Low Frequency Wireless Telecommunications and Shared Frequency-Allocation Links, etc.

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FCC Part 15.217 Operation in the band 160-190 kHz.
(a) The total input power to the final radio frequency stage (exclusive of filament or heater power) shall not exceed one watt.  (b) The total length of the transmission line, antenna, and ground lead (if used) shall not exceed 15 meters.  (c) All emissions below 160 kHz or above 190 kHz shall be attenuated at least 20 dB below the level of the unmodulated carrier.  Determination of compliance with the 20 dB attenuation specification may be based on measurements at the intentional radiator's antenna output terminal unless the intentional radiator uses a permanently attached antenna, in which case compliance shall be demonstrated by measuring the radiated emissions.

Part 5 Experimental Radio Stations:

Additional 2,200 meter stations:

DL4YHF's Amateur Radio Software "Spectrum Lab" (Download Site) 

Lyle Koehler's LowFER Receiver Using a Software IF-B 

The Noise Floor: 1750 Meters Resource Page 

More LowFer pages 

RF Current Probes 

Weaksignals Home Page 

Argo a QRSS/DFCW slow CW viewer 

Distance between two points 

| <---------------


--------------->    |
-- .   . --
71.6 74.4

73 kHz Band

DCF54 | <------------ 2.1kHz ------------> | DBF39/TBA
- . - . . . . . - . -
134.2 135.7 136.75 137.8 139.0

136 kHz or 2200 meter Amateur Radio Band

Frequency Allocation Chart
U.S. and International RF spectrum allocations extending from 9 kHz to 300 GHz

The Electromagnetic Spectrum
including a frequency-wavelength conversion utility.

