How to Choose an External 4G or 5G Mobile Broadband Antenna

Likewise the operators won’t always deploy all of their available bands everywhere they go; sometimes it makes more sense to tailor choices to a specific area. The good news is that you can usually identify what bands are being used by downloading various apps (e.g. Network Cell Info Lite on Android devices) or finding the mobile network details page on your Smartphone or router.

Consumers who happen to be using one of Huawei’s mobile routers can also try checking out the LTEInspecteur software for Microsoft Windows, which gives you lots of access to advanced signal stats and even allows you to tweak which band you use (assuming the operator gives you a choice and it’s supported by your router/antenna).

Often such apps and pages won’t tell you the spectrum frequency and will just give a band number for your own operator (take a look here to see what spectrum the operators currently own). Operators will often own several bands, although they usually have one primary band for national connectivity (e.g. Vodafone and O2 use B20, while EE and Three UK prefer B3 on 4G).

Common 4G Mobile Bands in the UK
800MHz (Band 20)
900MHz (Band 8)
1800MHz (Band 3)
2100MHz (Band 1)
2300MHz (Band 40)
2600MHz (Band 7)

The next challenge stems from identifying your nearest mast(s) / cell site(s), or at least the most appropriate one for your location. This may be impacted by the local topography, surroundings and operator choice, so it’s not always the most logical or nearest one. The app mentioned above can help but you may also find useful data on these two websites – Mastdata.com and Cellmapper.net. The Opensignal app is also worth trying.

Take note that some network sharing agreements do exist between operators, which can complicate the picture. For example, Vodafone and O2 have a network sharing agreement under Cornerstone (formerly CTIL), while EE and Three UK have one via Mobile Broadband Network Limited (MBNL). As such one mast or cell site may potentially be serving more than a single operator.

Understanding signal strength

Next up it helps to understand “signal strength,” which tends to be reflected by several measurements (e.g. RSSI, RSRP, RSRQ, RSCP, SINR and EC/IO). You will need at least a basic understanding of these, or at least two or three of these, in order to better position your antenna.

Measures of Signal Strength
Received Signal Strength Indicator (RSSI)

Reference Signals Received Power (RSRP)

Reference Signal Received Quality (RSRQ)

Received Signal Code Power (RSCP)

Signal-to-Interference-plus-Noise Ratio (SINR)

Understanding each one of the above is useful but it can get confusing and so we’ll focus on RSSI and RSRP/RSRQ because you’re most likely to come across those on 4G Mobile networks (as well as others like WiFi etc.). Generally all of these are indicated by a negative dBm (decibel milliWatts) value, which conversely means that negative values are actually good.. up to a point. The values here are negative because they actually represent small but positive numbers, albeit on a logarithmic scale (otherwise we’d be have to express, for example, a -100dBm signal in an uglier way like this: 0.0000000001 mW).

For example, an Excellent 4G RSSI signal would be -65 dBm, while a Poor signal would start at around -85 dBm. In simple terms, the closer to 0 dBm the better, although mobile networks are designed to have a wide coverage and so past a certain point there can be an issue of diminishing returns – in terms of data speed – on the way to a perfect signal. The measure for RSRP is similar to RSSI, except an Excellent 4G signal is had at -80 dBm.

Meanwhile RSRQ operates on a very different scale, which means that anything from around -10 dB (not dBm) is Excellent and – 20 dB would be considered Poor. However mobile modems are actually quite good at maintaining a reasonably fast data connection with even a poor signal, although slower speeds and worse stability will become more of a problem the weaker it gets (e.g. rural areas far from a mast).

For example, here’s a real-world reading we got from an indoor Three UK link on a Smartphone that was only about a quarter of a mile from an admittedly fairly congested urban cell site (using the ‘Network Cell Info Lite‘ app).

On the phone itself the result above (-95 dBm) gave us about 4 out of 5 bars of 4G signal, even though it’s not an ideal dBm score (those bars on your phone are NOT a good gauge of signal quality), yet mobile broadband speeds were 5-14Mbps.

However, when outside on the roof of our building this jumped to around 25Mbps with an RSRP score closer to -85 dBm, where it also became much more stable. Sadly the speeds didn’t improve much after that, even when walking closer to the cell site, which is probably down to limitations of the bands being used or the fact that the local data capacity may have been fairly congested with lots of users.

Common Questions and Tips

1. Why is my antenna better on a window than outside?

Sometimes you can do everything right and still end up with a bizarre situation, such as where your Smartphone gets a better signal / data speed indoors than a correctly positioned external antenna. Alternatively the antenna might get a better reception when sitting indoors on a window upstairs than fixed outside near the top of your house.

Unusual situations like this can be caused by all sorts of issues, which is why it pays to understand the signal readings and bands being used (as above) in any given location around your property. Mobile signals can suffer from all sorts of quirks, like reflections from other objects in the environment or changes in weather, and sometimes the router you’re using will switch bands automatically (depends on location, operator etc.) only to put you on one with slower speeds.

