Hier kun je geheel gratis de studiegids downloaden, uitgegeven door de IRTS:
When you think of directional ham radio antennas, you probably think of a Yagi, cubical quad, or a log-periodic antenna. These antennas usually are in a horizontal configuration up on a high tower. However, it is possible to build beams with a vertical orientation and, for some lower frequencies, it is far more practical than mounting the elements on a boom. [DXCommander] shows us his 40 meter two-element vertical antenna build in the video below.
A typical Yagi is just a dipole with some slightly longer or shorter elements to direct or reflect the signal. A normal vertical, however, is nothing more than half of a dipole that uses the ground as the other half. So it is possible to create reflectors and directors with a vertical-driven element.
The exact lengths and the spacing are critical and may require a bit of experimentation. [Callum] has another video (below the first one) that explains the design and math behind it. We’ve also seen arrays that require multiple elements driven out of phase to get similar effects. Of course, that requires exact lengths of cables and, in general, more cable, too.
One of amateur radio’s many interests comes in portable operation, taking your radio to an out of the way place, usually a summit, and working the world using only what can be carried in. Often this means using the HF or shortwave bands, but the higher frequencies get a look-in as well. A smaller antenna is no less the challenge when it comes to designing one that can be carried though, and [Thomas Witherspoon] demonstrates this with a foldable loop antenna for the 2 metre band.
The antenna provides a reminder that the higher bands are nothing to be scared of in construction terms, it uses a BNC-to-4 mm socket adapter as its feedpoint, and makes the rectangular shape of the loop with pieces of fiberglass tube. The wire itself is flexible antenna wire, though we’re guessing almost any conductor could be used. The result is a basic but useful antenna that certainly packs down to a very small size, and we can see it would be a useful addition to any portable operator’s arsenal.
If you’re a 2 metre band user, this certainly isn’t the first time we’ve visited lightweight antennas for this band.
For those of us who lived through the Cold War, there’s still an air of mystery as to what it was like on the Communist side. As Uncle Sam’s F-111s cruised slowly in to land above our heads in our sleepy Oxfordshire village it was at the same time very real and immediate, yet also distant. Other than being told how fortunate we were to be capitalists while those on the communist side lived lives of mindless drudgery under their authoritarian boot heel, we knew nothing of the people on the other side of the Wall, and God knows what they were told about us. It’s thus interesting on more than one level to find a promotional film from the mid 1970s showcasing VEB Fernsehgerätewerk Stassfurt (German, Anglophones will need to enable subtitle translation), the factory which produced televisions for East Germans. It provides a pretty comprehensive look at how a 1970s TV set was made, gives us a gateway into the East German consumer electronics business as a whole, and a chance to see how the East Germany preferred to see itself.
The sets in question are not too dissimilar to those you would have found from comparable west European manufacturers in the same period, though maybe a few things such as the use of a tube output stage and the lack of integrated circuits hints at their being a few years behind the latest from the likes of Philips or ITT by 1975. The circuit boards are assembled onto a metal chassis which would have probably been “live” as the set would have derived its power supply by rectifying the mains directly, and we follow the production chain as they are thoroughly checked, aligned, and tested. This plant produces both colour and back-and-white receivers, and since most of what we see appears to be from the black-and-white production we’re guessing that here’s the main difference between East and West’s TV consumers in the mid ’70s.
The film is at pains to talk about the factory as a part of the idealised community of a socialist state, and we’re given a tour of the workers’ facilities to a backdrop of some choice pieces of music. References to the collective and some of the Communist apparatus abound, and finally we’re shown the factory’s Order of Karl Marx. As far as it goes then we Westerners finally get to see the lives of each genosse, but only through an authorised lens.
The TVs made at Stassfurt were sold under the RFT East German technology combine brand, and the factory continued in operation through the period of German re-unification. Given that many former East German businesses collapsed with the fall of the Wall, and that the European consumer electronics industry all but imploded in the period following the 1990s then, it’s something of a surprise to find that it survives today, albeit in a much reduced form. The plant is now owned by the German company TechniSat, and manufactures the latest-spec digital TVs. Meanwhile for those interested in history there’s a museum exhibition in the town (German language, Google Translate link), which looks very much worth a visit should you be motoring across Germany.
As degenerate capitalists we weren’t offered the privilege of buying a TV from the Worker’s Paradise, so we never had the opportunity to see how their quality stacked up to that of the Western models. It’s worth remembering that however rose-tinted our view of the 1970s may be, British-made sets of the period weren’t particularly reliable themselves.
