HAMNET Report 5th June 2022

The ARRL Newsletter, and GDACS said that, on Saturday, May 28, as Hurricane Agatha (the first hurricane of the eastern Pacific hurricane season) was ready to make landfall in Mexico, operators at WX4NHC at the National Hurricane Centre (NHC) were conducting the annual readiness check of the station for 2022.

This year marks the 42nd year of volunteer communication services for the NHC. After 2 years of volunteer ham radio operators working remotely from their home stations due to COVID-19 safety restrictions, hams were able to operate inside the NHC for this year’s annual test event.

The event was reported as successful, with all of the station’s radios and antennas having performed well. Within 8 hours, 289 contacts were made nationwide and internationally. Operators used HF, VHF, and UHF radios, as well as digital modes.

Then, on Monday, May 30, Hurricane Agatha hit Oaxaca, Mexico as a Category 2 storm, with maximum sustained winds of 170km/h. It was recorded as the strongest hurricane to come ashore in May during the eastern Pacific hurricane season, making landfall on a sparsely populated stretch of small beach towns and fishing villages in southern Mexico. The next morning, Agatha was downgraded to a tropical depression, with winds of 55km/h.

The Government of Oaxaca reports that at least nine people have died and 22 others are missing, mainly in the Coastal and Sierra Sur Regions of Oaxaca. Search and rescue operations are continuing. According to media, six fatalities and 10 missing people were reported in the municipality of Santiago Xanica which is one of the most affected areas, and the main route connecting the area has been destroyed. Many towns in Oaxaca are affected by power outages and roads blocked by landslides and floodwaters.

Greg G0DUB reports that Carlos CO2JC provided this update on Wednesday releasing the frequencies in use for Hurricane Agatha;

“The following frequencies that were used for communications due to the passage of Hurricane Agatha are released for the time being.

They are “7095 kHz, 7120 kHz, 3720 kHz and 14120 kHz.

“We continue to monitor the possible formation of a tropical cyclone in the area between the southwestern Gulf of Mexico and the north-western Caribbean Sea in the next few hours”, Carlos said.

Now here’s the first news of something that will become more and more useful and prominent in future radio comms.

Southgate Amateur Radio News reports that Paul Jaffe KJ4IKI and his team at U.S. Naval Research Laboratory have succeeded in transferring 1.6 kw of power over a 1 km path using 10 GHz

The US Navy describes it as being “the most significant power beaming demonstration in nearly 50 years.”

The aim was to demonstrate power beaming of 1 kW of electrical power over a distance of 1 km using 10 GHz. The two sites used were the U.S. Army Research Field at Blossom Point in Maryland, and The Haystack Ultrawideband Satellite Imaging Radar (HUSIR) transmitter at the Massachusetts Institute of Technology (MIT).

“The reason for setting those targets is to push this technology farther than has been demonstrated before,” said Paul Jaffe Ph.D., Power Beaming and Space Solar Lead. “You don’t want to use too high a frequency as it can start losing power to the atmosphere. 10 GHz is a great choice because the component technology out there is cheap and mature. Even in heavy rainfall, loss of power is less than five percent.”

In Maryland, the team exceeded their target by 60 percent by beaming 1.6 kW just over 1 km. At the Massachusetts site, the team did not have the same peak power, but the average power was much higher thereby delivering more energy. Jaffe said these demonstrations pave the way for power beaming on Earth, in space, and from space to Earth using power densities within safety limits set by international standards bodies.

“As engineers, we develop systems that will not exceed those safety limits,” Jaffe said. “That means it’s safe for birds, animals, and people.”

I predict that this technology will get incorporated into more and more power distribution systems for equipment at sites where no wired electricity is available.

Interesting Engineering has an article on Zombie Satellites still in orbit after decades of non-use, which have been found still to be transmitting beacon material or telemetry.

They include:

  • LES-1 a communications satellite from 1965, which spontaneously began to resume transmissions in 2012. Apparently, a short had developed in the satellite’s systems allowing power from the solar cells to reach the transmitter directly.
  • LES-5 a similar satellite launched in 1967, which revived itself from a graveyard orbit, and is still transmitting its telemetry beacon on 236.75MHz.
  • Transit 5B-5, launched in 1964, which can still transmit at 136.650MHz when it is passing through sunlight.
  • The most well-known to us is AMSAT-OSCAR 7, the second so-called “Phase 2” satellite designed and built by the Radio Amateur Satellite Corporation, or AMSAT for short. Launched into orbit in November of 1974, the satellite worked as expected for many years until its batteries finally died in mid-1981.

AO-7 carries two amateur radio transponders. The first, its “Mode A” transponder, has an uplink on the 2-meter band and a downlink on the 10-meter band. The second called its “Mode B” transponder, has an uplink on the 70-centimeter band and a downlink on the 2-meter band. AO-7 also carries beacons which are designed to operate on the 10-meter, 2-meter, and 70-centimeter band.

Miraculously, after several decades of silence, the satellite began to resume transmissions in June of 2002. The reason appears to be the fact that one of its batteries shorted, allowing it to become an open circuit and allow the spacecraft to run off its solar panels when the satellite is in direct sunlight.

Today, AO-7 is officially one of the oldest remaining communications satellites in existence. It will be 50 years old in 2024.

  • Others include Prospero (1971), Calsphere 1 and 2 (1964), Lageos-1 (1976) and ISEE-3, the latter orbiting the sun since 1978, hopefully to be reactivated in the future.

So folks, because we are old and decrepit, does not necessarily mean we have stopped being useful. Hopefully the older radio amateurs will continue to be mentors to the new licensees. No question that is ever asked, or piece of advice sought, is ever stupid. Sometimes, the answers are!

This is Dave Reece ZS1DFR reporting for HAMNET in South Africa.