Frequency-to-wavelength Conversion

Very Low and Low Frequency Radio Stations

Site ID Frequency (kHz) Wavelength (meters) Radiated Power (kW)
Royal Navy, Gippsland, Woodside, Australia VL3DEF 13.0000    
Batumi, Russia UVA 14.6000   100*
Vladivostok, Russia UIK 15.0000 20,000.0000 100*
Rosnay, France HWU 15.1000   400
Bombay, India   15.1000    
Rugby, United Kingdom GBR 16.0000   45
Noviken, Norway JXN 16.4000   45
St. Assie, France FTA 16.8000   23
Varberg Sweden (Grimeton Radio) SAQ 17.2000    
Cutler, Maine   17.8000    
USN TACAMO mobile worldwide unidentified 17.9000    
Matotchkinchar, Russia UFQE 18.1000   100*
Katabomman, S. Vijayanarayanam village, India VTX3 18.2000    
Rhauderfehn, Germany   18.5000   500
Anthorn, United Kingdom GQD 19.0000   42
Arkhanghelsk, Russia UGE 19.4000   150*
Criggons, United Kingdom GBZ 19.6000   44
Harold E. Holt, Australia NSW 19.8000   1000
Amundsen/Scott South Pole base, Antarctic unidentified 20.0000 15,000.0000  
Isola di Tavolara, Italy ICV 20.2700   43
Lualualei, Hawaii NPM 21.4000   480/566
Ebino Huyshu, Japan   23.4000    
Cutler, Maine NAA 24.0000   1800
Jim Creek, Washington NLK 24.8000   192/250
Various locations RAB99, etc. 25.0000 12,000.0000  
Omega Station, LaMoure, North Dakota   25.4000   silent
VLF upper limit, LF lower limit   30.0000 10,000.0000  
Kaliningrad, Russia UGKZ 30.3000   100*
    35.0000 8571.4286  
Keflavik, Iceland NRK 37.5000   100
Niscemi, Italy   39.9000   25
Japan JJY 40.0000 7,500.0000 50 kW
Aquada, Puerto Rico NAU 40.7500   100
Irkutsk, Russia (time standard) RTZ 50.0000 6,000.0000 50 kW
Ft. Collins (time standard) WWVB 60.0000 5,000.0000 50 kW ERP
Rugby (time standard) MSF 60.0000 5,000.0000  
Moscow RBU 66.6700    
    70.0000 4285.7143  
Aarjaeng, Hamburgsund & Vallda, Sweden   71.5830   30.8**
Jomfruland, Norway   71.5833   30.8**
73 kHz Amateur Radio Band - lower limit   71.6000 4189.9441  
Baku, Azerbaijan   72.0000   43.0**
St. Assise, France FTA72 72.1000   46.5**
Kostinbrod, Bulgaria LCI5 72.2000   41.1**
Baku, Azerbaijan   72.3000   43.0**
Shmidta MYS, Russia   72.3000   44.8**
Chittagong, Bangladesh   72.5000   43.0**
Karachi, Pakistan   72.5000   43.0**
Jeloey, Norway LCE 72.8500   46.5**
Ruiselede, Belgium ORL28 72.9000   40.0**
Dutch Harbor, Alaska   73.2500   47.0**
Kodiak, Alaska   73.2500   46.0**
Crimond, Scotland   73.2500   46.0**
Rugby, England MTO21 73.2500   46.0**
Arkhangelsk, Russia UGE 73.4000   41.8**
Halifax, Nova Scotia  CFH 73.6000   54.0**
Bombay, India    73.6000   50.0**
Deutsch Altnbg, Austria   73.8500   44.8**
Crimond, Scotland   74.2000   46.0**
London, England GYD 74.2000   40.0**
Akkul, Kazakhstan   74.2000   30.0**
Petrozavodsk, Russia   74.4000   33.0**
73 kHz Amateur Radio Band - upper limit   74.4000 4032.2581  
Koenigswusterh, Germany DKQ2 74.5000   43.0**
Kalsborg, Sweden SAY 74.5500   40.0**
Varberg, Sweden SAY 74.5500   47.0**
Nyon or Prangins, Switzerland (time standard) HBG 75.0000 4,000.0000  
Mainflingen, Germany (time standard) DCF77 77.5000    
Loran-C navigation system   100.0000 3,000.0000  
    108.0000 2777.7777  
Telekom Mainflingen DCF42 123.7000    
EFR Mainflingen DCF49 129.1000    
136 kHz Amateur Radio Band - lower limit   135.7000  2,210.7590  
WA2XTF   136.7500   Inactive
136 kHz Amateur Radio Band - upper limit   137.8000  2,177.0682  
EFR Burg DCF39 139.0000    
Hamburg Meteo DDH47 147.3000    
    157.1875  1908.5487  
License Free Expt. Band - lower limit   160.0000  1,875.0000  
Radio France International, Allouis   162..0000    
    171.4062  1750.2284 1*
"Watering Hole"   185.3000   1*
License Free Expt. Band - upper limit   190.0000  1,578.9474  
        *Input power

FCC Declines to Grant [the Requested 135.7-137.8 kHz] Amateur LF Allocation 

Report and Order 
     In evaluating whether amateur privileges should be added to the 135.7-137.8 kHz band the FCC considered the potential for interference conflicts with Power Line Carrier (PLC) operations associated with the national power grid.
     Accordingly, the FCC declined to make the 135.7-137.8 kHz allocation to the amateur service.  The FCC acknowledges there is potential for some limited operation under individual experimental licenses.  Low Frequency operations under the FCC experimental license program will allow amateur use to be coordinated with utility companies on a case-by-case basis, and allow empirical data to be developed on the sharing possibilities in this band for future consideration.  In addition, amateurs may still make use of the 160-190 kHz band under Part 15 rules, which are much more restrictive, and therefore more protective of PLCs, than the limits proposed in the Notice.

