Microwave data application in Dubus Magazine

Dubus is a quarterly magazine for technology, construction, DX and propagation on VHF/UHF and Microwave bands. It is edited in English and German languages by an international group of hams, printed in Germany.

I have blogged a few times before, on how the amateur microwave bands are so seldom used, and are our greatest allocation, as well as potential area for new development.

The problem is for the most part, the microwave bands sit idle, except for a few contests a year. Dubus is mostly what you'd expect, hams building microwave stations for the quest of a contact record.

I have never been that type, to each their own.

I am more interested in building infrastructure or something a number of hams can use. Which is why I like data networks, as I feel it can support a variety of applications while keeping some constant use of the frequencies.

Dubus 4/2006 - Microwave Japan Seiji Fukushima, PH.D, JH6RTO

High-speed IP connection on 5760 MHz by Hiroyuki, JH1UGF and Tsugno, JN1AYV

We report a 63 km high-speed IP connection on 5760MHz using ICOM ID-1's and modified transverters, UTV5600BIIP. The throughput was measured as about 100 kb/s at the application of layer .

Here are the details.

On the 29th of October, 2006, Hiroyuki, JH1UGF moved to Mt. Toogasa (altitude about 900 metres) and Tsugno, JN1AYV stayed at home in Chagasaki, Kanagawa for this experiment. The distance was 63km and both of us were within the line-of-sight. We used the same systems as follows. Our 1295MHz, digital transceiver was ICOM's ID-1 . To up/down-convert frequency, the 5760MHz transverters UTV5600BIIP were employed but some circuits were modified for this experiment. Since fast T/R switching is quite important, we removed the coaxial relay and added a circulator instead, as shown in Fig.1. In addition, two anti-parallel diodes were Inserted at the RX front end in order not to damage the preamplifier. These diodes cannot be seen In Fig, 1 unfortunately . The driver amplifier is MGF0904A and the final amplifier is 2xMGF1302, which outputs about 1W. We used a homebrew 25cm dish antenna with a horn radiator. Its gain was 25dBi.

We started our experiment. The voice QSO on FM was quite successful, RS 59+, as the distance was short enough . Then, we switched to direct digital mode for IP connection but the result was poor . Using a ping command of MS-DOS, Its connection rate was lower than 10%. Considering the multipath effect, we changed the frequency and/or antenna direction, but in vain. Lastly, Tsuguo moved his entire system , which was initially set in his room, to a balcony. Tsuguo had thought the experiment would have been successful even through a glass window since they had been within the line-of-sight. We got 100% ping connection after this trial.

Then we tried an application experiment. Using IP Messenger (IPmsg) software, Hiroyuki loaded an Tsuguo's image file into the Hiroyuki's PC. Look at our evidence of Fig. 2. The front is Hiroyuki and the back is Tusguo in the inset photograph. The 90KB file transfer took 6 or 7 seconds and, then, its application-layer throughput was calculated to be approximately 100kb/s . We learned that any thin obstacle in the path might make the multi-path interference at high-speed data communication. We would like to make the distance longer and to make the throughput higher in future.

What I did pay attention to in this article was that for the fast T/R switching they used circulators. I am not sure why this never occurred to me. I noticed this concept in 2006 Microwave Technology Letter, titled "Switchless Bidirectional Amplifier For Wireless Communication Systems."

So far this is the only microwave data application I have read in Dubus. I find that a bit odd, as there is a huge microwave data radio network in Germany and Europe.

If anyone else knows of good reading in these areas, I'd appreciate a note.

Microwave Projects =/ ARRL

It was very sad to read the passing of John Champa, K8OCL. He was former Chairman of the ARRL HSMM (High Speed Multimedia) Working Group. He was also the High Speed Multi-Media Radio Contributing Editor for CQ VHF Magazine.

Unlike most hams he had a high level of energy and ambition for his work on HSMM and in other areas of the hobby not well explored.

I am beginning to sound like Wayne Green with my ARRL critical comments.

But hey, they led me on, to think there was some sort of Microwave Bandplan changes in the midst. Truth is, I am not sure of the status if this, and can't get any real answers from the league.

Regardless if these jokers want to live in the past or not, here is an interesting thing to consider:

Amateur Allocations - Little known fact

Did you know in the US amateurs have access to approximately:
3.75 MHz of HF (160m-10m) spectrum
67 MHz of VHF/UHF (6m-33cm) spectrum
24.095 GHz of microwave (23cm-300GHz) spectrum

Of the above, over 99% of hams use a tiny fraction (0.3%) of the total ham frequency allocations while the remainder of our available ham allocation is essentially ignored. By the way, ARRL said that as of 4/2010, there were about 688,500 personal ham radio licenses in the USA. If only one percent of these were microwave users, that would be 6885 hams. We often hear that the majority of licensed hams are inactive. How many microwave experimenters do you know?

Source: hsmm-mesh.org

The realization occurred I was just a Technician over 10 years ago was that wow, there is a lot to explore and learn in the Microwave arena.

Since then I have learned a lot and found it absolutely critical to have that under your belt.

I remember reading the HSMM partnership with the North Texas Microwave Society when John, K8OCL moved to Texas. And have to concur that is a great idea.

Since the ARRL has been so quiet, I have decided I need to do the same. But I will be supplementing my blog space with more technical microwave experimentation articles in hopes of helping spur others on.

Since the mid-90's when I got into the hobby I have been connected to a then- high-school technology club. Ever since the same basic group of now 30's aged guys get together to shoot-the-shit, complain about the ARRL :-) and most importantly see what we can build.

What you will notice from my future blogs is that there have been few HF related projects, and many microwave. As it should be.

It's a shame the ARRL doesn't understand simple math. There is far more to lose in our microwave spectrum than HF. Because there is tons more of it, and hardly any hams use it, and the commercial squatters actually see it as useful spectrum.

Hmm, if only we could do more than throw money to protect spectrum. Perhaps the following microwave projects could be QST material to help foster so actual use? Naa.. that is right we don't want to make anyone smarter. I am a believer that if ham radio is to evolve, then QST needs to. The concept that QST needs to continued to be watered down just doesn't stick with me.

The Proposed NTIA "Fast Track" Spectrum Reallocation shows that our 2.3 and 3 GHz allocations may be endanger. So to start off here is a 4 watt power amplifier for 2 GHz.