Anybody try this from CCrane.

[dan2125]

Coaxial Scanner Antenna (BNC)

The top and bottom elements of the Coaxial Scanner Antenna are cut to a tuned length for general scanner listening. Installation is simple, just tack it up on a wall behind a curtain. It increases reception by at least 50% over the standard antenna included with a scanner. 15' feed line. Weight: 9.6 ozs. C. Crane Company Exclusive.

 

[ampulman]

It appears to be an off-center fed dipole which has been written about extensively, here.

I made one from an old pair of rabbit ears, mounted on a tripod. Works very nicely.

I think the 50% claim might be a little bit of hype.

Amp

 

[prcguy]

50% increase would be a 1.5dB improvement, that's not much but is believable.
prcguy