Amateur Radio Bands (UK)

This section covers the amateur radio bands available to UK amateur license holders. The reason for such specificity is that other countries have similar, but sometimes slightly different frequency allocations and power limits. It would be quite an undertaking to catalogue all allocations in all countries.
Once the core pages and sections here are complete, I may add separate pages for other countries and may even put together a record of things like marine and aeronautical frequencies.

Power limit:
1000W PEP, subject to the licence conditions applicable to the operator.
The UK 10 MHz allocation is a secondary amateur allocation.

Day:
Regional and medium-distance propagation is common, with reliable communication over several hundred kilometres. Longer-distance skywave propagation can occur, particularly when the ionosphere is sufficiently ionised.

Night:
Long-distance (DX) propagation becomes more prominent, with intercontinental paths frequently possible. The band can support both regional and long-distance contacts throughout the hours of darkness.

D Layer:
Significant absorption during daylight, particularly at lower angles of incidence. Absorption decreases substantially after sunset, allowing more distant skywave signals to propagate.

E Layer:
Can support shorter-distance skywave propagation and may occasionally produce unusual propagation through sporadic-E. Its influence is generally secondary to that of the F-layer.

F Layer:
Provides the principal mechanism for long-distance skywave propagation. At night, the F-layer can support multiple-hop propagation over very long distances.

Solar activity:
Moderate to high solar activity can improve 40-metre DX by increasing F-layer ionisation, although increased ionisation can also increase daytime D-layer absorption. The band remains useful across a wide range of solar conditions.

Noise:
Atmospheric noise is generally moderate to high, particularly during thunderstorms. Man-made electrical noise can also be significant, especially in built-up areas.

Best conditions:
Generally best from late afternoon through the night and into the early morning. After sunset, reduced D-layer absorption allows longer-distance propagation, while sunrise can provide another period of enhanced DX activity. The band is often useful throughout the 24-hour cycle, with the character of propagation changing considerably between day and night.

Power limit:
400 W PEP, subject to the licence conditions applicable to the operator.
The UK 10 MHz allocation is a secondary amateur allocation.

Day:
Medium- to long-distance propagation is common, with the band often providing a useful balance between regional and DX communication. Unlike the lower HF bands, 10 MHz can remain effective during daylight when D-layer absorption is present.

Night:
Long-distance (DX) propagation becomes more prominent, with intercontinental paths frequently possible. The band can remain useful throughout the hours of darkness, although propagation generally favours longer paths at night.

D Layer:
Causes some absorption during daylight, but considerably less than on 1.8, 3.5 and 7 MHz. Its influence decreases substantially after sunset, allowing weaker and more distant signals to become easier to receive.

E Layer:
Can occasionally support shorter-distance skywave propagation and unusual propagation through sporadic-E. Its normal contribution to 10-metre propagation is relatively limited compared with the F-layer.

F Layer:
Provides the principal mechanism for long-distance skywave propagation. The band is particularly useful for F-layer propagation because it can support DX while remaining less affected by D-layer absorption than the lower HF bands.

Solar activity:
Moderate to high solar activity generally improves long-distance propagation by increasing F-layer ionisation. However, 10 MHz remains relatively dependable during low solar activity and can provide DX when higher HF bands are closed.

Noise:
Atmospheric noise is generally lower than on 1.8, 3.5 and 7 MHz, although thunderstorms can still produce significant interference. Man-made electrical noise can also affect reception, particularly in populated areas.

Best conditions:
Generally useful throughout the day and night, making 10 MHz one of the more consistent HF bands for longer-distance communication. Daytime often favours medium- and long-distance paths, while after sunset the band can provide reliable DX as lower-frequency bands become more affected by congestion and noise.

Power limit:
400 W PEP, subject to the licence conditions applicable to the operator.

Day:
Long-distance propagation is predominant, with 20 metres regarded as one of the principal bands for worldwide DX. F-layer propagation can provide intercontinental paths for much of the daylight period, even during relatively low solar activity.

Night:
Long-distance propagation can continue after sunset, particularly during periods of higher solar activity. During lower solar activity, the band is more likely to close as the MUF falls below 14 MHz on some paths.

D Layer:
Causes relatively little absorption compared with the lower HF bands. Daytime absorption is generally low enough for 14 MHz signals to reach the F-layer effectively.

E Layer:
Can occasionally support short-distance skywave propagation, particularly during periods of sporadic-E activity. Under normal conditions, its role in 20-metre DX is relatively minor.

