Historia komunikacji Zemia - Księżyć - Ziemia (EME) dyletantowi Czerepakowi Miszy dedykuję Wyśmiany system anten przez dyletanta Miszę Czerep

Project Moonbeam The US Military projects presented in the previous sections were very ambitious and involved hundreds if not thousands of scientists and engineers. However, in parallel with these large scale EME efforts a small number of radio amateurs, mainly from the US, were planning their own attempts at ‘reaching the Moon’, using more modest equipment. Naturally, these radio amateurs were faced with the same technical challenges as the military. Their solutions on the other hand, were seriously restricted due to economical reasons, the output powers were lower and the dishes were smaller, calling for narrow-band communication. With technology nowhere near today’s standards, especially in regard to UHF and microwave receiver front-ends, the author reckons that the challenge must have been quite a bit bigger than today. Nevertheless, eventually came the success of Project Moonbeam, a joint effort between two American radio amateurs by the name of Ross Bateman (W4AO) and Bill Smith (W3GKB). After numerous unsuccessful attempts they finally succeeded in hearing their own 144 MHz echoes at 5:03 AM, 15 July 1950. The output power of their system amounted to 1 kW, which was fed into a 20 wavelength stacked rhombic array antenna. However, although their echoes were recorded they were also very weak. Thus instead of making their success public, they decided to continue their work on improving the equipment. Joined by Ted Tuckerman (W3LZD) in their quest for stronger echoes, it would take the trio another two and a half years of hard work and testing, before breakthrough came on 27 January 1953. The results of this work is shown in fig. 2.4, presenting a series of two strong echoes recorded on that day. The amateur radio community had to wait another seven years though, until it could finally witness the first two-way EME contact between amateur radio stations, on 21 July 1960. It was established on 1296 MHz between the ‘Rhododendron Swamp VHF Society’ (W1BU) in Massachusetts and the ‘Eimac Radio Club’ (W6HB) in California. This milestone sparked an increased interest in EME communication among radio amateurs worldwide. New records followed and on 11 April 1964 the first two-way contact between the US and Europe was established on 144 MHz, between Bill Conkel (W6DNG) in California and Lenna Suominen (OH1NL) in Finland. Two fantastic opportunities were given in June 1964 and July 1965, when the largest telescope in the world, the Arecibo Observatory in Puerto Rico , engaged in amateur radio EME communication on 144 and 432 MHz, operating under the KP4BPZ call sign. The Arecibo dish is 300 metres in diameter, which enabled radio amateurs from around the world to establish two-way contacts using Morse code and very modest equipment. More capable stations were even successful in using voice communication. It would take another 45 years, in April 2010, until radio amateurs were once again given the opportunity to operate from the Arecibo observatory, this time using the KP4AO call sign, on 432 MHz. This time around, JT65B digital communication was also used. See fig. 2.5 for a photo of the Arecibo antenna! The first strong amateur radio EME echoes, recorded on 27 January 1953 as part of Project Moonbeam. The pioneers behind this feat were Ross Bateman (W4AO), Bill Smith (W3GKB) and Ted Tuckerman (W3LZD). Reprinted with the permission of the ARRL. Copyright © ARRL.) The 300 metre dish at the Arecibo Observatory in Puerto Rico. It was used by radio amateurs for EME communication in 1964, 1965 and 2010. (Photo courtesy of the NAIC – Arecibo Observatory a facility of the NSF.)

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