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At the time of writing this FAQ, Vodaphone, 3, Optus and Dodo have been using the Huawei E160 wireless USB modem (USB Stick) on the 3G network. This article is about these modems (not the Telstra Next G ones).
Depending on where you are, signal strength can be an issue and you may need to find a way to boost your signal.
The easy way to increase signal strength is to put the USB stick on a USB cable and hang it up high. Unfortunately these little suckers need a fair bit of power - they will use any last drop of power that your USB buss can deliver. If you use a USB cable over 2m, or a bad quality cable, the voltage drop is enough to give you unreliable results. I've also tried using powered USB extension cables (5m), however the reliability is still suspect. There is only 500Ma available per USB2.0 port, and a powered USB extension cable only takes more power away from the USB Modem.
However these modems have a small CRC9 antenna socket on them. You can attach various extrenal antennas with them. 3G Antennas are best, but WIFI will work. The common connection on the small antennas is the RP-SMA - so you will need a CRC9 to RP-SMA adaptor.
(Note: This is not an MC connector. The MC plug is smaller again)
RP-SMA connections are confusing. There are the external thread to match, as well as the internal pin.
These modems also have several modes. The LED changes colour depending which mode it is working on:
- Cyan: HSDPA - 14 Mbit/s (Fastest)
- Blue: WCDMA - 2 Mbit/s (Medium)
- Green: GPRS - 115 kbit/s (Slow)
If the mode is frequently changing, your connection may become unstable. You can set a preferred mode via the software that comes with the modem.
Radio Frequencies
It is good to know about the transmission frequencies when selecting your antenna. In Australia the 3G frequencies is 2100MHz and GSM is 1800MHz and 900MHz. 3G is the faster band available in city centres, GSM 900 is more availabe in regional area. (US Cellphone frequencies are different).
WIFI antennas, like those attached to your wireless ADSL router, are 2400MHz. These still seem to work ok for 3G modems.
| WIFI |
2.4GHz |
| 3G |
2.1GHz (in Australia)
|
| GSM1800 |
1800MHz (in Australia) |
| GSM900 |
900Mhz (0.9GHz) (In Australia)
|
| TV UHF |
500 - 800MHz |
| TV VHF |
45 - 230MHz |
| FM Radio |
88 - 108Mhz |
| AM Radio |
0.5 - 1.6MHz |
The Higher the Frequency - the greater the attenuation.
For a Chart of Australian frequencies -  Australian Frequency Chart
Cable
Due to the high frequecies of 3G and WIFI, ordinary TV cable isn't really suitable. If you use TV cable, you could find that you'll loose a lot of signal strength per meter. The Low Loss RF cables are the way to go, their shielding is tighter.
Recommendation:
- LMR-400 (~10mm) for runs over 6m (Rigid cable).
- LMR-195 (~5mm) for runs 3m - 6m (Flexible).
- Thin cable - for runs less than 3m (Flexible).
| Attenuation (dB per 100 feet) |
| MHz: |
30 |
50 |
100 |
146 |
150 |
440 |
450 |
1000 |
2400 |
| #2632 |
RG-174 |
5.5 |
6.6 |
8.8 |
13.0 |
|
25.0 |
|
30.0 |
75.0 |
| #0985 |
LMR-100A® |
3.9 |
5.1 |
|
8.8 |
8.9 |
15.6 |
15.8 |
|
|
| #2619 |
RG-58A/U |
2.5 |
4.1 |
5.3 |
6.1 |
6.1 |
10.4 |
10.6 |
24.0 |
38.9 |
| #3603 |
LMR-200® |
1.8 |
2.3 |
|
3.9 |
4.0 |
6.9 |
7.0 |
|
16.5 |
| #2910 |
RG-59 |
|
2.4 |
3.5 |
|
|
7.6 |
|
12.0 |
|
| #2247 |
RG-8X |
2.0 |
2.1 |
3.0 |
4.5 |
4.7 |
8.1 |
8.6 |
|
21.6 |
| #3604 |
LMR-240® |
1.3 |
1.7 |
|
3.0 |
3.0 |
5.2 |
5.3 |
|
12.7 |
| #3605 |
LMR-240 Ultra® |
1.3 |
1.7 |
|
3.0 |
3.0 |
5.2 |
5.3 |
|
12.7 |
| #2248 |
RG-8/U FOAM |
|
1.2 |
1.8 |
|
|
|
|
7.1 |
|
| #2929 |
RG-213 |
|
1.5 |
2.1 |
2.8 |
2.8 |
5.1 |
5.1 |
8.2 |
|
| #0390 |
RG-214 |
1.2 |
1.6 |
1.9 |
2.8 |
2.8 |
5.1 |
5.1 |
8.0 |
13.7 |
| #3606 |
LMR-400® |
0.7 |
0.9 |
|
1.5 |
1.5 |
2.7 |
2.7 |
|
6.6 |
| #3607 |
LMR-400 Ultra® |
0.7 |
0.9 |
|
1.5 |
1.5 |
2.7 |
2.7 |
|
6.6 |
| #0812 |
9086 |
|
|
1.4 |
|
|
2.8 |
2.8 |
|
|
| #0075 |
9913 |
0.8 |
|
|
1.5 |
|
2.8 |
|
|
7.5 |
Connectors:
The N connectors are usually used for 5mm coax and above. They are good for up to 12.5GHz.Larger antennas usually have a N Female connector.
SMA Connectors are good for 5mm coax and below. They are rated to 18GHz.
F connectors (used commonly for TV cable) are only good for 1GHz, so although they are great for TV - they aren't the best for WIFI and 3G.
More Info:
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Female RP-SMA Connector on a Router
Comments
@Mani: The 3G and VHF operate at different frequencies - so the aerials are different lengths. It won't be operating very efficiently.
Could you tell me could I use my boats vhf antenna to connect to the 3g router boost weak 3g signals,
Thanks for youe help
I'm not sure if I understand the question. The CRC9 socket is used for some of the USB Modems. You'll need to find an Antenna with a CRC9 plug (or use an adaptor) to plug it into the USB modem. The cable by itself will be shielded and won't (normally) pick up a good signal - so you'll need an Antenna at the end of it.