【火腿快新闻】215、4095公里 | 新的微波、分米波传输距离记录在同一天诞生
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编译：BD7TQ
新的微波、分米波传输距离在同一天诞生
新的传输距离纪录分别在47GHz和902 MHz于6月30日由在地面上两个超长距离的站点完成。在47GHz，美国和加拿大的业余爱好者分别在美国纽约的Whiteface山 (FN34bi)和加拿大魁北克Tremblant山(FN26rf)上设台，两个地点的爱好者们努力尝试建立47GHz频率上新的美国到加拿大传播距离记录，两点的测量直线距离是215公里（133.3 英里）。在美国一边是N1JEZ和KT1J,在加拿大这边是VE2UG和VE3FN。
“在这个频段，通常是视线传播方式”N1JEZ Seguin说到，“我们有大量的实验要做，现在有一些非常棒的功率放大器可以帮助我们实验”，他说6月30日的尝试，标志着VE2UG和VE3FN在47GHz频率上的第二次通联。一周前，他们曾在99公里(61.4英里)的路径上与KT1J和N1JEZ一起合作通联过，当时信号峰值比背景噪声高了将近60分贝。
在6月30日这个特别的日子，山顶上所设备都准备好后，Seguin N1JEZ 几乎马上可以听到Barbe VE2UG的CW信号。"信号不是很强，并且有出现很多衰落QSB的情况" Seguin N1JEZ说到. 一旦两边的爱好者将他们的抛物面天线对准后，VE3FN和N1JEZ在47GHz频率上成功进行了通联，接下来他们又轻松的在24GHz频率上进行SSB通联。
北美在47GHz频率上的最远通联记录是在2015年创造的，距离是344.8公里(213.8英里)。
同时在地球的另一端太平洋，N6NB 和 W6IT 在夏威夷和加州之间创造了902MHz频率传输记录的新世界纪录。他们利用跨太平洋对流层大气波导完成了4095公里（2544英里)长距离的SSB通联，打破了20年前创造的4064公里的旧记录。这与去年N6NB和 W6IT在2.3GHz和3.4GHz频率上创造的新传播距离世界记录估计为同一个传播路径。
“这个超长距离的通联记录再次证明，记录的创造除了有好的运气外还要有好的规划和准备”N6NB说到。不仅仅是跨太平洋对流层大气波导在去年让N6NB和W6IT完成了他们的超长距离微波传输距离记录，直到6月30日为止，事实上还存在一些其他的大气波导路径。“这个大气波导仅仅出现了几个小时的传播窗口”N6NB回忆到，他说他和W6IT都选择了正确的地点和正确的时间创造了新的902MHz传输距离世界纪录。“三个小时后，这个大气波导消失了，传输的跨太平洋信号完全衰落为噪音“，N6NB说“某些大气波导的存在可以持续8天之久，但这一个只区区几个小时”。
N6NB在夏威夷进行呼叫，他在位于海拔5260英尺的夏威夷Daniel Inouye高速公路上用了一套架设在租用汽车上的便携式通联设备，同时在加州，W6IT在高度6200英尺的海拔和75英里的内陆，用N6NB设计的便携式设备进行通联。
“这个计划存在一定的风险”N6NB说，“跨太平洋对流大气波导偶尔开通美国东部海岸到夏威夷的VHF信号的传输通道，但通常只发生在加州的低海拔地区到夏威夷的高海拔地区”。
N6NB说，当加州岸边的高山顶上的电波无法传输到大气波导时，其海拔地区就能够有机会容易的通联到夏威夷。
“大气波导通常发生在加州一端海岸线附近，但有时架设的站点在远离海岸线但还能看到海岸线的高山顶上时，有利于将信号以一个低角度送进大气波导中，W6IT的架设地点就是这样一个地方, 在内陆但可以看到大海。“
New Microwave, UHF Distance Records Set on Same Day
New distance records were set on 47 GHz and on 902 MHz on June 30 by stations at vastly separated points on the globe. On 47 GHz, US and Canadian operators set up on Whiteface Mountain in New York (FN34bi) and on Mont Tremblant in Quebec (FN26rf), respectively, in the effort to set a new North American record on the band. The distance was calculated at 215 kilometers (133.3 miles). On the US side were Mike Sequin, N1JEZ, and Henry Ingwersen, KT1J; on the Canadian side were Rene Barbeau, VE2UG, and Ray Perrin, VE3FN.
“On this band, we usually are working line of sight,” Sequin said. “We have a lot of experimentation to do, now that there are some good high-power amps available.” He said the June 30 attempt marked the second 47 GHz contact for VE2UG and VE3FN. A week earlier, they had worked both KT1J and N1JEZ over a 99-kilometer (61.4 miles) path, with signals peaking almost 60 dB out of the noise.
Once everything was in place on the big day, Sequin was able to hear Barbeu’s CW signal almost immediately. “Signals were not strong, with a lot of QSB,” Seguin said. Once they aligned their dishes, each operator worked the others. Following the successful 47 GHz contacts, VE3FN and N1JEZ worked each other “easily” on 24 GHz SSB.
Meanwhile on the Pacific side of the world, Wayne Overbeck, N6NB, and Greg Campbell, W6IT, set a new world DX record on 902 MHz between California and Hawaii. They took advantage of a transpacific tropo duct to complete an SSB contact over a path of 4095 kilometers (2544 miles), topping the old record set more than 20 years ago of 4064 kilometers. Last year, Overbeck and Campbell set world distance records on 2.3 and 3.4 GHz over the approximately the same path.
“This record contact again underscored the degree to which these record-setting attempts involve good luck as well as planning and preparation,” Overbeck said. Not since the tropo duct that allowed Campbell and Overbeck to set their microwave records last year had another occurred, until June 30. “This duct only produced good signals for a matter of a few hours,” he recounted. He said he and Campbell both managed to be in the right place at the right time to set the new 902 MHz record. “Three hours later the duct dissipated and transpacific signals faded into the noise,” he said. “Some ducts have been known to last for as long as 8 days, but this one was gone in a few hours.”
N6NB operated from Hawaii using a suitcase portable station in a rented vehicle at 5260 feet elevation on Hawaii’s Daniel Inouye Highway, while in California, W6IT used one of N6NB’s rover stations to operate portable 75 miles inland and at 6200 feet elevation.
“That strategy was admittedly risky,” Overbeck said. “The transpacific tropo duct, which occasionally allows VHF+ signals to travel from the West Coast to Hawaii, usually occurs at a low elevation on the California end, but at a high elevation on the Hawaiian end.”
He said there have been occasions when California stations on coastal mountaintops could not get into the duct, while stations at much lower elevations were easily able to work into Hawaii.
“The duct usually breaks up near the shoreline on the California end,” Overbeck said. “Sometimes stations on a mountaintop that is far enough inland but still line of sight to the coast can put a signal into the duct from afar at a low angle. W6IT’s location at an overlook on Rim of the World Drive is that kind of place — far inland but line of sight to the ocean.”
Source:ARRL
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