se of the nature of propagation at these frequencies, it is unlikely that these stations will achieve much coverage within their own country, unless the skip distance falls within the country. As a result short wave stations are used as flagships for their countries. Often they carry propaganda. This was particularly true in the days of the cold war. Stations from the West could be heard giving exactly the opposite views to those from the Eastern Bloc. Even today short wave broadcast stations are still used for this purpose. However, many stations seek to give their countries credibility on the international scene by producing good reliable programming and news. The BBC World Service is recognized the world over as possibly the best station. There are also many religious stations on the air including stations like Vatican Radio, and HCJB which broadcasts from the Andes. Sometimes the short wave bands are used for domestic broadcasting. Many of the countries in the tropical areas of the world are large and relatively sparsely populated. This means that it is not possible to obtain adequate coverage with either medium wave or VHF FM transmissions. In countries like the UK 20 or more stations may be required to give reasonable coverage for a national network. In countries which are possibly larger and are less densely populated it is not economically 206 Newnes Guide to Radio and Communications Technology Table 7.1 Broadcast allocations up to OMHz Long wave 0.150-0.285 Medium wave 0.5265-1.6065 120 metres 2.300-2.495* 90 metres 3.200-3.400* 75 metres 3.900-4.000** 60 metres 4.750-5.060* 49 metres 5.950-6.200 41 metres 7.100-7.300** 31 metres 9.500-9.990 25 metres 11.650-12.050 22 metres 13.600-13.800 19 metres 15.100-15.600 16 metres 17.550-17.900 13 metres 21.450-21.850 11 metres 25.670-26.100 All frequencies are in MHz. * Tropical bands only for use in tropical areas. ** Only allocated for broadcasting in Europe and Asia. viable to operate as many transmitters. Coupled with this it is just as important to ensure t