Notice of Proposed Rule Making (05/15/2002) *

ARLB095: ARRL Petitions FCC for LF Allocations *

ARRL Petition for Rule Making for LF Allocation for the Amateur Radio Service

136 kHz Band Would Mark First LF Allocation for [U.S.] Hams *

Low-Frequency Experimental License Issued *

AMRAD Low Frequency Web Page 

AMRAD Continues LF Experiments *

AMRAD LF Experimenters' List Archive 

CEPT draft recommendation on LF allocation to Radio Amateurs 

The Amateur Service seeks a shared LF allocation *

The Longwave Club of America — Promoting both DXing and experimentation on the frequencies below 550 kHz.

Simple LowFER Transmitter -- by Lyle Koehler, KØLR 

Three LF Transmitters *

QRS Ver 2.05 Download

136kHz at G3YMC

VK2ZTO Experimentation Pages

Altair LF Beacon YWK

BPSK Receiver []

How to Design a Class-E Transmitter for Your LowFER Beacon []

SM6LKM Beacon, etc.
    Build a simple isolated impedance bridge for LF antennas
    74HC4053 Longwave upconverter
    PIC controlled CW/BPSK beacon transmitter

Packet Digital Amateur Network — free software developed for radio amateur's use, including Argo and Jason.

ON7YD -- [Radio] Antennas for 136kHz

2.14. Helical antenna
In the helical antenna the loading coil (or a part of it) is incorporated in the vertical section of the antenna.  So with this antenna both capacitance and inductance are distributed over the entire antenna.  As the antenna voltage builds up over the loading coil, the antenna voltage increases with the height.  This voltage increase results in an improved current distribution, as in the lower part of the antenna (where the voltage is low) less current will 'disappear'.  Without capacitive top loading the radiation resistance of a helical antenna will be 1.54 times larger as for a 'straight' vertical of the same height, this is a gain of 1.9dB.  When capacitive top loading is added the advantage of a helical antenna will be less, for 2 reason :

  • As the antenna has more capacitive top loading the importance (and thus the gain) of the distributed inductance decreases.

  • As the capacitance of the vertical part of a helical antenna is rather large compared to a 'straight' vertical (because of the larger diameter of the vertical part) the effect (and thus the gain) of the capacitive top-loading decreases.

An additional problem is that it is not so easy to built a mechanical stable helical antenna.  The only amateur who,  to my knowledge, used a helical antenna with success was Toni Baertschi (HB9ASB), until the antenna was destroyed in a storm (December 1999).

3.2. Efficiency
If an antenna is fed with a certain power it will radiate a part of that power.  The remaining part is dissipated 'uselessly', in most cases converted to heat in or around the antenna. Simplified one can say that the transmitter feeds its power into 2 resistors, the radiation resistance (RA) and the loss resistance (RL).  The efficiency (®) of an antenna is,


On HF the efficiency of most antenna systems is very high, 90% or more. The most important sources of loss are skin effect in the antenna wires and dissipation in the transmission line (coax cable).  On VHF and higher frequencies these last can become very important.  On LF the situation is completely different, efficiencies of most antennas used by hams are in the range of 0.01 to 1%.  The source of these high losses is dependent on the type of antenna.  For electrical antennas the major losses will be mainly in the environment and the loading coil.  For transmitting the efficiency of the antenna system will directly affect the amount of radiated power and thus is very important. . . .

A 160 meter EH antenna Can be useful on 137 kHz (cylinder should be 6 m high x 2m diameter).

Teslavert  An 160 meter antenna based upon a classic Tesla coil *

High Power Solid State Tesla Coil

Long Wave Club of America-1

Long Wave Club of America-2

Integrated LF Preamplifier Using AD712 or CA3140A Op-Amp

Pierre Thomson, KA2QPG Longwave Page

A Universal LF/MF Preamplifier by Lyle Koehler, KØLR


High-Gain LF Preamp by Lyle Koehler, KØLR


E-field Whistler Receiver Design by Scott Fusare, N2BJW

Figure 2

Low Impedance Active Antenna

Click for larger view of circuit.

