Can Radio Amateurs use Transceiver Antenna Arrays  - Page 1
Forum section: electronics / rf-microwave

author: jonovid
author_rank: Super Contributor
timestamp: September 29, 2025, 09:16:55 am
content: array of multiple low power micro transceivers with antennas running in parallel all at the same time.single transceiver made up of multiple low power micro transceivers with antennas that work in parallel.radio telescopes use arrays when the size of a single large dish antenna is not practical.

author: LaserSteve
author_rank: Super Contributor
timestamp: September 29, 2025, 04:32:58 pm
content: For an antenna array the RF source(s) or receive local oscillator should / must be phase coherent, so in practice transmission RF power tends to come from a single source, although phase locking and distributed amplification is possible.Answer is Yes, we can. Yes, it has been done. Arrays are not a new thing, having been around since 1905 give or take. As long as we do not exceed the total output power or peak effective power on our license, at least in the US, in theory we're good to go. Other countries may have restrictions on ERP, i.e. effective radiated power, and that may be a different case.If you're talking about something like a very long baseline receive array, or long diversity reception schemes, you might have to ask which group got there first, and the answer might surprise you. Its a tossup between amateurs, telecom, military, marine radio companies and the overseas telephone companies prior to undersea cables proliferating.For example, here is a rather nice but rather expensive set of off the shelf four and eight element array phasing harness kit:https://www.dxengineering.com/search/brand/dx-engineering/department/antennas/section/hf-vertical-phased-arrays?srsltid=AfmBOorZy3oxK5b54zcADHi0JSD5jV_5-zrpo1TUpY5DquuOIOWYcmQEAmateur direction finding has long been array based, in 1990 I had a handheld, switched two element plus reflector DF rig at UHF/VHF, and that worked remarkably well using of all things 1n4001 as a poor man's PIN diode switch with a NE555 as the driver switching the antennas. It was published in several books and magazines at the time. Eventually the local TV repair parts place ordered me some actual NTE PIN diodes, which slightly improved the sensitivity. At the time it was known that some 4001 had a bit of an intrinsic layer as a guard ring or something. 1N914 worked as well.,Steve

author: jonovid
author_rank: Super Contributor
timestamp: September 29, 2025, 05:28:07 pm
content: collaborative projects work for students and low power micro transmitters could reduce radio interference while working as one big transmitter.if the phase of the micro transmitters is under the central control of a single operator with the other radio operators present at the same time.on the receiver side of the arrays. multiple receivers may just overcome radio noise floor level with central of the phase.collaborative projects also reduce costs by the modular design of radio equipment. pcb board assembly by students on a collaborative project.generation z like collaborative projects. traditionally Radio Amateurs are seen as solo operators.just a suggestion. if your hobby is in decline with generation z.

author: radiolistener
author_rank: Super Contributor
timestamp: September 30, 2025, 05:55:02 am
content: Just curious — who are you intending to communicate with using a transmission array like that? Aliens, perhaps?Also note that many countries limit power flux density and set maximum EIRP limits — attempting to bypass transmitter power caps by using many low‑power elements won't be legal everywhere. In practice enforcement may be lax, but relying on that is neither safe nor lawful.

author: LaserSteve
author_rank: Super Contributor
timestamp: September 30, 2025, 03:04:21 pm
content: When you dig into it, the better the antenna, the bigger the win. Adding transmit power beyond a certain point does not gain you anything, but concentrating that power with a good antenna or higher antenna, thus increasing the ERP, is more beneficial. Basically distributed or diversity receive is a winner under certain circumstances for certain bands, provided the receivers all have a very low noise figure, which can be expensive to achieve. Rather than using a true theoretical coherent distributed array, the receiver with the best signal to noise level (Called "Voting") is selected, and this has been used since the 1960s.Multi site coherent transmitting is/was used for paging at UHF and VHF and for radio dispatch in very, very large cities, and the transmitters have to match in frequency to a fraction of a Hertz. This was used for the "Urban Canyon" problem where propagation is very, very random. Cellular and Digital Trunked radio has made this somewhat obsolete.Where this falls apart is reciprocity, with the exception of propagation beacons, balloon telemetry, and in some cases packet data, amateurs are not in the broadcast business, we're expected to have a reciprocal path to the other participant of the conversation. Having a fixed distributed system without real-time steering is not meeting the spirit (and the rules) of international amateur radio. Oh, we do like QSL cards for those exotic one way shots, but again, not really the goal from a licensing and treaty perspective.A deceased friend used to have the record for a one way QSO on the 20 meter band, having hooked a 28 Mhz TTL clock oscillator to a curtain array, and they calculated the propagation path as "90% of the way around the world" with a few mW. That was 20 years ago.The more modern digital modes achieve wonderful "below the noise" performance with inexpensive coherent processing gear, as long as you have a PC to chew on the data and do the processing.So local arrays do well, massively distributed arrays are more for things like deep sound channel SONAR and seismic survey, and detecting certain types of explosions worldwide.A close case to what your talking about is forward and store, used in packet radio and APRS networks for a long, long, time. Many simple, tiny distributed nodes, trading off real time messaging for simplicity, with short messages at 110, 1200, 2400, 9600 baud, and in these days, add in internet gateways to cross the oceans.This kind of thing exists, even with meteor scatter or aircraft scatter as the relay means.I have papers describing using a local AM Radio or TV station for sync for multi-station spread spectrum communications, that fad went away quickly, once mass produced spread spectrum chipsets and GPS solved the sync problem by other means.Using a local AM radio station as a clock for distributed amateur PNT was done by clever folks using a version of the Synchronous Oscillator:https://wiki.jlab.org/ciswiki/images/8/88/Injection_locking_paper_2.pdfVasil Uzunoglu's circuit was quite a hit for about half a decade from VLF to UHF. There are plenty of papers and publications on it.Steve

author: TimFox
author_rank: Super Contributor
timestamp: September 30, 2025, 04:10:25 pm
content: Phased arrays of antennas exploit “constructive interference” to increase the received signal power, compared with simpler antennas.In radiation applications, interference does not increase or destroy power, but re-arranges it (increasing in some directions and decreasing in others).

author: fourfathom
author_rank: Super Contributor
timestamp: September 30, 2025, 04:43:20 pm
content: Distributed antenna arrays do well for transmit and receive beamforming, but for receive an array of small antennas / receivers will have a higher noise floor than a single equivalent-gain large antenna / receiver (assuming similar amplifier noise figures). This is why Arecibo could hear signals that array systems could not. But in many cases the advantages of a distributed system outweigh the disadvantages (I was involved with the Allen Telescope Array, which can simultaneously focus multiple beams by using post-detection DSP).I'm a huge fan of distributed receive and transmit systems, but not so much for the coherent applications. We're doing propagation research in the ham bands using transmitters and receivers distributed across the world, many of these GPS-disciplined, and having a large number of simultaneous paths and frequencies can tell us a lot about what's happening in the ionosphere.Coherent beamforming gets to be a problem when the sites are placed so far apart that the variations in ionospheric propagation delay become a factor. I assume that this can be calibrated out by using reference signals, but I'm not aware of this being done in the HF bands (or any ham bands). Ionospheric propagation can change very rapidly -- the "flutter" you can hear on distant signals is due to fast delay and polarization changes.