Perhaps the second most famous law in electronics after Ohm’s law is Moore’s law: the number of transistors that can be made on an integrated circuit doubles every two years or so. Since the physical size of chips remains roughly the same, this implies that the individual transistors become smaller over time. We’ve come to expect new generations of chips with a smaller feature size to come along at a regular pace, but what exactly is the point of making things smaller? And does smaller always mean better?
Smaller Size Means Better Performance
Over the past century, electronic engineering has improved massively. In the 1920s, a state-of-the-art AM radio contained several vacuum tubes, a few enormous inductors, capacitors and resistors, several dozen meters of wire to act as an antenna, and a big bank of batteries to power the whole thing. Today, you can listen to a dozen music streaming services on a device that fits in your pocket and can do a gazillion more things. But miniaturization is not just done for ease of carrying: it is absolutely necessary to achieve the performance we’ve come to expect of our devices today. Continue reading “Smaller Is Sometimes Better: Why Electronic Components Are So Tiny”
It sometimes seems as though antennas and RF design are portrayed as something of a Black Art, the exclusive preserve of an initiated group of RF mystics and beyond the reach of mere mortals. In fact though they have their difficult moments it’s possible to gain an understanding of the topic, and making that start is the subject of a video from [Andreas Spiess]. Entitled “How To Build A Good Antenna”, it uses the design and set-up of a simple quarter-wave groundplane antenna as a handle to introduce the viewer to the key topics.
What makes this video a good one is its focus on the practical rather than the theoretical. We get advice on connectors and antenna materials, and we’re introduced to the maths through online calculators rather than extensive formulae. Of course the full calculations are there to be learned by those with an interest, but for many constructors they can be somewhat daunting. We’re shown a NanoVNA as a useful tool in the antenna builder’s arsenal, one which gives a revolutionary window on performance compared to the trial-and-error of previous times. Even the ground plane gets the treatment, with its effect on impedance and gain explored and the emergence of its angle as a crucial factor in performance. We think this approach does an effective job of breaking the mystique surrounding antennas, and we hope it will encourage viewers to experiment further.
If your appetite has been whetted, how about taking a look at a Nano VNA in action?
Continue reading “What Makes A Good Antenna?”
If you want to listen to satellites, you have to be able to track them as they pass over the sky. When I first started tracking amateur satellites, computing the satellite’s location in the sky was a part of the challenge. Nowadays, that’s trivial. What’s left over are all the extremely important real-world details. Let’s take a look at a typical ham satellite tracking setup and see how it all ties together.
Rotators for Steering
The popularity of robotics, 3D printing, and CNC machines has resulted in a deluge of affordable electric motors and drivers. It’s hard to imagine that an electric motor for rotating an antenna would be anything special, but in fact, antenna rotators are non-trivial engineering designs. Most of the challenges are mechanical, not electrical — the antennas that they drive can be huge, have significant wind loading and rotational inertial, and just downright weigh a lot. A rotator design has to consider bearings, weather exposure, all kinds of loads, not just rotational. And usually a brake is required to keep the antenna pointed in windy conditions.
There’s been a 70-some year history of these mechanisms from back in the 1950s when Cornell Dubilier Electronics, the company you know as a capcacitor manufacturer, began making these rotators for television antennas in the 1950s. I was a little surprised to see that the rotator systems you can buy today are not very different from the ones we used in the 1980s, other than improved electronic controls. Continue reading “Tracking Satellites: The Nitty Gritty Details”
Dealing with an antenna is one of those topics we never feel like we know enough about. MIT had a live stream of [Dr. Kiersten Kerby-Patel] discussing antennas in a talk, sponsored by the ham radio club on campus. You can see the recording below.
The main assertion of the presentation is that everything is a dipole unless it is a loop. Although the professor probably deals with antennas at an extremely high theoretical level, she did a great job of keeping it aimed at ham radio operators.
Continue reading “Ham Antennas From MIT”
Our friend [Hunter Scott] gave a talk at a past Supercon about phased array antennas. He mentioned he was looking for collaborators to create an antenna with the SiBeam SB9210 chip. This is a specialized chip for WirelessHD, a more or less failed video streaming protocol, and it’s essentially an entire 60 GHz phased array on a chip with both transmit and receive capabilities. For $15, it seems like quite the bargain, and [Hunter] still wants to put the device to work.
The downside is that Lattice bought SiBeam and killed this chip — not surprising considering WirelessHD never really took off. However, [Hunter] says the chip was in some old smart TVs and laptops. If you can find replacement boards for those devices on the surplus market, you can get the chip and the supporting circuitry for a song.
Continue reading “A 60 GHz Phased Array”
AM broadcasting had a big problem, but usually only at night. During the day the AM signals had limited range, but at night they could travel across the country. With simple wire antennas, any two stations on the same frequency would interfere with each other. Because of this, the FCC required most radio stations to shut down or reduce power at night leaving just a handful of “clear channel” stations for nighttime programming. However, creating directional antennas allowed more stations to share channels and that’s the subject of a recent post by [John Schneider].
When it comes to antennas, ham radio operators often think bigger is better. After all, hams typically want to work stations far away, not some specific location. That’s not true in the commercial world, though. The big breakthrough that led to for example cell phones was the realization that making smaller antennas with lower power at higher frequencies would allow for reuse of channels. In those areas the focus is on making cells smaller and smaller to accommodate more people. You can think of AM broadcasting as using the same idea, except with relatively large cells.
Continue reading “The Power Of Directional Antennas”
Watch Justin McAllister’s presentation on simple antennas suitable for a zombie apocalypse and two things will happen: you’ll be reminded that everything antennas do is amazing, and their reputation for being a black magic art will fade dramatically. Justin really knows his stuff; there is no dangle-a-wire-and-hope-for-the-best in his examples. He demonstrates that it’s possible to communicate over remarkable distances with nothing more than an off-the-shelf radio, battery pack, and an antenna of simple design.
Continue reading “Justin McAllister’s Simple, Post-Apocalypse-Friendly Antennas”