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Antenna Considerations for 4G/LTE

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Objective
To try and clarify factors that you need to consider when planning on using an external antenna for your 4G/LTE broadband connection.
With 4G (LTE) services starting to come onto the UK market a lot of users are finding that they are achieving download speeds that are lower than they were expecting to get. Often this can be due to poor reception however there are other factors that need to be understood which can affect the broadband speed.

Hopefully this short article will help explain the implications and considerations the user needs to examine before they can decide the best course of action.

MiMo technology

Okay… first things first. What many users do not understand is that LTE is a multi-stream radio, MiMo (multiple in/multiple out) service. btw I’m going to stop using the term 4G; LTE is NOT 4G. The 4G term has been jumped on by various bodies e.g. telco/ISP/Government who don’t fully understanding the technology but 4G sounds better to the end users. I’m not going to go into it here but LTE is not 4G; Wiki has several good articles for any readers that want to read about why LTE isn’t 4G. Anyway… so LTE is multi-stream MiMo technology. This is like 11n WiFi (which is also MiMo). One of the ways that LTE gets it’s performance improvements is to use multiple radio data streams to and from the end client. Just like 11n WiFi, the more streams of data the client can take then the faster the effective broadband.

Like 11n WiFi, the terminology which denotes the number of streams is expressed as TxR where T is the number of transmit radio streams and R is the number of receive streams the connection can support. So, if a client supports 2×2 streams then it can generally support twice the upload and download speed of a 1×1 device. In the world of LTE you can have anything from 1×1 right up to 8×8 stream capability with all the possible mixes in between.

In simple terms a client device needs to have an antenna for each radio stream. For a 1×1 service then the client just needs a single antenna. For a 2×2 service the client needs two antenna, and so on. So the number of streams a connection can support depends upon the capabilities of the service providers masts and also the radio capabilities of the client device.

The majority of LTE dongles and routers currently being supplied by the providers are 1×1 devices. I suspect there are several reasons for this:
1×1 devices are cheaper (if the teloco’s giving something away then they want it to be as cheap as possible).
If the clients only have 1×1 devices then the maximum speed they can download is reduced which means the local telcos mast can service more users and the data backbone costs per user for the telco are minimized (or maybe that’s me just being cynical).

If you look around you will see various types of LTE (4G) antenna being advertised at range of different prices. One of the differences between these antenna is the number of antenna connections they have. Typically you will see antenna with single connections (so this is for 1×1 client devices) and antenna with dual connections (so this is for 2×2 client devices and also for 2×1 or 1×2 devices). As a general rule dual antenna cost a lot more than single antenna.

If your client device (dongle, router, whatever) only has a single antenna connector then there’s just no point in getting an LTE antenna with dual connections; you’re just wasting your money. On the other hand if you do have a dual connection device then you must use either two single connection antenna or one dual connection antenna. If you don’t then you will limit your potential data throughput (of course I’m assuming that the mast/service from your telco/ISP actually supports multi-stream).

So, if we look at the Solwise range of LTE antenna we have the Poynting A0121, as a 1×1 omni antenna:
https://www.solwise.co.uk/3g-antenna-omni-a0121.htm
and we also have the Poynting XPOL-A0001 which is an omni 2×2 antenna:
https://www.solwise.co.uk/4g-antenna-omni-xpol-a0001.html

Frequency Bands

In some countries there is just a single frequency band used for their 4G service. The advantage of a single band is it makes the client devices cheaper and it also simplifies the antenna. It’s much easier to make an antenna to cover a single frequency range, e.g. you might just have to cover the 850MHz band, than it is to have to cover three different bands as disparate frequencies. The UK is probably the worst with LTE services spread across  three widely different bands. i.e. 791-862MHz, 1710-1880MHz, and 2570-2620MHz. I suspect there are several reasons for this:
The UK didn’t have a wide enough frequency band free to allocate as a single range

The more frequency space available then the more money Ofcom can make in flogging the licenses to the telcos (again, maybe that’s be being a cynical git!).

In the Ofcom LTE auctions in early 2013 the following allocations were awarded:

4g-lte-allocations-table-ofcom-2013
In addition to the above, Everything Everywhere, also have use in the 1800MHz (this was decided before the auction). As you can see the allocations are all over the place.

