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Cascading all the above tricks will probably give diminishing returns as the last tricks are done. Doing just one should give the greatest increase in gain. Adding another trick will give yet more gain, but not as much beyond what the first trick did, on average. There's only so much signal out there to be heard, anyway.
Improving signal to noise of an AM radio with ferrite rod antennas.
AM radio station signals are half magnetic and half electric fields. Noise tends to be mostly electric fields. Placing some electrostatic shielding around the antenna can improve signal to noise of radio station reception. A cardboard tube like the sort from a roll of toilet paper can be used as the basis of such a shielded antenna. Wrap aluminum or copper foil around the tube, but leave a gap as shown above. Otherwise you will have a shorted turn and that will give both magnetic and electric field shielding. And thus no reception! Connect the foil to an RF ground. Place the cardboard tube around the ferrite rod, positioning it over the area where the antenna coil is. Maintain at least a quarter inch (7mm) clearance to avoid excessive stray capacitance (which will impact the upper end of the band the most). Spacers like large rubber grommets could be used for this.
Expect to loose 6dB of signal, and hopefully more than 6dB of noise. You'll need to tweak the antenna trimmer to compensate for whatever stray capacitance was added by the shield. With the other tricks on this page, that signal loss shouldn't be a problem.
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