How to Select an Antenna

How to Select an Antenna

We offer tips on how to improve mobile broadband speed with an external antenna for a better internet surfing experience.

Antenna Basics

How to select an antenna: Download speeds in comparisonDownload speeds of LTE/3G/HSPA data connections and connection reliability are heavily dependent on the available signal quality. The signal strength depends on the distance to the base station, your equipment and on the surroundings of your work place. You can compensate for weak elements in this chain by using a suitable additional, external antenna. With an appropriate antenna one can typically improve data throughput by a factor of 2 to 10.

The graph shows the throughput of the cellular connection while downloading a large file from a website. In this case, a Huawei E160 3G USB stick was used together with the ADPT-­026 and the external antenna OMNI-­A0121 mounted outside on the wall of the house. The speed of the download was 3-­6 times higher with external antenna than without, which improves the user experience is significantly.

Two important things to consider when you get an antenna

The first thing is that you get yourself a suitable antenna. The antenna needs to cover the frequency band your provider is using and the antenna needs to have reasonable strength (called “gain”). To be flexible, ideally the antenna has a high gain across all possible frequency bands in question. Most of Conugis’ mobile broadband antennas cover all relevant frequency bands from 860 – 2200 MHz, and therefore will suit any available provider. Often you can find some low price “high gain” antenna, only to discover that it does not work well for your case. Sometimes it is quite tricky to find out antenna gain over different frequency bands, because antenna companies who provide these cheap “high gain” antennas will not give this information. The only way to find out is a datasheet, which actually shows the gain of the antenna across the whole frequency band as a graph. You can find all data sheets forConugis’ antennas in the download area.

The second thing is to get the antenna outside or at least as close to the window as possible. This is extremely important. Walls eat signals. You may know this from your own experience. Stand inside a well‐built house with lots of steel and concrete around you and you will notice that while talking on your mobile phone the connection gets worse while you move deeper into the building and better when standing next to the window (or hanging out of the window….)

Conugis’ Antenna Selection for Poor Mobile Network Reception Areas
Selection of an antenna

Different Antenna Types

In general, antennas are classified as “directional” (sending and receiving in one specific direction) or “omnidirectional” (same sending and receiving qualities all around the antenna).

  • Directional Antennas
    A directional antenna has to be pointed in the direction of the closest base station for best performance. Mount it as high as possible and make sure it has best line of sight. Examples for directional antennas are XPOL-A0002, LPDA-A0092 and LPDA-A0020.
  • Omnidirectional Antennas
    An omnidirectional antenna does not require alignment with the closest base station. It will automatically connect to the closest tower. This allows for easy installation and only requires to be mounted as high as possible. Examples for omnidirectional antennas are XPOL-A0001, OMNI-A0121 and OMNI-A0069.
Directional vs. Omnidirectional Antennas, When to use What

The main issue is how good your signal is outside. Directional antennas in general have higher gain than omnidirectional. The rule of thumb is:

  • If you have a reasonably good signal outside (say 2-3 bars), use an omnidirectional antenna. It is easy to install and you don’t have to worry about where the closest base station is located.
  • If the signal is pretty bad also outside (1-2 bars), use a directional antenna.

Installing an External Antenna

Installing an omnidirectional antenna is easy. The rule is: mount the antenna as high as possible outside on the wall of the house but do not increase the cable length unnecessarily. Cables dampen the signal (depending on cable quality). With an omnidirectional antenna, the cable length should not exceed around 8m (low loss cable like LMR-195), otherwise all you gain with a good antenna would be lost.

Installing a directional antenna requires a bit more work. Again, mount the antenna as high as possible without excessively increasing cable length. With a high gain antenna like the XPOL-­A0002 or the LPDA-­A0092, cable lengths of as much as 15m are possible (providing usage of high quality, low‐loss cable). Then, the antenna needs to be aligned towards the nearest base station. If you use your LTE/3G adapter or mobile phone in order to measure signal strength, you must wait up to 60 seconds until your display shows you the correct measurement. Turn the antenna by increments of 10° degrees to find the direction of strongest signal. It may help to check with your provider where your nearest base station is located. An alternative is to use a mobile spectrum analyzer to help identify the direction of the strongest signal.

A Word on Cables

Antenna cables play an important part on how well the antenna will work (and what it will cost). One of the commonly used cables is RG-58. It is cheap – but not good for frequencies above 1800MHz (like UMTS and HSPA). Cables like HDF‐195 (also known as LMR-195) have the same physical dimensions as RG-58 but only about 0.55dB vs. 1dB loss per meter. If “dB” doesn’t really tell you anything, here is an example: with 10m cable, you will end up with 28% of the signal at the end with HDF195, but only with about 10% with RG58. Make it 20m cable, and you are left with 8% with LMR195 and only 1% with RG58. This is also why it is so important to keep your cable short. The losses are dramatic. So don’t be disappointed if your antenna with an RG­‐58 cable will not deliver what it promises. You get what you pay for.