Actually it’s even more complicated because some providers have more than one licensed band e.g. Vodafone has frequency allocation in both the 800MHz band and also the 2.6GHz band, and the band used varies across the country and signal mast! Generally, because the lower frequency bands give longer transmission range than the higher frequencies, then the lower bands are used in more rural areas where a mast needs to cover a geographically larger area. Conversely the higher band would be used in more built up areas like towns or cities. However this isn’t a definite. I suppose there’s no reason why a provider might not decide to use a 2.6GHz service in a rural area – it’s not fixed in stone.

The implications for the end user are you need to ensure your antenna suits the providers service. So, if you get an antenna suitable for EE on their 800MHz band and then change to a service that uses 2.6GHz then the antenna may or may not be suitable; it just depends if you were sensible in the first place and picked an antenna that can cover 800MHz and also 2.6GHz. All of the LTE antenna from Solwise clearly state the frequency bands they support. In fact we’ve made a conscious decision to only stock LTE antenna that are suitable to all three UK LTE bands so you don’t have to worry about choosing which band antenna for which supplier.

Stream Bandwidth

From the Ofcom table above you can see that spectrum allocated to the providers was split into individual sub bands. e.g. EE were allocated spectrum of 2x5MHz in the 800MHz band. So EE could use this as a 2×2 service with 5MHz per stream or as two 1×1 services. According to the specs for e-UTRA (this is the air interface for LTE) each 5MHz band can cope with up to 200 users. As such, in areas of high user density, you might find that the provider prefers to deliver it as two 1×1 services in order to maximize the number of users.

So let’s look at the download rates specced for LTE: A mythical link using 4×4 with 20MHz wide streams is supposed to give 300Mbps and a single 20MHz wide stream (or, presumably, two 10meg streams running as a 2×2 service) works out at 75Mbps. Scale that down to a 5MHz stream as you arrive at about 18Mbps. Note these are the transport data rates; the actual download throughput performance of the user equipment will depend upon the signal conditions, capabilities of the providers connection etc. Remember as well these data rates are shared between all the users. Get 100 users connected to the mast and that 18Mbps ain’t going to go very far! Of course, since 99.99% of users are only going to be using their connection for simple things like checking their online Facebook postings or maybe watching incredibly poor quality (low res) videos on their 2inch phone screen, then most people won’t even know!

Okay… so the conclusion is that 4G (LTE) might be considered as just a load of ISP hype? Me being cynical again!

Omni or Directional?

It doesn’t matter if its WiFi or 3G or LTE, most users think just get the highest gain antenna I can find and, invariably, this means a directional antenna. However in the majority of cases a directional antenna is a bad choice and it’ll often just make things worse. The problem is radio waves, as a rule, don’t go through solid objects. If there’s something in the way then the signal gets from mast to you by a process of reflecting and scattering from neighbouring objects. In practice this means that the signal could be arriving at your device from a multitude of different directions. For that reason a high gain directional antenna, which has a very limited angle of coverage, will frequently make things worse. Unless you have perfect line of sight between the mast and where you are going to mount the antenna then a directional antenna should be avoided. Much better to go for an omni antenna; lower gain but at least it should pick up a signal. Though, to be honest, don’t get too fixated on the gain of the antenna. The antenna in a typical data dongle is less than zero; a LOT less than zero. So even a low gain external omni with 2 or 3 dBi is still several times higher than the antenna in your dongle. The other issue is antenna location. The fact that the external antenna is placed outside (and hopefully high up) is a significant factor in improving the signal.

Conclusion

Single or Dual (or more)

If your dongle or router only has a single antenna connector then go for an external antenna with single connector. If you have a dual stream dongle or router then you need an antenna with two connectors or use two single connector antenna. Note, however, even if you have a dongle and antenna setup that can support a 2×2 service, if the service coming out from your providers mast doesn’t send out 2×2 then you won’t see any different than if you were running a 1×1 set-up.

Correct frequency

As you can see from the Ofcom table previously shown, make sure your antenna setup suits the frequency range of the service coming from your local mast. If you have antenna that only supports 800MHz range but your provider uses a 2.6GHz service then your 800MHz ain’t going to work!
Unless you don’t want to run the risk of having to shin up onto your roof to change the antenna if (when) you change service then it’s best to get antenna which cover all three UK LTE bands. So that’s 800MHz, 1800MHz and 2600MHz. Our antenna clearly specify their operating frequencies and, as I’ve said before, we try to only offer LTE antenna that support all three bands; though you do pay a little more for an antenna with this flexibility.

Omni or directional

My advice is go for an omni. We get a lot of directional antenna back from customers but very few omni types. The reason for this is the customer has just jumped on the antenna which offers the biggest gain for your buck and this invariably means a directional antenna. However most people do NOT have line of sight to the mast so an omni is the way to go.

