Fig. 3. Effects of longitude offsets at 60° latitude. from 36°N to 72°N, while the USA has a northern border at 50°. One of the most important questions arising from this fact is that of the land use for the receiving areas and for safety zones if necessary. Our definitions of safety zones (Figure 1) refer to a 10 dB Gaussian power distribution within the microwave beam. More recent studies point towards a 14-step 17 dB Gaussian distribution where the peak level of the first sidelobe lies already beneath the USSR limit but where the actual rectenna area has to be increased for the same interception efficiency as before. Figure 2 shows the dependence of the receiving-site dimensions on latitude. Since the extension of W. Europe in longitude is relatively small, and some electricity consumption centers might be located at the same longitude, the effects of longitude offsets have to be taken into consideration for the receiving-site dimensions. Figure 3 shows the rectenna area variation for a 60° rectenna due to longitude offsets up to 35°. Western Europe has, however, a good potential for placing rectennas offshore (see Figure 4). The coastline has a length of about 15,000 km compared to 7000 km for the USA and several parts of the coastal waters are very shallow, particularly in the North Sea. The advantages of offshore rectennas would be: 1. There would be no inhabitants near the rectenna if it were placed about 10 km off the coast, and so the sidelobe levels would not be critical, 2. No people would have to be relocated for the clearance of the receiving site, 3. No land would have to be bought for rectenna sites and safety areas, and 4. Existing terrestrial infrastructure would not have to be changed (roads, rails etc.). Problems are, however, expected with: 1. Higher construction cost (sea-walls, piles or floats as support structure for the arrays, etc.),
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