ARLB095: ARRL Petitions FCC for LF Allocations

Source: http://www.arrl.org/w1aw/1998-arlb095.html

ARLB095 ARRL Petitions FCC for LF Allocations

QST de W1AW 
ARRL Bulletin 95 ARLB095
From ARRL Headquarters 
Newington CT November 3, 1998
To all radio amateurs 

ARLB095 ARRL Petitions FCC for LF Allocations

The ARRL has petitioned the FCC to create two low-frequency Amateur Radio allocations at 136 kHz and at 160 kHz. ''These allocations will permit experimentation with equipment, antennas, and propagation phenomena in a small segment of the radio spectrum that has not been available to the Amateur Service for many years,'' the League's petition declared. The petition was filed with the FCC October 22.

Specifically, the League has proposed permitting CW, SSB, RTTY/data, and image emissions for amateurs in a 2.1-kHz ''sliver band'' from 135.7 to 137.8 kHz and in a 30-kHz segment from 160 to 190 kHz. The 135.7 to 137.8 kHz band adheres to the European Conference of Postal and Telecommunications Administrations (CEPT) band plan.

The ARRL has proposed allowing a transmitter output in both LF segments of 200 W PEP, but in no case greater than 2 W EIRP (effective isotropic radiated power). The League's petition points out that poor antenna efficiencies and ground-loss characteristics likely would keep EIRPs at less than 1 W. The two bands would be available to General and higher licensees.

Unlicensed experimenters--some of them hams--currently operate on LF in the US under the FCC's Part 15 rules. These limit transmitter input power to 1 W and impose substantial restrictions on the size of the antenna. The proposed allocations ''will provide the only low-frequency allocation for amateur use and will accommodate more flexible experimentation than is permitted under current Part 15 regulations,'' the League's filing said.

Hams would be secondary to the Fixed and Maritime Mobile services in the 136-kHz allocation, and secondary to the Fixed Service in the 160-190 kHz band. The League said its engineering surveys suggest that hams could operate in the two segments without causing problems to power line carrier (PLC) systems already active in that vicinity or to government assignments. Unallocated, Part 15 PLC systems are used by electric utilities to send control signals, data and voice.

Calculations included with the League's filing demonstrate how inefficient even relatively large radiators can be on LF. For example, at 200 W TPO (transmitter power output) and a 200 foot vertical radiator, efficiency is only in the range of 1%, yielding up to 2 W EIRP. A more practical setup--200 W TPO into a 100-foot vertical radiator (efficiency of 0.2%) would yield an EIRP of between 10 and 40 mW.

Several countries throughout the world already enjoy LF allocations. These include New Zealand, Great Britain, the Republic of Ireland, and several European nations.

A copy of the petition is available on ARRLWeb, http://www.arrl.org.

Page last modified: 01:49 PM, 31 Dec 1998 ET
Page author: w1aw@arrl.org
Copyright 1998, American Radio Relay League, Inc. All Rights Reserved.