As a juxtaposition of how a communist TV factory saw itself, have a watch of a capitalist one doing a bit of self-promotion.
The Fly Your Satellite! (FYS) programme, initiated by the European Space Agency (ESA), presents an exciting challenge for radio amateurs and space enthusiasts worldwide to establish communication via the LEDSAT CubeSat digipeater. This unique opportunity invites participants to connect with the ESA Education Office ESTEC Ground Station in the Netherlands through the satellite digipeater, with a chance to win a special prize – a custom QSL card issued by the ESA Education Office and the LEDSAT team. Running from June 26 to July 30, this challenge offers an exciting chance for radio enthusiasts to engage with space technology and demonstrate their communication skills.
LEDSAT: An Overview
Developed by students at Sapienza University in Rome, LEDSAT is an educational 1U CubeSat that participated in the second edition of the Fly Your Satellite! programme. Its primary objective is to demonstrate a LED-based payload for ground-based optical tracking. The successful launch of LEDSAT on Vega flight VV19 on August 17, 2021, marked a significant milestone for the project. Upon launch, a competition for radio and space enthusiasts from all around the world was launched, encouraging participants to record the first signs of life of the spacecraft.
The Digipeater Challenge in Detail
The LEDSAT digipeater is a special feature capable of storing and retransmitting digital messages sent via UHF, serving as a transponder for long-distance communication. Messages can be retransmitted immediately or with an optional delay of up to two days.
To participate in the competition, radio amateurs are invited to send a message using the UHF band addressed to the ESA Education Office ESTEC Ground Station, with the callsign PI9ESA. The digipeater will be activated during specific time windows (see below), and operators involved in the project will be available at the station, “listening” for incoming messages.
Once a message is received successfully, the sender’s callsign and contact details will be recorded on a customised QSL card, providing recognition for their achievement. LEDSAT follows a Sun-Synchronous orbit, resulting in two communication windows each day – around midday and midnight – where it is possible to establish contact. To predict passes precisely above the ESTEC ground station or your area of residence, refer to this link. Additionally, the latest Two-Line Elements for LEDSAT can be retrieved here.
Considering the monitoring and housekeeping requirements of LEDSAT, as well as the potential high demand from operators, the digipeater activation time slots will follow a pattern of one day ON and one day OFF, with the switch-on/off always occurring at 00:00 UTC. This schedule will commence on Monday, June 26th 00:00 UTC, and conclude on Sunday, July 30th at 24:00 UTC.
While the challenge is supported by our operators on a voluntary basis, efforts will be made to cover as many LEDSAT passes as possible, especially those occurring around local midday on weekdays. A detailed schedule of passes coverage will be published, please make sure to check this article regularly for updates.
Specific Time Slots for LEDSAT Digipeater Activation
Please note that this schedule may be subject to change, so stay updated on any revisions by referring back to this article or additional information provided by the FYS programme organisers on the ESA Education social media channels.
The LEDSAT team has prepared a software package for connecting to the digipeater, along with a user manual available for download on the LEDSAT website. Specific parameters are required to communicate with the LEDSAT digipeater (see table).
Parameters for LEDSAT Digipeater Communication
|LEDSAT TX frequency (uplink)
|LEDSAT RX frequency (downlink)
|CSP + Golay + ASM (AX100 Mode 5)
Important note: If you are not a licensed radio amateur, transmitting to the satellite is prohibited. Nevertheless, you can still participate in the challenge by listening to the messages transmitted by the ESTEC ground station. If you provide evidence of successful reception, including the date and time, you may also receive a customised QSL card.
So, mark your calendars, prepare your messages, and don’t miss your chance to connect and communicate with the LEDSAT spacecraft to receive your QSL card. Let’s unite and make this event a memorable celebration of our shared passion for space exploration and amateur radio communication.
For any questions regarding LEDSAT or the digigpeater challenge, please email firstname.lastname@example.org.
[NASA] and a team of partners has demonstrated a space-to-ground laser communication system operating at a record breaking 200 gigabit per second (Gbps) data rate. The TeraByte InfraRed Delivery (TBIRD) satellite payload was designed and built by [MIT Lincoln Laboratory]. The record of the highest data rate ever achieved by a space-to-Earth optical communication link surpasses the 100 Gbps record set by the same team in June 2022.
