[Hawthorn]

>> The reception is still going to be limited by the capture area <<

What about ferrite-core loopsticks? They occupy a tiny space but pick up a lot of signal.

[backwoods-engineer]

Ferrite-core loopstick are good for only low-frequency signals, like shortwave or the AM broadcast band. In the cell phone bands, their losses would be so enormous as to be unusable.

But the loopstick is only one of a class of electrically-small antennas (small compared to the wavelength in free space). Electrically-small antenna theory has been fairly stable since the 1960's, though there has been some minor refinements.