Long Wave Receiver and Antenna Files

The 137 kHz Low Power Transmitter []
A Project for the Impatient
A Project for the Impatient

This is a very short description of a tiny low power cw transmitter for long wave. They have permit in Germany since January 1999. Depending on the PI-Filter components and voltage for the final stage this transmitter would be able to reach the 100 Watts output level. Running two IRF630 in parallel they got more than 100 Watts of output "key-down" (16.5V/9A at full load).

300 W  136kHz Transmitter
Single Printed Circuit Board 178 x 128mm   including:
Variable Crystal Oscillator
Low Pass Filter
Tx / Rx switching relays
'Optically coupled' over-current protection
VSWR Protection

The circuit is based around a high efficiency class D amplifier which uses two STW34NB20 power MOSFETS. Rated at 200V and 34 Amps these FETs combined with protection circuits that can respond to fault conditions in a few tens of microseconds make for an extremely robust design.

The power output is dependent on the output matching transformer. If one 42mm 3C85 core is used, the maximum power is just over 300W.  If two cores are stacked, the power rating is increased to 400W


Pictures (Click to enlarge)
    Front View 28kb        Rear View 33kb       Internal View 40kb       Side View 38kb

The prototype transmitter pictured above is designed to produce 400W output from a 45V supply.  The output matching transformer used is not the toroidal type shown in the parts list. The core here is an ETD44 using a siemens N30 core material. Although the transformer works well, it is difficult to reproduce. Consequently, the toroidal form is recommended as it's easier to construct.

A kit of parts is available., G0MRF HOME

Isotron HF Antennas for small spaces

Spectrogram Version 6 Downloads

Solar Cycles 22-23

The INSPIRE Project *

Radio Jove

Very Low Frequency Group


AntenneX  One of this magazine’s main goals is to provide a place for the exchange of ideas and publication of antenna and radio-related subjects from all parts of the globe so we could all share and learn how things are done from all viewpoints in this ever-shrinking world. We am happy to say this goal is being met quite well with writers from about 25 countries now represented in the thousands of pages in this magazine.

Radio Society of Great Britain

International Telecommunications Union   

Radio Propagation Bibliography *

Longwave Technology [Original source deleted from world wide web]
In part 15 of the FCC rules there is a provision for unlicensed operation in a number of frequency bands.  One of these is 160 - 190 kHz.  You are allowed a total feed plus antenna length of 15 meters (about 50 feet) and an input power of 1 Watt.  Since a high-Q antenna circuit is required the bandwidth limits the mode to very narrow band modes such as CW or narrow band digital modes. The Longwave Club of America is for "Lowfers".  In order to get good results you need a high-Q coil.  In order to learn about the subject of high-Q coils [author] spent a couple of years finding and reading out of print books about inductors and got a Boonton Model 160 Q-meter and did a great many experiments.
Lyle Koehler, KØLR - This page is dedicated to LF experimenting and home brewing
GWEN - These sites are going to be converted to GPS differential correction sites to serve the land mass of the CONUS.
Secretary of the Air Force - US3984839: Low height VLF antenna system  -
Navaid Information - List Server - send mail to:, leave subject field blank, in the text enter: subscribe lofer
IK1QFK Home Page: Exploring ULF-ELF and VLF radio band -
Submarine Communications Shore Infrastructure - also see SOSUS & the Glomar Explorer -
Kiwa - Earth Monitor - 10 Hz to 15 kHz.
AMRAD Low Frequency - Modifying the RX320 Receiver for LF/VLF Operation -
LF Engineering - active whips & other LW hardware 
New England Electric Wire Corp - Litz wire manufacturer
MWS Wire Industries - Litz wire -
Cooner Wire - Litz wire 
Amidon - Ferrite Rods, Bars, Plates and Tubes and Iron Power, pot cores - and application notes

Brooke Clarke's Time & Frequency page