Thanks a lot 🙏

Well, in fact this is just a very good but "short" video scratching the surface of antenna and RF theories. If you are interested in that stuff, you can buy a lot of books dealing with details of one or few antenna types or some aspects of antennas, and there is a whole engineering branch of study, just dealing with antennas and RF. I would recommend books (or even sets of books) like the "ARRL Antenna Book for Radio Communications" or alike (depending on your preferred language). It is a very interesting and fascinating subject, that was much more interesting (and understandable) when radios were just analog devices with coils, capacitors and a few transistors, as you easily and directly could *hear* and *see* the direct resulting differences inbetween different solutions. Computerization of radio receivers and it's complexity did make that whole stuff a lot more "black-box"-like and unfortunately makes it much harder to understand what is going on. So for the start I would recommend you to first go for radio stations on AM bands (long wave, up to short wave radio stations) or FM Radio stations, as there you get direct feedback on how good your antenna is working. Absoluteley not like with digital signal types like DVB, DAB, phones (GSM and later), WiFi and so on, where your usual receiver in best case will have some sort of very rough signal quality indicator. A good accesory for a HackRF also might be the Portapack case/display, that will give you the tool of "waterfall diagrams" showing the signal strength (as opposed to the "signal quality" which only shows some informations about the signal-to-noise ratio).

Thanks! 🙏

Yes. Many people today don't have the life skills of how to formulate what's in their head into written language and search engine-optimized query. Many don't know what they even want lol

Thanks a lot 🙏

Thanks! 🙏

btw another great quality informative video! its a pleasure to watch.

There are many ways to make an antenna multi band. One way is to have more than one antenna in one, compacting several dipoles together. Another way is to have "traps" along the antenna, small passive filter circuits that cut off the antenna for signals of certain frequencies. Another way is to use bands that are multiples of each other, the ham radio bands are like this 2m, 4m, 6m, 10m, 20m, 40m - this way one antenna can be resonant on multiple bands. Another way, which is mostly common on the HF bands below 30 MHz, is to use an antenna matching circuit or antenna tuner. On HF there is more leeway to use non resonant antennas, as long as they are long antennas, but their impedance still needs to be matched to the radio. An antenna is like a load (think resistor) to the radio, and that load needs to be 50 ohms. If you have an end fed long wire or whip antenna, the impedance will be very high. A matching circuit such as a balun/unun, can bring down the impedance closer to the required 50 ohms. However even if you match the impedance with a tuner, it doesn't necessarily make the antenna good radiator - but it might be good enough. An antenna tuner can also do this, or work together with a matching circuit. Many radios for HF have built in antenna tuners. Also military radios are typically built to withstand high impedance mismatches, and can survive high SWR - unlike hobby radios. For every point I make in this video, there is a longer "well, actually.." answer ;)

Thanks and congrats 🎉

You're welcome!

For receiving you can get away with eyeballing a dipole or ground plane in some approximate area of a frequency. If you want to build more complicated antennas like a yagi, it’s beneficial to have the NanoVNA even just for receiving to check that your design is working out correctly.

Thanks!🙏 There are plenty of options for being pedantic as I’ve had to cut out a lot of details to not make the video too long for the beginners. I’m happy to have lots of great input as yours in the comments though 🙌

Some do and will throttle down the output if they detect a bad SWR. Some are just built more robustly and can take even a high amount of reflected power. But a lot aren't. It's all down to cost and most hobby radios expect you to know to check your SWR before transmitting 50-100 watts into an antenna. You get to buy the radio for a little less money or get other features instead.

​@@sn0renThanks for the fast reply! Today I became a little more intrigued by radio thanks to you

For some reason a full wave antenna is a really poor radiator when used for transmitting. I'm not sure of it's receiving capabilities. The mysterious theory of antennas crosses into physics which is a weird place.

@@sn0ren That's why I find it so fascinating, we think we have it all figured out and then the universe says "not so fast, I've got some more puzzles for you!"

What shipped antennas? It depends on what the seller decided to include and it should say so in the listing.

@@sn0ren The authentic ones come with a set of antennas. Even the knock off clones come with almost identical ones. It's okay I found a guy who tested the knock off ones (watch?v=QZSs7vfO5cg) I don't have a VNA so I can't test mine but I can at least know what general area the antennas are in, I'm a noob so knowing which one to put on for what was kinda what I was after, yet sadly HackRF content is either for the painfully new beginner or the pro, there's nothing in the middle for the little finnicky things. :D Thank you for the reply though, I appreciate it!

There is no such thing as a set of authentic antennas. Every seller has their own idea of what antennas to include and the listing says what frequencies they are suitable for - but as I said in the video they are, at best, only for listening in these frequency areas. For transmitting always use a known resonant antenna.

If you’ve blown the amp on your HackRF you can just turn it off. Everything else still works. You can also use an external LNA.

You can also desolder the amp and fix the circuit yourself if you know how to solder. The internet says it's easy and self explanatory.

Always a good idea to have the amp turned until you actually are in a situation where you need it. I haven't had a situation where I would need the transmit amp yet.

@@sn0ren WOW! sn0ren thanks for the reply.

Yes, provided the police still use analog radio in your area.

​@@sn0renNot anymore unfortunately. I just bought one of these because I'm interested in learning more, and there's a lot to learn here. I thought that SDR was able to receive digital broadcasts such as that.

It’s a thicker alu Portapack body that is sold by OpenSourceSDRLab

If these antennas have a plastic shroud over them you don't really know what's inside without disassembling them. A lot of antennas use the same default plastic shroud, but have very different lengths of metal inside them. Some can be coiled, some can be stacked dipoles for increased gain... and some can just be marketing adding a few extra dBi's in the text and hoping that no one is the wiser.

@@sn0ren Is there an official way to measure their strength?

It’s a bit tricky but you can use a field strength meter. But with WiFi it can be difficult to measure.