how to share 3g dongle network over wi-fi

You can setup an Ad Hoc network connection by following the directions below:

Windows 7

Open the Start Menu.
Click Control Panel.
Click Network and Internet.
Click Network and Sharing Center.
Under Change your networking settings, click Set up a new connection or network.
Select Set up a wireless ad hoc (computer-to-computer) network.
Click on Next twice.
Enter the Network name such as "LogicNetwork".
Select the Security WAP (or WEP).
Enter the Security key or password.
Check Save this network check box.
Click Turn on Internet connection sharing.


Continue with Part 2 below.Part 2: Connect your mobile device

Tap on the Settings icon in your iPhone main menu.
Click on Wi-Fi.
Your ad hoc network "LogicNetwork" should appear in the list.
Click on you network.
Enter the Password.

i believe android can still not detect ad hoc networks below android 4.0 at least
unless rooted

so try this
http://www.wi-fiplanet.com/tutorials/article.php/3849841/How-to-Create-Wireless-Hosted-Networks-in-Windows-7.htm

Manually create a virtual AP with netsh

If you want to experiment with the wireless Hosted Network feature with text commands, click the Start button, enter “cmd” and hit Enter. Once the Command Prompt window appears, you can enter the following to set the network details:



netsh wlan set hostednetwork mode=allow ssid=YourVirtualNetworkName key=YourNetworkPassword



Of course, replace the SSID and key placeholders with your desired network name and WPA2-PSK encryption key.



Before you enable the Hosted Network, you can configure the real network adapter to share its Internet access using the Internet Connection Sharing (ICS) feature of Windows. This way people connecting to the virtual AP will receive Internet access. You can leave the Command Prompt open so you can start the Hosted Network later.



To enable ICS, navigate through the Control Panel or Network and Sharing Center to bring up the Network Connections window. Then right-click the network adapter that’s connected to the Internet and select Properties. Then select the Sharing tab, check the Allow other network users to connect through this computer’s Internet connection, choose the Hosted Network Connection from the drop-down listbox,
Now return to the Command Prompt and enter the following to enable the Hosted Network:



netsh wlan start hostednetwork



To manually turn the Hosted Network off, enter the following:



netsh wlan stop hostednetwork



To see the Hosted Network details (see Figure 3), including the MAC addresses of connected users, enter the following:



netsh wlan show hostednetwork



To change the WPA2-PSK key, you can enter the following:



netsh wlan refresh hostednetwork YourNewNetworkPassword

’s a virtual AP

Now others nearby should see the Hosted Network appear in their list of available wireless networks. They can connect like normal and enter the encryption key when prompted.



Remember, you’ll have to manually start the Hosted Network again, if desired, after rebooting the computer. Most importantly, remember sharing isn’t blocked; make sure you only invite people you trust.

if your phone is not android you can make an adhoc network

Or you can get one of those 3G to WiFi dongles.

Got my hands on one a few weeks ago and works well. i can use it anywhere (only required a 5V USB port), for my car i got one of those USB chargers and works wonders.

$30 on aliexpress. If you need the link let me know.