This is why we say that sometimes the most logical solution isn’t always the correct one. As such it often pays to spend some time testing different locations for both your router and antenna to see how the measurements change. In the course of doing this you might end up finding that an antenna was never required in the first place.

2. Borrow a friend’s SIM or handset.

Sometimes the best way to understand what kind of service may be optimal for your area is simply to borrow a friends phone, assuming they’re on a different network to yours, and run a few tests in different areas (take some signal measurements and do a few broadband speedtests). If possible you should try to do this for all of the major mobile networks and use a modern Smartphone.

We’d also recommend only using Pay Monthly SIMs as sometimes PAYG SIMs may have restrictions on data connectivity, which could give you a misleading result.

3. Ensure the router supports Carrier Aggregation (LTE-Advanced).

The term CA simply means the ability to combined several different radio spectrum bands at once in order to boost performance. The latest 5G networks and many urban 4G deployments should all support CA, although sadly these don’t always reach rural areas, but it’s still wise to only purchase kit that has support, just in case.

Devices that support the 3GPP Release 10 standard also support LTE-Advanced, although CA became much more refined from Release 12 onwards. Meanwhile the first 5G features tend to start at Release 14 onwards. You might also come across a reference to LTE Categories (e.g. Category 6), which helps to identify the peak theoretical downlink and uplink speeds of a 4G modem.

For example, 4G based Category 6 hardware can usually handle downloads of 300Mbps and uploads of 50-100Mbps, while Category 19 kit may be able to deliver 1Gbps+ speeds (i.e. on an ideal network with lots of CA and capacity to spare – in practice you’ll almost never achieve the peak). Modern mobile routers should all support a good selection of bands and speeds.

4. Beware different antenna connectors / sockets.

Not all mobile routers and antennas come equipped with the same external port type (some routers don’t even allow external antennas) and so it’s wise to ensure that you check what both bits of kit use before buying. The most common connector type is thankfully SMA, although you’ll probably also come across TS-9, CRC9, RP-SMA, TNC, BNC, N-Type, MMCX, FME and U.FL.

However don’t worry too much if you make a mistake and mix up different connectors because it’s often possible to buy adapter cables, which can convert between two different connector types. The picture alongside shows an SMA (Female) connector in gold and a TS-9 in silver, which are quite common.

5. Keep an eye on the CELL ID.

Some devices and apps won’t allow you to see what band is being used but they often do still report the CELL_ID number for the signal source (mast / tower etc.). If the CELL_ID number changes then the signal is coming from a different source and your device might at the same time end up using a different band, which can be another useful indicator when diagnosing performance issues.

6. Good Signal = Bad Speed, Bad Signal = Good Speed?

We’ve touched on this a little already in the article above but the point does need to be rammed home that a good signal doesn’t always equal good speed. Sometimes you can have an excellent signal but the band you’re connecting to may be congested, with lots of users, or it might simply not be able to carry much data (not enough spectrum frequency). Conversely this also means that you can sometimes get a better speed but with a worse signal quality. Like we said earlier, mobile signals can be quirky so.. test, test and test some more.

7. Rule out WiFi.

One important, if obvious, little point is not to confuse the potentially poor performance of the WiFi signal from your mobile broadband router with that of your mobile signal. Sometimes people get poor speeds as a result of WiFi and don’t realise that the mobile signal itself is fine. The best way to test your setup is thus to plug into a wired LAN port first and only use WiFi for connecting devices once everything else is working as intended, which will help to avoid any confusion about the cause of a performance issue.

8. What about indoor antennas?

In our own direct experience we’ve tended not to achieve much of a signal improvement from using indoor antennas. Some of the units on sale make big claims for fairly cheap hardware, although they’re no substitute for a well made and correctly installed outdoor antenna. However if you still want to give one a go then try the Poynting Omni indoor/outdoor SiSo antenna.

Hopefully this guide has helped you to understand some of the basics when it comes to choosing and setting up an antenna to help improve your 3G, 4G or 5G mobile signal. Since 2018 EE has also been offering an external antenna installation service (here) alongside one of their own mobile broadband products (4GEE Home Broadband), although you have to call them to get any details on this (number given is 0800 079 0131).

One other useful tip is to consider buying a mobile router from Huawei. The reason for this is that they tend to make fairly good kit and most of the mobile infrastructure being used today also comes from the same manufacturer, although this may change with the 5G rollout. You’ll also be able to use the aforementioned LTEInspecteur software, which is another bonus.

In terms of antenna choice, some of the best kit tends to be made by Poynting. At the entry-level there’s the Poynting 4G-XPOL-A0001 cross polarised omni or the 4G-XPOL-A0002 cross polarised directional, although if you want higher gain then be prepared to pay a fair bit of money for a good one like this – Poynting 6.2dB MIMO (sometimes you’ll end up fighting the laws of physics and a bigger investment might not be worth it).

Finally, the new generation of 5G mobile services are still being launched and Ofcom has yet to release all of their planned bands for this. As such recommending any antennas for 5G services tends to be a bit tricky right now, although some of the more expensive units do support the related bands (e.g. XPOL-2-V3-5G).