Sales Advertisement from

The N.Z. Radio Times

February 2, 1937

It is generally agreed that if a receiver has to be operated where interference is directly radiated, the most effective way of improving reception is to attend to the aerial; the active span should be erected as far from any metallic conductor as possible, and the down lead which is incapable of picking up any radio voltages be used for connecting the aerial to the receiver.