Sierra Wireless LTE Modem Guide: Adapters and Antennas


So you took my advice about which modem to buy and settled on either the EM7455 or the EM7565. Now you need a way to connect that modem to a USB port for use on your desktop or router.



This post is part of my Sierra Wireless LTE Modem Guide Series. If you prefer to skip the blog nature of these guides and just grab the bare features and commands, my GitHub repository will serve as the authoritative source for this entire series. Any changes or updates will occur there first.


M.2 B-Key to USB 2.0 Adapter With SIM Slot
My preferred enclosure is the M.2 B-Key to USB 2.0 Adapter With SIM Slot from eBay that costs a mere $22 shipped from China. If you are in a bit of a hurry, order it from LTEFix.com. Jim operates on pretty low overhead, so his prices are very reasonable if you need it next week instead of in three weeks. This enclosure and any EM series modem are all you need to get started. The package includes everything else. On the downside, it is only USB 2.0 and the included USB cable will not work very well if you are far from the tower(too much voltage drop in a high gauge wire). With the EM7455 that is a non-issue as there is basically no scenario in which you could realistically saturate the USB 2.0 bus.

BPlus USB 3.0 M.2(NGFF) Card Adapter


If you are on Sprint with the EM7565 in a 3CA B41 area, USB 3.0 should definitely be a consideration. While the enclosure is over $100 shipped from Taiwan, it is currently the only realistic method of achieving > 300Mbps with the EM7565.


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So while that covers Adapters, what about antennas?
If you already get great signal from your preferred LTE carrier on your cell phone, chances are high that you will have as good or even better signal with the included 3dBi Omni antennas included with the $22 Enclosure above. You can cheaply increase this by ordering the pair of RP-SMA 9dBi Omni antennas.

If you are on the edge of coverage, external antennas will prove an incredible asset. As in all thing when dealing with radios best friend is a clear line of sight. Height will typically reduce obstructions (including clearing the Fresnel zone by being high enough off the ground). Your ideal setup will be a dual Yagi/Log Periodic setup with the modem itself very close by. There is no point in gaining 10dBi of signal just to have it eaten in 20ft of low quality coax.

bnhf Outdoor ROOter Setup

If you are using the $22 Enclosure, you’ll need new MHF4 (that’s the modem connector) to SMA pigtails. Or you can spend $2 and get a pair of RP-SMA to SMA adatpers.

If you are at an extreme edge of coverage, and are willing to spend the extra money to go the extra mile, Jared (dajmanjt) on the LTEHacks forum has an excellent writeup on some solutions he has used.

I’ve seen setups like this turn marginal signal Verizon setups from 2-3Mbps max, to consistent 20Mbps. That was in the old days on a MC7750 connecting to a tower about seven miles away. If you don’t mind having the modem in such an enclosure, but don’t want your router outside like this, consider getting a cheap router instead. Every other option is complex and requires quite a bit of technical knowhow (USB2 extender + powered USB hub inside the enclosure) and make you reliant on unknowns.

Comments

  1. M.2 B-Key to USB 2.0 Adapter With SIM Slot cannot be used with EM7565. It is very unstable. EM7455 is working fine with this adapter. I have tried better USB cables and powered USB 2.0 hub with EM7565.

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