Location

Mount the antenna where it has the best line of sight to the mast. Even if it doesn’t have true line of site (in a built up area it can often be impossible to see the signal mast) get it as high as possible and  don’t position it so it has to go through a thick wall or metal building located 2 feet away! As an example, if, at our office, we try an outdoor antenna at the front of our building (which is one of those horrible metal boxes you see on industrial estates) then we get a rubbish signal even using an omni antenna. However we try the same antenna at the rear of the building and get almost full signal. The reason is the signal mast is at the back of the building (though still not in true line of sight). Using the antenna at the front means the radio signals have to try and blast a hole through the metal building and that’s just not possible.

Might still be crap

Even if you get a perfect signal then, depending upon the capabilities of your provider (e.g. their frequency allocation), the service they can offer from your local mast, how good your dongle or router is, and how many users are connected to the service in your area, it might still give a rubbish download. However, if it’s just for doing a Facebook post then you probably won’t ever notice!

Steve Mace.

62 comments on “Antenna Considerations for 4G/LTE

  • Steve Mace says:


    Does the router have 2 antenna connections? For the 3/4G I mean. I’d go for the Poynting XPOL-A0001. It’s a great LTE antenna; our most popular unit.

    http://www.solwise.co.uk/4g-antenna-omni-xpol-a0001.html

    Note the antenna has SMA Plugs on the antenna leads. Make sure this matches the connectors on your router.

  • Paul Murray says:


    I would like to say what a great article, very informative and well written. Thank you 🙂

  • John says:


    Hi,
    I note the Poynting XPOL-A0001 aerial as 5 meters of cable, if mounted on the roof it would normally need longer cables, what is the maximum length recommended.
    John.

  • Steve Mace says:


    Any cable of any length is going to reduce the signal. tbh even the standard 5m adds quite a bit of extra loss so our advice is don’t extend it. 5m is normally enough to go from the roof as far as the loft or top floor. We suggest mount the router at that locale and then run a lan cable the rest of the way to another wifi access point placed where you need the wifi.

  • Andrew says:


    Steve, I see the Omni 2dBi gain antenna has suckers for windows.
    My Huawei b593 LTE router is virtually on the other side on the window.
    Is it possible to replace the 5M cables with shorter ones to get maximum gain or won’t it be worth it?
    I’m thinking about 1 – 1.5 metres would do it.
    Thanks.

    • Louise Barrett says:


      The cables are attached to the unit, you can’t change them. You could potentially cut them down though, it may make a small improvement.

      • Andrew says:


        Ok Thanks.

  • Steve York says:


    I have two of your 5db omni antennae. Is there a prime distance between the two for setting up to receive LTE, or can they literally be anywhere on the same roof.
    Thanks for the good educational articles. Keep up the good work guys.

  • Steve Mace says:


    Well I suppose at least a few inches (think of two antenna on a router) but 1 – 2ft would seem good to me. It’s far enough apart to give a spatial separation. tbh it might be worth experimenting though ’cause you want to ensure that both antenna are placed so they each get a good signal.

  • Richard Faulkner says:


    Hi Steve,

    Do you supply something that can capture the 4G signal outdoors, then rebroadcast it indoors i.e. an outdoor 4G aerial which connects to an indoor box with an indoor aerial that re-transmits the signal so any phones or dongle or mifi can receive the signal.

    a bit like this?

    http://www.mobileboosteruk.co.uk/products/sb-1800-mini?utm_medium=cpc&utm_source=googlepla&gclid=CPyq9tKR2sUCFYrKtAod8X4AUA

    Many thanks,

    Richard

    • Louise Barrett says:


      Richard,
      We don’t supply those I am afraid.
      Louise

    • Andrew says:


      Richard, why would you want to do that?
      Those devices are illegal anyway. They re-transmit licensed spectrum.
      What’s wrong with using an LTE router (like my Huawei b593) and using WiFi off that?

  • Fons says:


    Hi,

    I have a question about antenna placement, I have a DWR-921 and have two external antennas.
    The DWR will be used for the LTE internet connection but the WiFi will be disabled and handled by a different router, which will also use 2 external antennas.

    I only have 5m of cable on each antenna and am wondering what the best way to place them is?
    Should I spread them out as far as I can? Is there a minimum distance they have to be placed apart from each other to avoid interference?

