ngu,

Since you live in Hong-Kong, I suggest you to get a Degen DE-31/Kaito KA-31
active antenna. It is another portable active loop, much cheaper than the Sony.
It is said to have lower performance than the Sony but to be a good bargain due
do its low price ( 20 US$).

You can see a review here (with Sony comp.) :
http://www.radiointel.com/review-degende31.htm

I have purchased one, but I don't have yet... A few days more to wait until it
ships to me !!

So far I've been using a home made wire dipole. Assuming your radio has a
external antenna jack connector or the like, you can give it a try. I've posted
the recipe a few days ago but I can repost here.

You need :
- coax feed line maid out from a piece of TV coax
- two thin wires, one connected to the center line of the coax,
the other connected to the shield.
- a suitable connector to your radio (1/8" mono jack for my Sangean)
connect center wire to connector tip, coax shield to the connector ring

You extend the two wires in opposite directions and it makes a portable random
dipole. Mine is about 5m fully extended, just because I had this length of wire.
No computation or studies to match specific frequency or having right impedance.
In buildings made of iron structure, I put it on a window with adhesive tape, or
let it hanging outside, trying to keep the two wires apparts.

This greatly improved my reception on all bands. I must say I tried mainly in
the lower bands in frequency (F = 15000 kHz) since I'm mostly listening at
night. MUCH BETTER than the piece of random wire I tried in the same conditions.

Hope this helps,

Charly