TBIRD makes passes over an ground station having a duration of about six-minutes. During that period, multiple terabytes of data can be downlinked. Each terabyte contains the equivalent of about 500 hours of high-definition video. The TBIRD communication system transmits information using modulated laser light waves. Traditionally, radio waves have been the medium of choice for space communications. Radio waves transmit data through space using similar circuits and systems to those employed by terrestrial radio systems such as WiFi, broadcast radio, and cellular telephony. Optical communication systems can generally achieve higher data rates, lower loses, and operate with higher efficiency than radio frequency systems.
TBIRD is a 3U sized satellite payload, meaning it is approximately the size of box of tissues. The TBIRD payload is carried aboard NASA’s Pathfinder Technology Demonstrator 3 (PTD-3) satellite. PTD-3 is a CubeSat measuring about the size of two cereal boxes stacked together. The satellite is synchronized to the Earth’s orbit around the Sun such that it passes over the same ground station at the same times, twice each day.
Achieving the record breaking TBIRD data transmissions truly takes a village. The TBIRD space payload was designed and built by [MIT Lincoln Laboratory]. The payload flies aboard the PTD-3 satellite built and operated by [Terran Orbital]. The PTD-3 satellite was carried into orbit by a [SpaceX] Transporter-5 rideshare mission launched from the [NASA Kennedy Space Center]. The TBIRD mission and concept was developed at the [NASA Goddard Space Flight Center] while the PTD-3 program and mission is managed by the [NASA Ames Research Center]. Finally, the ground station for the data link is part of the Optical Communications Test Laboratory at the [NASA Jet Propulsion Lab].
Of course, future space missions can embed the record breaking optical communication technology demonstrated by TBIRD. Downlinking massive amounts of data from space to Earth is imperative to evolving scientific missions. For example, we expect to enjoy live 4K ultra-high-definition video streaming from the Moon thanks to the Orion Artemis II Optical Communications System (O2O).
Bij onze vrienden van Van Cranenbroek krijg je allerlei gerei om je weiland met schrikdraad af te zetten. Tussen al dat moois bevindt zich één artikel dat specifiek voor de draadantenne bijzonder geschikt is.
Deze isolator is overigens een slechte isolator want beide kanten zijn met elkaar verbonden middels een veer maar juist dat laatste maakt dit een ideaal tussenstuk voor je draadantenne: door deze achter de isolator te plaatsen, kun je de antenne op spanning ophangen maar heeft de antenne de gelegenheid om in de veer heen en weer te bewegen. De veer is behoorlijk stug maar flexibel genoeg om bij een botsing met een vogel op te rekken en terug te veren.
In de foto zie je nog een vogel langsscheren, die had geluk. Maar je ziet ook dat de haak aan de rechterzijde nog open is, die moet gesloten worden door deze in de bankschroef in te klemmen en dicht te buigen.
Vergeet er dus geen echte isolator tussen te zetten, anders maakt deze veer deel uit van je antenne (tenzij je dat wilt).
Er is nog meer leuks bij Van Cranenbroek, zoals lange veren waarmee je tussen schrikdraad een soort hekwerk kunt maken, die kunnen ook prima dienen om een draadantenne op te spannen en ze hebben nog een leuk haspeltje voor draad, als je tijdens een velddag wat wilt klooien.
Enfin, het is weer knutselweer!
Trivia: What does “Roger that” mean and what’s the origin?!
ANSWER: Roger that or usually simply Roger is a phrase used in the military to confirm that a message has been received and understood.
In the 1940s, the American military and British RAF used a spelling alphabet different from the current well-known Alfa, Bravo, Charlie of today.
The letter “R” was used as an abbreviation for “received” back in the day when messages were sent via telegraphy (in Morse code), and the practice of confirming that a transmission was received by sending an “R” back was extended to spoken radio communication at the two-way radio became popular during World War II.
The phonetic alphabet used by the British and American military during the World War II was:
Able, Baker, Charlie, Dog, Easy, Fox, George, How, Item, Jig, King, Love, Mike, Nan, Oboe, Peter, Queen, Roger, Sugar, Tare, Uncle, Victor, William, X-ray, Yoke, Zebra.
When a Soldier or a Sailor, radio operator said “Roger” after receiving a transmission, he was simply saying “R” for “received”.
The phonetic alphabet has changed since then, but the practice of replying to a message by saying “Roger” stuck.
It is just a coincidence that two-way radio became widespread during the relatively short period when the phonetic name of the letter “R” was “Roger”.
Before 1940, it used to be “Robert”, and from 1956 on, it has been Romeo.
73 de Jeff N7TBU