Ama­teur radio fre­quen­cy allo­ca­tion is done by nation­al telecom­mu­ni­ca­tions author­i­ties. Glob­al­ly, the Inter­na­tion­al Telecom­mu­ni­ca­tion Union (ITU) over­sees how much radio spec­trum is set aside for ama­teur radio trans­mis­sions. Indi­vid­ual ama­teur sta­tions are free to use any fre­quen­cy with­in autho­rized fre­quen­cy ranges; autho­rized bands may vary by the class of the sta­tion license.

Radio ama­teurs use a vari­ety of trans­mis­sion modes, includ­ing Morse code, radiotele­type, data, and voice. Spe­cif­ic fre­quen­cy allo­ca­tions vary from coun­try to coun­try and between ITU regions as spec­i­fied in the cur­rent ITU HF fre­quen­cy allo­ca­tions for ama­teur radio. The modes and types of allo­ca­tions with­in each range of fre­quen­cies is called a band­plan, and may be set by inter­na­tion­al agree­ments, nation­al reg­u­la­tions, or agree­ments between ama­teur radio oper­a­tors.

Nation­al author­i­ties reg­u­late ama­teur usage of radio bands. Some bands may not be avail­able or may have restric­tions on usage in cer­tain coun­tries or regions. Inter­na­tion­al agree­ments assign ama­teur radio bands which dif­fer by region.

160 meters – 1.8−2 MHz(1800–2000 kHz) – Often tak­en up as a tech­ni­cal chal­lenge; as long dis­tance (DX) prop­a­ga­tion tends to be more dif­fi­cult due to high­er D-lay­er ionos­pher­ic absorp­tion. Long dis­tance prop­a­ga­tion tends to occur only at night, and the band can be noto­ri­ous­ly noisy par­tic­u­lar­ly in the sum­mer months. 160 meters is also known as the “top band”. Allo­ca­tions in this band vary wide­ly from coun­try to coun­try. This band lies just above the com­mer­cial AM broad­cast band.

 

80 meters – 3.5−4 MHz (3500–4000 kHz) – Best at night, with sig­nif­i­cant day­time sig­nal absorp­tion. Works best in win­ter due to atmos­pher­ic noise in sum­mer. Only coun­tries in the Amer­i­c­as and few oth­ers have access to all of this band, in oth­er parts of the world ama­teurs are lim­it­ed to the bot­tom 300 kHz or less. In the US and Cana­da the upper end of the sub-band from 3600–4000 kHz, per­mits use of sin­gle-side­band voice as well as ampli­tude mod­u­la­tion, voice ; often referred to as 75 meters.

60 meters – 5 MHz region – A rel­a­tive­ly new allo­ca­tion and orig­i­nal­ly only avail­able in a small num­ber of coun­tries such as the Unit­ed States, Unit­ed King­dom, Ire­land, Nor­way, Den­mark, and Ice­land, but now con­tin­u­ing to expand. In most ( but not all ) coun­tries, the allo­ca­tion is chan­nel­ized and may require spe­cial appli­ca­tion. Voice oper­a­tion is gen­er­al­ly in upper side­band mode and in the USA it is manda­to­ry.

40 meters – 7.0–7.3 MHz – Con­sid­ered the most reli­able all-sea­son DX band. Pop­u­lar for DX at night, 40 meters is also reli­able for medi­um dis­tance (1500KM) con­tacts dur­ing the day. Much of this band was shared with broad­cast­ers, and in most coun­tries the bot­tom 100 kHz or 200 kHz are avail­able to ama­teurs. How­ev­er, due to the high cost of run­ning high pow­er com­mer­cial broad­cast­ing facil­i­ties; decreased lis­ten­er-ship and increas­ing com­pe­ti­tion from net based inter­na­tion­al broad­cast ser­vices, many ‘short wave’ ser­vices are being shut down leav­ing the 40 meter band free of oth­er users for ama­teur radio use.

30 meters – 10.1–10.15 MHz – a very nar­row band, which is shared with non-ama­teur ser­vices. It is rec­om­mend­ed that only Morse Code and data trans­mis­sions be used here, and in some coun­tries ama­teur voice trans­mis­sion is actu­al­ly pro­hib­it­ed. Not released for ama­teur use in a small num­ber of coun­tries. Due to its loca­tion in the cen­tre of the short­wave spec­trum, this band pro­vides sig­nif­i­cant oppor­tu­ni­ties for long-dis­tance com­mu­ni­ca­tion at all points of the solar cycle. 30 meters is a WARC band. “WARC” bands are so called due to the spe­cial World Admin­is­tra­tive Radio Con­fer­ence allo­ca­tion of these new­er bands to ama­teur radio use. Ama­teur radio con­tests are not run on the WARC bands.

20 meters – 14.0–14.35 MHz – Con­sid­ered the most pop­u­lar DX band; usu­al­ly most pop­u­lar dur­ing day­time. QRP oper­a­tors rec­og­nize 14.060 MHz as their pri­ma­ry call­ing fre­quen­cy in that band. Users of the PSK31 data mode tend to con­gre­gate around 14.071 MHz. Ana­log SSTV activ­i­ty is cen­tered around 14.230 MHz.

17 meters – 18.068–18.168 MHz – Sim­i­lar to 20m, but more sen­si­tive to solar prop­a­ga­tion min­i­ma and max­i­ma. 17 meters is a WARC band.

15 meters – 21–21.45 MHz – Most use­ful dur­ing solar max­i­mum, and gen­er­al­ly a day­time band. Day­time spo­radic-E prop­a­ga­tion (1500 km) occa­sion­al­ly occurs on this band.

12 meters – 24.89–24.99 MHz – Most­ly use­ful dur­ing day­time, but opens up for DX activ­i­ty at night dur­ing solar max­i­mum. 12 meters is one of the new WARC bands.

10 meters –28–29.7 MHz – Best long dis­tance (e.g., across oceans) activ­i­ty is dur­ing solar max­i­mum; dur­ing peri­ods of mod­er­ate solar activ­i­ty the best activ­i­ty is found at low lat­i­tudes. The band offers use­ful short to medi­um range ground­wave prop­a­ga­tion, day or night. Dur­ing the late spring and most of the sum­mer, regard­less of sunspot num­bers, after­noon short band open­ings into small geo­graph­ic areas of up to 1500 km occur due to Spo­radic-E prop­a­ga­tion. “Spo­radic-E” is caused by areas of intense ion­iza­tion in the E lay­er of the ionos­phere. The caus­es of Spo­radic-E are not ful­ly under­stood, but these “clouds” of ion­iza­tion can pro­vide short term prop­a­ga­tion from 17 meters all the way up to occa­sion­al 2 meter open­ings. con­tent

 


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