निम्न आवृत्ति (LF)

निम्न आवृत्ति या LF वे रेडियो आवृत्ति होती हैं, जो कि 30 kHz–300 kHz के मध्य आती हैं। इसे किलोमीटर पट्टी या तरंग भी कहते हैं। क्योंकि इसका तरंग दैर्घ्य दस से एक किलोमीटर होता है।

सामरिक प्रयोग

प्रयोग एवं अमेच्योर 
A 2.1 kHz allocation, the 136 kHz band (135.7 kHz to 137.8 kHz), is available to amateur radio operators in some countries in Europe, New Zealand and French overseas dependencies. The world record distance for a two-way contact is over 10,000 km from near Vladivostok to New Zealand. As well as conventional Morse code many operators use very slow computer controlled Morse code or specialized digital communications modes. A proposal at the WRC-07 World Radiocommunication Conference aims to make this a worldwide amateur radio allocation.

The UK allocated a 2.8 kHz sliver of spectrum from 71.6 kHz to 74.4 kHz beginning in April 1996 to UK amateurs who applied for a Notice of Variation to use the band on a noninterference basis with a maximum output power of 1 W ERP (effective radiated power). This was withdrawn on 30 जून 2003 after a number of extensions in favor of the European-harmonized 136 kHz band. A 1-watt transmission of very slow Morse Code between G3AQC (in the UK) and W1TAG (in the USA) spanned the Atlantic Ocean for 3275 miles on November 21-22, 2001.

In the United States there is a special license free allocation in the longwave range called LowFER. This experimental allocation between 160 kHz and 190 kHz is sometimes called the "Lost Band". Unlicensed operation by the public is permitted south of 60 degrees north latitude, except where interference would occur to ten licensed location service stations located along the coasts. Regulations for use include a power output of no more than 1 watt, and an antenna/ground-lead length of no more than 15 meters, and a field strength of no more than 4.9 microvolts/meter. Also, emissions outside of the 160 kHz–190 kHz band must be attenuated by at least 20 dB below the level of the unmodulated carrier. Many experimenters in this band are amateur radio operators.

मौसम संबंधी प्रसारण 

A regular service transmitting RTTY marine meteorological information on LF is the German Meteorological Service (Deutscher Wetterdienst or DWD). The DWD operates station DDH47 on 147.3 kHz using standard ITA-2 alphabet with a transmission speed of 50 baud and FSK modulation with 85 Hz shift.

रेडियो नौवहन संकेत

रेडियो प्रसारण 

यह प्रसारण होता है 148.5 से 283.5 kHz के मध्य, यूरोप एवं एशिया के भागों में।

एण्टीना 

रेडियो
वर्णक्रम
विज्ञान
विद्युत चुम्बकीय वर्णक्रम