Is That Antenna Allowed? The Real Deal On The FCCs OTARD Rule

August 30, 2024 by Dan Maloney 80 Comments

The Hackaday comments section is generally a lively place. At its best, it’s an endless wellspring of the combined engineering wisdom of millions of readers which serves to advance the state of the art in hardware hacking for all. At its worst — well, let’s just say that at least it’s not the YouTube comments section.

Unfortunately, there’s also a space between the best and the worst where things can be a bit confusing. A case in point is [Bryan Cockfield]’s recent article on a stealth antenna designed to skirt restrictions placed upon an amateur radio operator by the homeowners’ association (HOA) governing his neighborhood.

Putting aside the general griping about the legal and moral hazards of living under an HOA, as well as the weirdly irrelevant side-quest into the relative combustibility of EVs and ICE cars, there appeared to be a persistent misapprehension about the reality of the US Federal Communications Commission’s “Over-the-Air Reception Devices” rules. Reader [Gamma Raymond] beseeched us to clarify the rules, lest misinformation lead any of our readers into the unforgiving clutches of the “golf cart people” who seem to run many HOAs.

According to the FCC’s own OTARD explainer, the rules of 47 CFR § 1.400 are intended only to prevent “governmental and nongovernmental restrictions on viewers’ ability to receive video programming signals” (emphasis added) from three distinct classes of service: direct satellite broadcasters, broadband radio service providers, and television broadcast services.

Specifically, OTARD prevents restrictions on the installation, maintenance, or use of antennas for these services within limits, such as dish antennas having to be less than a meter in diameter (except in Alaska, where dishes can be any size, because it’s Alaska) and restrictions on where antennas can be placed, for example common areas (such as condominium roofs) versus patios and balconies which are designated as for the exclusive use of a tenant or owner. But importantly, that’s it. There are no carve-outs, either explicit or implied, for any other kind of antennas — amateur radio, scanners, CB, WiFi, Meshtastic, whatever. If it’s not about getting TV into your house in some way, shape, or form, it’s not covered by OTARD.

It goes without saying that we are not lawyers, and this is not to be construed as legal advice. If you want to put a 40′ tower with a giant beam antenna on your condo balcony and take on your HOA by stretching the rules and claiming that slow-scan TV is a “video service,” you’re on your own. But a plain reading of OTARD makes it clear to us what is and is not allowed, and we’re sorry to say there’s no quarter for radio hobbyists in the rules. This just means you’re going to need to be clever about your antennas. Or, you know — move.

A Simple But Effective Receiving Loop Antenna

August 25, 2024 by Jenny List 21 Comments

There’s a joke in the world of radio that all you need for a HF antenna is a piece of wet string, but the truth is that rudimentary antennas rarely perform well. Random pieces of wire may pull in some signal, but along with it comes a ton of unwanted interference and noise. It’s thus worth putting in the effort to make a better antenna, and if you’re not fortunate enough to have a lot of space, your best choice may be a magnetic loop. [Robert Hart] takes us through the design of a receive-only coaxial loop. It’s referred to as a Moebius loop because the conductor takes a “twist” path between the inner and outer halfway around.

The idea of a loop antenna is simple enough. It’s an inductor intended to respond to the magnetic portion of the wave rather than the electric part. They’re normally made of a single turn of wire in a loop of diameter well below half a wavelength, and, in their transmitting versions, they are often tuned to resonance by an air-spaced variable capacitor. Coaxial loops like this one provide enhanced resistance to electrical noise. He’s using some rather expensive Andrews coax for its rigidity, but the less well-heeled can use cheaper stuff without penalty. The result, when put on a frame of PVC pipe and a speaker stand, is an excellent portable receiving antenna, and if we’re being honest, something we might also consider in our own shack.

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An Antenna To Throw You For A Loop

July 29, 2024 by Al Williams 27 Comments

It is one of Murphy’s laws, we think, that you can’t get great things when you need them. Back in the heyday of shortwave broadcasting, any of us would have given a week’s pay for even a low-end receiver today. Digital display? Memory? Digital filtering? These days, you have radios, and they aren’t terribly expensive, but there isn’t much to listen to. Making matters worse, it isn’t easy these days to string wires around in your neighborhood for a variety of reasons. Maybe you don’t have a yard, or you have deed restrictions, or your yard lacks suitable space or locations. This problem is so common that there are a crop of indoor antennas that seem attractive. Since I don’t often tune in shortwave and I don’t want to have to reset my antenna after every storm, I decided to look at the Tecsun AN-48X along with a YouLoop clone from China. Let’s start with the Tecsun. Continue reading “An Antenna To Throw You For A Loop” →

You’ve Got The Portable Radio, Now What About The Antenna?

