ARRL Petition for LF Operation

Andre' Kesteloot
Thu, 05 Nov 1998 09:34:55 -0500

> 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.