Cellular antenna selection and connection

This article looks at basic cellular antenna configurations for Opengear devices which include an internal 3G or 4G cellular modem (i.e. models with -Gx or -Lx suffix respectively).

The quality of the cellular reception is determined largely by your antenna and its location. Refer to this article for more information on measuring signal strength.

All Opengear cellular models have standard female SMA connectors for attaching antennas.  In the general case, your Opengear device will be supplied with sufficient and appropriate antenna(s) for you to establish a cellular connection.

4G antennas

Opengear -Lx (4G) models are supplied with two antennas of either regular (part #569017) or blade style (part #569028).

569017 / 569028: 4G, 3G 7-band antenna, swivel SMA male, 0-3dBi gain, 700/850/900/1800/1900/2100/2600 MHz

For full speed operation, -Lx models require that the antennas are connected to both MAIN and AUX (for radio diversity) SMA connectors.  The two antennas are interchangeable and the cellular modem automatically utilizes both antennas as required. For more information on dual antennas, refer to this article.

3G antennas

Opengear -Gx (3G) models were supplied with a single main 3G antenna (part #569006).

569006: 3G 5-band antenna, swivel SMA male, 0-3dBi gain, 800/900/1800/1900/2100 MHz

-Gx models require that the antenna is connected to the MAIN SMA connector. If you have a low quality connection (e.g. low signal strength), you may purchase and connect an optional second antenna to AUX for connection diversity.

You may use part numbers 569017 or 569028 with -Gx models, with the caveat that they do not support the 800Mhz frequency.

Antenna extender

In some circumstances it may be preferable to place the antenna away from the Opengear device because of poor access, limited space or poor reception – optimum placement of the antenna can dramatically improve cellular connection quality.

To facilitate this Opengear supply an ultra low loss 10ft/3m extension cable and with screw on magnetic base (part #449041) as an optional accessory.

449041: Extension cable, dual SMA male, RG174U ULL coaxial cable, length 10ft/3m, magnetic base

The standard antenna connects to the magnetic base, which can be mounted e.g. on the top of a rack, to mitigate any Faraday cage effect.

For small form factor units, also consider repositioning the Opengear device itself to maximize cellular reception, and extending the cat 5 cabling to reach.

Third party antennas and cabling

In some cases it may be preferable to attach an external third party antenna (e.g. with higher gain, and/or a YAGI directional antenna) instead of the ones supplied.

Note that many antennas are not universal so please ensure that the bands they support are appropriate for your carrier and location.  Also it is best to try them in a few locations for a short while before standardizing on particular models. If you are using an external antenna on the roof or exterior wall of a building it needs to be safe to use in wet environments and have lightning protection.

Finally, you may need to run an extension cable further than the 10ft/3m the Opengear antenna extender supports.  As Opengear devices are equipped with standard SMA female connectors, they are compatible with standard coaxial cabling, e.g. low-loss LMR400.