Cellular Signal Strength

Means the cause of slow internet at home is a signal. Hmmm ... googling results on the internet there are several ways to improve the signal that is an additional antenna, external antenna and repeater. In this paper the author only discusses the antenna that can be made yourself with the cost and effort is affordable.

Many additional antennas are sold on the internet with prices varied from Rp 35,000 to above Rp. 100,000, but the review of the forums that the author of the research, the increase is less significant. So the author discouraged to buy such an antenna.
Your HP Antenna Type

On some HP and modems that use internal antennas (antennas do not poke out) there is a socket plug for an external antenna. This socket is covered by a rubber cover that can be opened by prying. Try looking at the edges or back of your HP / modem. If you already see open and see yellow round socket.

Some HP (especially flip-shaped ones) have antennas protruding out and some can be opened by rotating. Maybe it meant to be replaced with a larger one.
Wire of Copper Wire

This is the simplest and reasonably priced. Take a 30-50 cm copper wire and wrap it 2-5 times on the HP then peel away the cable about 10 cm and go up your phone (like the antenna). Benefits that can improve signal reception up to 2 bars even 3 bars. Be careful with the end of the cable that can scratch the casing / display of your HP.

This can be varied by soldering the end of the cable with an antenna socket, then connecting with your antenna socket as mentioned above. For HP without sockets this can not be done.

The optimal antenna length for GSM 900 is 33.3 cm while for GSM 1800 is 16.7 cm. The formula is antenna length = C / Frequency; With C is the speed of light = 300,000,000 m / s.

If appropriate then the gain of the signal obtained can reach 2 bar (scale 5) either GSM or 3G signal.
Paper Clip Antenna and Hanger

This is a free way to increase your HP revenue but with little export. The tools used are clips, pointed pliers and masking tape. First take a paper clip, then straighten the ends with a pair of pliers, then bend 0.5 cm of the clip tip 90 degrees to the clip (as a plug for the HP socket). Attach the end of the clip to your HP antenna socket and tape it to the HP body.
Antenna Tesla Coil

By leveraging the principle of tesla coil, you can maximize your HP signal reception. This trick can only be used HP that has a prominent / outer antenna. The materials used are thin wires (such as those for cable ties) and insulation. Wrap the wire on your HP antenna, 5-7 loops sufficiently then insulate the coil. Voila. Check your HP receipt.

The author does not know the amount of signal strengthening for this type, from googling on the internet, this way can increase signal up to 2 Bar (5 scale).
Old Radio Antenna

Your old unused radio antenna can be used to amplify your mobile signals. You do this by connecting the antenna with your HP antenna socket. Better yet, if you make a socket to attach the ANtena to your HP. This can increase the signal GSM 1 bar and 3G signal as much as 2 Bar (Scale 5).
Other ways

Some other ways that require enough effort include: (you can do googling for more info lebh)

Canned Antenna
Antenna Cover Pot
Antenna Wok
Pralon antenna
Combined Antenna-Pralon Antenna