    Thanks,
    Fons

    • Steve Mace says:


      Are you asking about proximity of the wifi antenna to the LTE antenna? A foot separation would be fine. If you mean the separation between the 2 LTE or the wifi and antenna themselves then a foot is fine again. However that’s a minimum…. if the aim here is to try an improve reception where there’s iffy line of sight then a wider separation would probably be better. For the outdoor wifi then an all-in-one outdoor AP unit would probably be better than an indoor unit using external antenna. e.g. see out ENS202EXT or similar.

      • Fons says:


        Both actually, I was thinking somewhere around 50cm in between but then realized that I’m just guessing, hence the question 🙂

        I will probably be replacing the WiFi antennas in the next few weeks but I need to have a temporary setup this weekend so this should do fine for now.

        Thanks for the quick answer!

  • Peter Harris says:


    I have seen some higher gain MIMO LTE antennae advertised as ‘vertically polarised’. What are the advantages/disadvantages vs cross polarisation?

    • Steve Mace says:


      Well a true MiMo LTE antenna will have two streams typically separated by differing polarizations. You need to separate the streams somehow. This could be via different frequency but often there’s not enough spare channel space for that. The other way is position, so that’s two antenna separated by distance, a few feet normally suffices. The problem with using this type of separation is you can’t do it in a single antenna package (though I have heard good reports from people that have used two separate antenna rather than a 2-in-1 style). The final way is to use different polarizations for the streams. So you’re hoping that the separate streams will arrive at the antenna with different orientations. Normally the antenna will arrange for polarizations at 90 degrees to each other. So it might be +-45 degrees or vertical+horizontal. I don’t think it matters too much which orientation is used though my gut feeling is the +- 45 degrees MIGHT be better. It all depends upon how the signal is getting from the mast to the antenna and also how it leaves the mast. As far as I’m aware the signal leaves the mast at the same vertical polarization using separate antenna separated by a gap (distance). It would tend to infer then that if there’s line of sight to the mast then two separate vertically polarized antenna would be best BUT if you don’t have line of sight then the signal is getting to the antenna by reflection and scatter. The problem then is each time the signal bounces off a surface it’s reflected at a different polarization. As such when it arrives at the antenna then god knows what the polarizations are of the two streams!

      Anyway a MiMo LTE antenna won’t be just vertically polarized. A true MiMo antenna would be two antenna. So you could have one vertical and the other horizontal but I doubt both would be vertical – not in the same housing anyway.

      • Peter Harris says:


        Thanks for the explanation. The product I was referring to (from another website) is this:
        http://www.3grouterstore.co.uk/3G/Fullband-MiMo-4G-Antenna.html

        • Steve Mace says:


          That would seem to be two vertically polarized antenna in a tube separated by perhaps an inch! tbh I’m not sure an inch or so of separation is enough. I’d think you’d want at least half a wavelength gap which is 3+ inches.

  • john brewster says:


    Hi,

    Thank you for a really useful and informative piece; I would like to buy an antenna to help improve my 4G reception – perhaps you can advise.

    I work in Saudi Arabia and I am looking at the STC mast as I type, its approximately 1.5 miles away and I am on the 3rd floor of an apartment block. I have a Huawei 4G B315s-936 4G router with a 2 x 2 Mimo antennas… And I get less than a 1Mbs download speeds.

    I have a balcony where I can mount with less that 2m cable length needed to mount outside. I cannot drill holes in the walls – diamond tip won’t get through the walls anyway – so the window mount when I get in would be ideal.

    Can you help please?

    Thanks.

    John

    • Steve Mace says:


      The question is though, does this window point in the right direction? Our findings are that unless the window points in even roughly the right direction then an antenna at/on the window doesn’t do much good. With that in mind I’d suggest the Poynting A0001 which is a 4G/LTE dual polarized omni and it has suckers for window fixing:

      http://www.solwise.co.uk/4g-antenna-omni-xpol-a0001.html

      • john brewster says:


        Hi,

        Thank you for the lightening response – appreciated. The only suggestion of Window was due to the mounting… They are actually patio doors to the balcony. I sit on the balcony with a soft drink – of course – and look directly at this huge mast which is giving me poor bandwidth!

        So, u reckon on that model still – I will mount on the door, outside and can “point” directly at the damned thing! 🙂

        Thanks again – really appreciated. If you can just confirm the model, I return to UK on Friday for a week and can take it back out.

        John

  • Darren Tinkler says:


    I am using this on top of a 3 story plant and we are today running with 75ft – 100ft cables from the cradlepoint router to the omni-directional antenna on the roof. Some sites work really well, others not so well. I see comments about 3-5m cable lenghts. None as long as our 100ft (30m). Is there limits on cable length?

