29th GHz-Conference Dorsten
Thunderstorms can clear the air, aid communication on the microwave frequencies, and can evidently also help make a conference again more interesting.
The frank discussion at the previous year's conference concerning the attendees' reluctance to prepare and present papers, had yielded a surfeit of dissertations for this year's event which made it necessary to extend the time allocated for the presentations by half an hour to accommodate all papers.
Clearly, all participants realized that a conference such as the GHz-Tagung can only be as good as the support given by participants.
On 18 February 2006, 220 GHz enthusiasts from DL and the surrounding countries, amongst them G, OZ, PA0, ON, HB9, met for the 29th conference despite the less than ideal weather conditions.
As always, the meeting was organized by OV Lembeck, N38, supported by district N and the VHS Dorsten.
Following the opening remarks by Peter Hoerig, DL4BBU, and the customary introductions of the participants, Ralf Benninghoff, DG6EA, was honoured for taking the initiative to design the conference website. DJ6XV thanked him on behalf of delegates and presented him with a small gift as a token of appreciation.
Following this, Alfred Schlendermann, DL9GS, the head of the Referat (department) Funksport (of the DARC) presented the cups to the winners in the three contest categories.
In the single operator category, nine-times winner Hans Harazim, DK2MN, was relegated to second place by Michael Kuhne, DB6NT, who convincingly won the cup for the first time. Norbert Richter, DL1SUN, came in third, reinforcing his position as a regular winner through the years.
In the multi-operator category several representatives from the "serial winners" at DL0GTH had shown up to receive the cup for the eighth time in succession. The new district chairperson of Thuringia, DL4APJ, had decided to attend the ceremony to personally congratulate 'his' contest group on their achievement. Representatives from the runners-up around DK3OS and third-placed DF0TEC were also represented to receive their prizes. The Ortsverband (OV) competition was won by OV Naila. This OV had in exemplary fashion managed to interest young radio amateurs in the microwave bands alongside their more experienced peers which had in no small measure made the very credible victory possible. Representatives from the runners-up and third-placed were also present to personally receive their respective cups.
Aside from applauding the successful competitors, delegates afforded special recognition to Alfred for his assiduous evaluations of the annual VHF, UHF and microwave contests. Alfred took the opportunity to announce his gradual withdrawal from his role as contest evaluator. This function will in future be taken on by a group as opposed to a single individual. Alfred's appeal for volunteers had so far, however, only drawn limited response.
The coordinator of the VHF/UHF/SHF-Referat of the DARC, Hellmuth Fischer, DF7VX, reported on recent developments in the UHF/SHF spectrum. Among other things he reported on the IARU Region 1 Conference which he had attended as the DARC's representative.
Probably the most important news for the microwave amateur community is the fact that the planned re-arrangement of the band at 76 GHz is not now going to happen and that the narrow-band segment in the 47 GHz band (47088 through 47090 GHz) has finally been fixed.
The conference's technical sessions commenced with a paper that Jürgen Dahms, DC0DA, had already finished just two weeks after the end of the last conference. He had already pointed out in his paper last year that the era of 'fundamental' discoveries on the microwave bands was over and that well designed kits or technically advanced complete modules now provide the basis for individually designed transverters.
He stressed that in addition to basic design considerations, thoughts should always be given to the equipment's intended application. Jürgen introduced a dual-band unit for the 23 cm and 13 cm bands intended for portable use, specifically the BBT. As usual, he described the construction of the unit in great detail, starting with component selection through to the successful function test.
The following presenter, Wolf-Henning Rech, DF9IC, looked at 'QRM in contests - measurement results for two-meter stations'. The paper's title did not, at first sight, appear to indicate a topic of particular relevance to a conference on the GHz spectrum. However, it quickly became clear that Wolf-Henning's analysis of the quality of emissions in the two-meter band also applied to the microwave bands. This even more so as two-meter band equipment routinely serve as the IF stage for microwave transverters. In his very technically demanding dissertation Wolf-Henning demonstrated the causes of the often poor emission characteristics of commercial amateur radio equipment with detailed measurements.
Results obtained from the most common commercial transceivers indicated that efforts to reduce QRM caused by other stations operating in close proximity must, in the first instance; focus on cleaning up the transmitter of the neighboring station! Often, older equipment exhibit sideband noise characteristics that are superior to more modern design concepts. But optimizing one's own and others' stations requires a lot of experience and suitable test equipment. Also, components that are not at first sight recognized as critical, such as power supplies and ALC circuitry, need to be included in the analysis. Summarizing the results of his work, Wolf-Henning concluded laconically: "it's all junk!"
The transceivers that were tested, simply did not measure up to what could nowadays reasonably be expected and achieved through careful design practice. But Wolf-Henning did not stop there. He suggested specific measures to ameliorate the QRM problem and proposed to speak to transmitter characteristics more extensively next year.