F Layer:
Provides the principal mechanism for long-distance skywave propagation. F2-layer propagation is responsible for the majority of worldwide 20-metre DX, with multiple-hop paths allowing signals to travel across continents and oceans.

Solar activity:
Higher solar activity generally improves 20-metre DX by increasing F-layer ionisation and raising the MUF. The band remains one of the most reliable HF bands for long-distance propagation even during lower points of the solar cycle.

Noise:
Atmospheric noise is generally relatively low compared with the lower HF bands, making weak DX signals easier to receive. Man-made electrical noise can still be significant, particularly in populated areas. The popularity of the band also means that congestion can be a greater problem than natural noise.

Best conditions:
Generally best during daylight and into the early evening, when the F-layer is sufficiently ionised to support long-distance propagation. Around sunrise and sunset, changing propagation conditions can produce particularly interesting DX openings. During periods of high solar activity, 20 metres can remain open to distant locations well into the night.

Power limit:
400 W PEP, subject to the licence conditions applicable to the operator.
The UK 18 MHz allocation is a secondary amateur allocation.

Day:
Long-distance propagation is common, particularly during periods of moderate to high solar activity. The band can support intercontinental communication when the MUF is sufficiently high, although openings are generally less reliable than on 14 MHz.

Night:
Long-distance (DX) propagation may continue after sunset, particularly during periods of favourable solar activity. However, the band is more likely to close at night than 14 MHz, as ionospheric ionisation decreases and the MUF falls.

D Layer:
Causes relatively little absorption at 18 MHz compared with the lower HF bands. Its influence decreases after sunset, but D-layer absorption is generally not the main limiting factor for 17-metre propagation.

E Layer:
The normal E-layer generally has a limited role in 17-metre propagation. Sporadic-E can occasionally support unusual short- to medium-distance paths, although it is more commonly associated with the higher HF and VHF bands.

F Layer:
Provides the principal mechanism for long-distance skywave propagation. F-layer refraction can support intercontinental paths, particularly when ionisation is sufficient to raise the MUF above 18 MHz.

Solar activity:
Moderate to high solar activity generally favours 17-metre DX by increasing F-layer ionisation and raising the MUF. During periods of low solar activity, the band becomes less reliable, particularly for longer paths and at night.

Noise:
Atmospheric noise is generally relatively low compared with the lower HF bands, making weak DX signals easier to receive. Man-made electrical noise can still be significant, particularly in populated areas.

Best conditions:
Typically during daylight and into the early evening, when F-layer ionisation is sufficient to support long-distance propagation. The band is particularly useful during periods of moderate to high solar activity, with openings often occurring around sunrise and sunset as propagation conditions change.

Power limit:
1 kW PEP, subject to the licence conditions applicable to the operator.

Day:
Long-distance propagation is common, with 15 metres providing excellent opportunities for intercontinental DX when ionospheric conditions are favourable. The band is generally more dependent on solar activity than 20 metres, but can remain open for substantial periods during the day.

Night:
Long-distance propagation can continue after sunset, particularly during periods of higher solar activity. However, the band is more likely to close at night than 20 metres as ionisation decreases and the MUF falls below 21 MHz.

D Layer:
Causes relatively little absorption compared with the lower HF bands. Daytime absorption is generally not the main limitation on 15-metre propagation, although it can still affect weaker signals.

E Layer:
Normally has a limited role in 15-metre propagation. Sporadic-E can occasionally produce unusual short- and medium-distance paths, although it is not the normal mechanism for 15-metre DX.

F Layer:
Provides the principal mechanism for long-distance skywave propagation. F-layer propagation can support intercontinental and multi-hop paths when ionisation is sufficient for 21 MHz to remain below the MUF.

Solar activity:
Higher solar activity generally favours 15-metre propagation by increasing F-layer ionisation and raising the MUF. The band is therefore more strongly influenced by the solar cycle than 20 metres, with substantially better DX opportunities when solar activity is elevated. RSGB propagation reports, for example, have recorded daytime MUFs reaching approximately 21–22 MHz during favourable conditions.

Noise:
Atmospheric noise is generally relatively low compared with the lower HF bands. This can make weak DX signals easier to receive, although man-made electrical noise and band activity can still affect reception.

Best conditions:
Typically during daylight, particularly around late morning through the afternoon when F-layer ionisation is strongest. Sunrise and sunset can produce changing propagation conditions and additional DX opportunities. The band generally performs best during periods of moderate to high solar activity, when the MUF is more likely to remain above 21 MHz.

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