    • Louise Barrett says:


      You have to take into consideration the loss in the cable. If you cable has a loss of 15dB based on its length but the antenna you are connecting to is a 5dB then it won’t work. Might be worth you calling in for a chat – 01482 672872.

  • TJ McCann says:


    Hi,
    Really good article.
    I’m wondering if you could recommend a 3G/4G modem router with external antenna? I live in a rural area in Ireland and am on the Vodafone network. I have a huawei r216 dongle. It only receives 3G signal at moment. I am supposed to be in a 4g area but Vodafone say it’s only available outside . So I’m wondering if a new router with external antenna mounted high outside would improve the situation?

    • Louise Barrett says:


      Hi,
      Thank you.
      We offer a range of 3G/4G routers that may be suitable for the job. An external antenna will likely have you see some improvement.
      http://www.solwise.co.uk/3g-routers.htm
      Take a look and see what you think. If you have further questions it may be an idea to give us a ring to discuss or email us on sales@solwise.co.uk

      Apologies for the delay in reply, notifications of comments were not coming through to us.

      cheers
      Louise

  • ali says:


    Hi,
    can you help me to select 4g antenna? I live on area that don’t have Line of Site to mass. but i have 1 of 4 signal on 4g modem. I see new OMNI-291 Antenna in this site. is this a good selection? which is best antenna?

    • Louise Barrett says:


      I would suggest calling sales on 01482 672872 to discuss further.

  • John Brewster says:


    My company is about to start a 5G trial!! Oh hail the 5G – may see the end of cable to the home and business I am told with huge speeds over the air!

    I am trying to get some info… and will let you know.

    http://www.arqiva.com/ – huge infrastructure company – may be worth a read?

    John

  • Ian says:


    Just to advise, we got an Asus 4G-AC55U LTE home router to utilise LTE broadband for our rural house with rubbish ADSL phone line broadband (5Mbps).
    That router has 2 detachable LTE aerials which gave us around 2Mbps with Vodafone but an impressive 15 Mbps with Three, with mediocre LTE reception, even when using the detachable aerials outside.
    Installed the Poynting XPOL-A0001 mentioned above and with a little directional testing, our speed increased to 33 Mbps. An amazing improvement on LTE reception.
    One point to note; we needed the female to female SMA adapters as well to fit the aerial to the router. These really should come with the aerial as they’re needed for one of the main LTE routers on the market. But thoroughly recommend the aerial.

    • Steve Mace says:


      I’m glad this antenna helped you. tbh we strongly advise people use external antenna and I’d guess over 90% of the routers we sill the customer goes for an outdoor antenna. The comment ref. the antenna connectors is very unusual. Normally for LTE the connectors are standard SMA sockets (so that’s thread on the outside and a female pin) so the standard male plug on the antenna leads should be a straight fitment. If you had to use an adapter then that means that this router is very unusual and not standard. We could add some adapters to the kit for everyone but since I’ve never seen any other router that had reverse SMA connectors then that would mean 99% of the customers would end up paying for adapters (because they do cost money) when all they’d do is throw them in the bin or, worse, try to fit them and end up breaking the pin on the connector on the router. However I’ll remember this so if I speak to anyone else that has this router I’ll take care to verify with them exactly what/if adapters are needed. Thanks for the feedback.

      • Ian says:


        No problem Steve and thanks for the comprehensive info on here that helped me make my choice.
        I was alerted to the requirement for the female to female adaptor from a review left on the Broadbandbuyer page for this aerial, who was also attaching it to an Asus router, so perhaps that’s a feature of Asus routers…. https://www.broadbandbuyer.com/products/15383-solwise-4g-xpol-a0001/reviews/#content
        But, a minor point and as said, really impressed with the build quality and real impreovement in the reception. Cheers, Ian

  • Brian says:


    For an LTE USB dongle which spec extension cable should I use, 2.0 or 3.0?

    • Steve Mace says:


      USB2 is fine

  • Jim Stobart says:


    When I bought the 2 Net 3g/4g aerials from you recently it was suggested, I thought (!), that they should be mounted as close as possible which I have done. Reading your excellent notes above it would seem that 1 foot apart is better. Could you advise please? With RUT950 set to 4g mode, I get speeds varying from 5 to 18mb – is this simply congestion or can I make any improvements to aid stability?

    • Louise Barrett says:


      Yes they need to be about a foot apart. They’ll behave very erratically very close together. It may be worth a call to support if you continue to see issues with this.

      cheers
      Louise

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