Honouring his commitment at last year's conference, Roland Neumann, DL8DAV, underpinned the theory of the Smith Chart with some practical applications. He demonstrated how easy the chart is to use by working an example of determining the complex input and output impedances of an HF-transistor. Roland's intent was not to treat the topic exhaustively but rather to encourage delegates to explore the subject further themselves. He undertook to publish a more comprehensive treatise of the topic for inclusion in the conference proceedings.
There followed a combination of papers on the subject of 'deep space communication', which will in years to come see increasing involvement by microwave amateurs as communication with future amateur satellites will be exclusively on microwave frequencies. Freddy de Guchteneire, ON6UG, covered the topic in three separate papers, beginning with an explanation of basic concepts for which he used the AMSAT-DVD.
During the lunch break delegates had to take an 'executive decision' to choose between food or a live demonstration of satellite reception at 8.4 GHz. For this purpose Freddy had brought along his portable receiving station, consisting of a one-meter dish with an integrated GHz converter followed by a tunable IF. Freddy intended to receive signals from MarsRO, then at a distance of 182 million kilometers from Earth, with this open-air setup. Unfortunately, weather conditions frustrated these efforts. Dense rain clouds caused excessive attenuation and reduced reception to barely a trace of MarsRO's signal. Although somewhat disappointing, the many interested listeners were not too bothered, given that the important technical challenge of receiving a weak microwave signal had been met.
Following this demonstration Freddy spoke to the future AMSAT amateur satellites P3E, P5A and the receiving station at the Bochum observatory. In addition to the technical details of these satellites, the scheduled operating frequencies were announced. Delegates were pleased to learn that transponders at 24 GHz and 47 GHz are to be included in P3E.
After Freddy's lecture Kjeld Bülow Thomsen, OZ1FF, and Norbert Richter, DL1SUN examined the prospects of flatland microwave DXing. They showed that by exploiting all available propagation mechanisms, such as tropospheric effects, rain scatter, sea ducting and reflections from aircraft, and employing suitable operating techniques, it is possible to bridge extraordinary distances at microwave frequencies even in areas devoid of significant elevations.
In his second paper, Wolf-Henning Rech, DF9IC, focused on the now somewhat forgotten aircraft reflection propagation mode which has recently been rediscovered as a possible aid to long-distance communications, complementing raincloud and thundercloud reflection modes.
On the lower microwave bands at 1296 MHz and 2320 MHz, in particular, does this phenomenon open up the prospect of covering up to approximately 800 km even during unfavorable weather conditions. In addition to providing estimates of the achievable distances, Wolf-Henning gave advice on how to analyze such signals of often very short duration. The reception of so-called 'Mode-S' signals at 1090 MHz (coded in the ADS-B-Protocol), that are routinely transmitted by aircraft facilitates the planning of long-distance communications as opposed to relying on random contacts. Such analyses are now possible with the availability in Germany since mid-2005 of non-professional hardware called 'SBS-1' which enables tracking of aircraft on a PC. Wolf-Henning demonstrated the use of this tool in planning long distance contacts in great detail. He proposed to establish a net of receiving stations across central Europe which would feed the 'ADS-B' data to the Internet for correlation and dissemination to interested microwave amateurs. In this manner a large number of amateur stations would be able to utilize aircraft reflections for long distance communications without having to invest in the special ADS-B equipment. In his wrap-up, Wolf-Henning, using recorded audio signals and waterfall screen shots, illustrated a successful 23cm band contact over 777km (close to the reflection distance limit) with SK7MW which would not have been possible without the aid of the SBS-1 and careful planning.
As a special 'bonus' to close the technical session, and as promised at last year's conference, the organizers had arranged for a presentation of the 'microwave recipe' by Frank, DL2ALF with support from Harti, DL6AUI.
They showed that their long-running success in winning the contest was not down to witchcraft but rather the result of continuous improvement of technology and operating practices. They generously shared their know-how and suggested that success in contests has its roots both in strategic planning ahead of the event proper, as well as in a thorough 'post-mortem'. Video clips and audio recordings helped illustrate the atmosphere during the contest. In closing, the DL0GTH representatives stressed that their presentation should not deter, but rather encourage, other contest groups to strive to replicate their achievements.
In his closing remarks DJ6XV expressed his pleasure at not having to sermonize delegates for their active support as proved so necessary in the previous year. The many papers submitted as a result of that 'wake-up call' were proof that any discussion on whether or not to continue the conference in the future would indeed be pointless.
To the satisfaction of all present DL4BBU noted that during the course of the conference already some commitments had been obtained from OMs to present papers at next year's GHz conference. Additional he pointed out to use the homepage of the GHz conference (www.ghz-tagung.de) as a tool which will aid documenting the status of the preparations for the conference through the year.
As always, all lectures are summarized in the conference proceedings which is available at the cost price of 6, - € plus postage. Please order directly from DJ6XV. Also back issues of previous years' proceedings are still available.
Heinrich, DC6CF, participant in all 29 conferences (!), has produced videos/DVD of the conference again this year. Prospective customers should contact him please directly: Heinrich Frerichs, DC6CF, Süderstr. 12, D-26835 Holtland.
last Update: 04-22-2006