s; most are limited to less than 1m. Even with aerial whip antennas

Wavelength varies from 2.7 to 3.4 metres. Just because that is the size of the wave doesn't meant that a good antenna has to be that size. A very good basic antenna is a 1/4 wave vertical, and we see them pretty often as telescopic antennas on radios and cars. A 1/4 wave FM broadcast antenna will perform excellently, and will be 68cm to 85cm in length. More modern cars have antennas printed into a window similar to a demister strip. They are actually NOT smaller, some can be quite larve, but also very stealth. But the point remains is that they are NOT small as you suggest. Much shorter antennas exist, but there is a gain penalty, and that penalty gets more extreme the smaller the antenna gets. I have such a small antenna on my car and it IS an issue. In physics nothing is free, yes, you can make an antenna small and still have it be resonant, but you'll pay a price on effective gain.

This is a problem that technology has not solved. Sure, clever designs have helped a little, but there is always a price to pay if you try to cheat the physics.

A compromised antenna can work in a very very stong signal area, but it will easily be the difference between a clear solid recieve and no recieve at all in a fringe area.

AM Broadcast is an example of this, with antennas sometimes 2 inches / 50mm long or even less and hidden inside the radio. Buy as a ham myself with a HF setup, even my HF setup, which is a poor compromise on MF broadcast gets me stations from all over Australia. That isn't going to happen with a regular AM receiver.

Ultimately, sure you can have a mobile with no external antenna receive FM broadcast... but only in a VERY VERY strong signal area, within a few miles of the transmitter, while a propper antenna will work at 10x the distance.

Given that the proposal requires a minor redesign of the cellphones to incorporate the broadcast receiving radio, adding a small antenna, or simply using the chassis of the phone as an antenna, would not only be possible but it should be fairly trivial to accommodate for. by no means am I saying it would be the worlds greatest FM antenna system, most certainly it would not be, but it should be sufficient to differentiate the signal from the noise

This would work at very short distance only, it really would be that limited. Would it be useful for the people in those short distances? Maybe. Buy while a regular ordinary transistor radio with a telescopic antenna would work 10-30x further away, comparing those 2 really shows how much of a compromise is going on.

The point I’m dancing around is software-defined radios. The big cost of SDRs is mainly regarding transmission, since they don’t put out a very strong signal This is true for any radio type ever, it's not an SDR specific thing. EVERY radio that puts out more than a few dbm needs some level of amplification. This is NOT and SDR specific thing. It might appear that way because fo how many affordable SDRs just come with a low output. This is just a normal Monday for any radio system from a $50 CB to a broadcast station, SDR or not.

SDR's are not magic. In fact they actually have some drawbacks compared to conventional designs with regards dynamic rage, over loading etc.. Pulling the 'SDR' card and not knowing this i think shows your lack of understanding of the topic (not trying to diss, just an observation). SDR's are a great tool, i have 4 of them in front of me as i type this, so I'm no stranger. Icom IC-705, Icom IC-7300, HackRF and an RTL-SDR. You could also maybe count the University of Twente webSDR i have open in another tab, and an MMDVM at a stretch to make it 6. http://websdr.ewi.utwente.nl:8901/

This is all exciting stuff... but none of it has revolutionised RF physics for human portable commodity radios, nor even come close to an adjacent technology that could be adopted / adapted.

My ~ AUD$1900 IC-705 can go from picking up stations all over the state of Victoria, Australia with it's non optimal antenna tuned for 146MHz, to picking up literally nothing if i hook up a few hundred mm of wire to it's antenna socket on the bench here. And I can engage pass band filtering, up to 2 pre-amp stages, and a variety of Digital Signal Processing features and sill get... nothing.

I appreciate your passiona nd interest, but.... physics.

We can look at other technologies that are great... WiFi.. it's great, but the transmitter location is in your home and still struggles to cover some larger homes... from inside your home itself. Cellular.. again, great, but again, as the name implies it;s made up of 'cells', physics is a massive issue with cellular, each individual cell tower consists of tens or sometimes hundreds of transceivers, each connected to phased arrays of hundreds to thousands of antenna elements... and that's just a single site, many towns will need multiple of these for coverage. Cell is not immune to the limitations of physics, and it has to brute force the situation from the tower end so as we can have small devices in out pockets... and even with all that i get no coverage int he middle of my local supermarket. Do an image search for 'cell panel antenna inside' and see if you can find a picture fo the actual antenna elements, my results mostly got the rear so you might have to scroll a bit.

A lot of the modernisation you refer to is just that given the value we place on connectivity while remaining portable the effort has shifted to needing to bring the signals closer to the user. Looking at that broadly, while some gains have been made what's really happened is that the signal has been bought closer to you, making you think magic has happened.

Yes, antennas are important, but not nearly as important as they were even 10-15 years ago. I couldn't disagree more. The antenna is the single most significant component of any system. I think the best demonstration of this is modern cellular as it shows what has been needed to be done to bring connectivity top the masses and proves there is no way around.