You can buy a USB Wi-Fi dongle that has long USB cord, a dongle base and put the actual dongle by the window. May help a little bit, but do not expect to much.
You can buy Wi-Fi signal extenders that can transmit and receive Wi-Fi signals over a mile and up to 2 miles away (line of site). There are a few manufactures out there and some posts on this site. Expect to pay anywhere from $85 to $400. Mine was $85.
If you decide to go with extended Wi-Fi signal extenders, you will need to know or learn how to set them up, as some of the documentation leaves a little to be desired and some company support is not always available. A full pot of coffee or 6 pack of beer may also be required.
There are two types of these external Wi-Fi signal extenders, those that have the antenna included in the Exterior unit or those that require an external antenna and a coax cable from the antenna to the unit (mounted in the rear storage compartment). I chose the external antenna model, as it is omni-directional where as the units that include the antenna as part of the unit have about a 75 degree angle for transmit and receive. Both need to be mounted outside the RV and a cat5 cable runs between the Wi-Fi signal extender and a regular Wi-Fi modem used by all your Wi-Fi devices in or out of the RV.
Is it worth it? In my case it has been well worth it. I tried to use Verizon MyFi, but we use toooooooo much data and it cost us an arm and a leg for one month. No matter where we park in the CG's we ALWAYS have a GREAT signal. But to carry that one more step, if you set the unit up for MAX signal/Distance you can pick up Wi-Fi signals from other public Wi-Fi providers. While in Colorado last summer, we stayed at a state CG with no Wi-Fi.. Looking up on a ridge about 1.5 miles away was a Home Depot that has Public Wi-Fi. I put my antenna up to its max height and was able to connect to their Wi-Fi. As far as signal strength, I was able to stream video from my Slingbox at home here in FL, without any breakup. I had to watch the Ray's ball games and our recorded shows. At another CG without Wi-Fi, we were able to connect to McDonald's Wi-Fi (about 1/2 mile away). I have no problem with using their signals as we donate a large sum of money each year to support their businesses... $140 yesterday to HomeDepot :-(
So, yes they do their job well, but they do take a little time and understanding to get them up and running. It would help if you could enlist the aid of a person that understands the network. I use an EnGenius EOC5611P. I get to the CG and with my tablet I set the unit up to connect to the CG AP, and all our Wi-Fi gizmos link up to the TT's Wi-Fi router and have access to the Internet.
Here is the link to my Wi-Fi album, hope it helps:
Again it is not for everyone!!!! And there is NOT always a PUBLIC Wi-Fi in the transmit/receive area.
Just my thoughts,
2013 Jayco Eagle 284BHS
250Watt Grape Solar Panel, MorningStar MPPT 60 Charge Controller
1500 Watt Ramsond PSI, 2 Trojan T145 Batteries (260Ah)
2 - AirSight Wireless IP Cameras (used as rear view cameras)
EnGenius WI-FI extender, D-Link wireless (n) modem
MagicJack Internet Phone
2012 Ford F150XLT, EcoBoost w/3.73
157" Wheel base, HD Towing Package
Our Solar Album http://www.jaycoowners.com/album.php?albumid=329