I've been using the ZTE Warp Connect on the Sprint network for a while now. (6 months now) It was way better than my DSL connection, but I was barely getting any signal and it would occasionally drop out or latency would jump through the roof.
Luckily the ZTE Warp has a couple of antenna connectors hidden behind plastic flaps I can work with. The connection is a TS-9 female. I did some investigating and found some decent high gain antennas for use with LTE networks, but in the mean time I figured I would try to improve it another way.
The commercial high gain antennas are usually log periodic since the LTE network uses such a wide range of frequencies. The carrier and device you are using will determine what frequencies you will need an antenna designed for.
In my case, the Sprint network uses LTE Bands 25, 26, and 41. This equates to 1900, 850, and 2500 MHz. You can also usually find this information on the hot spot web interface too. On the Warp, you can navigate to the "About" page and find a "Debug" button at the bottom right. When you click on that, it will display all the more advanced connection details, including what band it's connected to. I figured out that my Warp uses band 26 (850 MHz), but can also connect to 25 or 41 if the signal is present and stronger.
Since I know my hot spot is connecting to the 850 MHz band, I began searching for a solid wire that would fit the center of the TS-9 connector. It turns out that solid core network cable works well. I grabbed a couple strands and cut them to 3.3 inches or about 3 5/16". This is the 1/4 wave length measurement for 850 MHz. If your hot spot connects on a different frequency you will need to calculate the wavelength and divide by 4. (1005/Frequency = Full Wave Length in Feet or 234/Frequency = 1/4 Wave Length in Feet.)
|Front of hot spot with wire antennas.
Once cut, remove a small amount of outer insulation from the wire so that it can make contact with the inside of the TS-9 connector. Then, with the hot spot off, stick them into the holes in the middle of the TS-9 connectors.
|Back of Hot Spot with wire antennas and tape to hold in place.
Why 45 degrees? Well if you research how the MIMO (Multi In Multi Out) antenna system works on the LTE network, you will learn that the antennas need to be out of phase from each other in order not to interfere. If I were using the commercial high gain antennas, I would have mounted them at opposing 45 degree angles too or mount one vertical and one horizontal.
How well did it work? Pretty well. I'm still on the outer edge of service so the power received from the tower is still pretty low, but all the other figures were bumped up into the medium or good range and I have a steady 1 bar of service as opposed to the device simply saying it's connected with 0 bars. So far I haven't had any drops of service and best of all I'm getting close to 6 Mbps download and 4 Mbps upload. Before it was only about 2 down and 200 kbps up. I'm also getting consistent latency ratings under 80ms instead of 400ms or more.
I have the high gain antennas on order and I'll make a post about those too, but if you want an extremely cheap way to improve your hot spot signal, this should do the trick.