July 28, 2024 by Jenny List 10 Comments

There’s an old saying in the amateur radio community that when it comes to antennas all you need is a piece of wet string. This may be a little fanciful, but it’s certainly true that an effective antenna can be made with surprisingly little in the way of conductor. It’s something [Evan Pratten VZ3ZZA] demonstrates amply with a description of the antenna he took camping in a Canadian provincial park.

Most of us would try some form of dipole on our adventures, but the antenna he’s using caught our eye as it’s described as an end-fed half-wave, but it has both a half-wave and quarter-wave element. Made from speaker cable or in this case thin mains cable for lamps, it’s obviously far from a perfect match and requires an ATU, but it generates an impressive array of FT4 contacts on a pretty meagre power level. We particularly like his in-plain-sight test run in the parking lot of a supermarket.

We frequently talk about the diversity of pursuits in amateur radio aside from that of the chequebook ham, and this project shows one of those. The world of QRP, operating at extreme low power, is not expensive to enter and can be extremely rewarding.

Going Ham Mobile On A Bicycle

July 8, 2024 by Dan Maloney 19 Comments

It’s said that “Golf is a good walk spoiled,” so is attaching an amateur radio to a bike a formula for spoiling a nice ride?

Not according to [Wesley Pidhaychuk (VA5MUD)], a Canadian ham who tricked out his bike with a transceiver and all the accessories needed to work the HF bands while peddling along. The radio is a Yaesu FT-891, a workhorse mobile rig covering everything from the 160-meter band to 6 meters. [Wes] used some specialized brackets to mount the radio’s remote control head to the handlebars, along with an iPad for logging and a phone holder for streaming. The radio plus a LiFePO₄ battery live in a bag on the parcel rack in back. The antenna is a Ham Stick mounted to a mirror bracket attached to the parcel rack; we’d have thought the relatively small bike frame would make a poor counterpoise for the antenna, but it seems to work fine — well enough for [Wes] to work some pretty long contacts while pedaling around Saskatoon, including hams in California and Iowa.

The prize contact, though, was with [WA7FLY], another mobile operator whose ride is even more unique: a 737 flying over Yuma, Arizona. We always knew commercial jets have HF rigs, but it never occurred to us that a pilot who’s also a ham might while away the autopilot hours working the bands from 30,000 feet. It makes sense, though; after all, if truckers do it, why not pilots?

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VHF/UHF Antennas, The Bad, The Ugly, And The Even Worse

July 3, 2024 by Al Williams 69 Comments

When you buy a cheap ham radio handy-talkie, you usually get a little “rubber ducky” antenna with it. You can also buy many replacement ones that are at least longer. But how good are they? [Learnelectronics] wanted to know, too, so he broke out his NanoVNA and found out that they were all bad, although some were worse than others. You can see the results in the — sometimes fuzzy — video below.

Of course, bad is in the eye of the beholder and you probably suspected that most of them weren’t super great, but they do seem especially bad. So much so, that, at first, he suspected he was doing something wrong. The SWR was high all across the bands the antennas targeted.

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DIY Passive Radar System Verifies ADS-B Transmissions

April 29, 2024 by Bryan Cockfield 5 Comments

Like most waves in the electromagnetic spectrum, radio waves tend to bounce off of various objects. This can be frustrating to anyone trying to use something like a GMRS or LoRa radio in a dense city, for example, but these reflections can also be exploited for productive use as well, most famously by radar. Radar has plenty of applications such as weather forecasting and various military uses. With some software-defined radio tools, it’s also possible to use radar for tracking aircraft in real-time at home like this DIY radar system.

Unlike active radar systems which use a specific radio source to look for reflections, this system is a passive radar system that uses radio waves already present in the environment to track objects. A reference antenna is used to listen to the target frequency, and in this installation, a nine-element Yagi antenna is configured to listen for reflections. The radio waves that each antenna hears are sent through a computer program that compares the two to identify the reflections of the reference radio signal heard by the Yagi.

Even though a system like this doesn’t include any high-powered active elements, it still takes a considerable chunk of computing resources and some skill to identify the data presented by the software. [Nathan] aka [30hours] gives a fairly thorough overview of the system which can even recognize helicopters from other types of aircraft, and also uses the ADS-B monitoring system as a sanity check. Radar can be used to monitor other vehicles as well, like this 24 GHz radar module found in some modern passenger vehicles.

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