Omni or Directional Antenna?

The trouble with directional antenna is radio waves will not transmit through solid objects, so if there is anything in the way of the signal reaching the transmission mast then the signal will be interrupted. Unfortunately on narrow boats you are limited with how high you can mount the aerial and are unlikely to know where the mast is when cruising. Many people will automatically opt for a high gain (see section below for further information on gain) antenna, which is often a directional antenna, believing this will provide the best possible service, however unless you have a clear line of sight of the mast this should be avoided.

The other alternative is to opt for a Omni antenna i.e. radiates radio wave power uniformly in all directions. This may have a lower gain, but you are more likely to pick up a signal. The gain rating of the antenna should not be the deciding factor when purchasing an antenna, you need to bear in mind that a typical dongle has a gain of less than zero, so even a low gain external Omni antenna with low gain (2 or 3 dBi) is still a great deal better than the aerial within your dongle.

Be aware that not all external antennas are compatible with all routers/dongles. A mobile router will require an SMA antenna connection whilst a mobile dongle (if it has an external antenna port) a twin TS-9 connector.

Whilst looking for external antenna’s for a narrowboat, you will notice that there is a considerable difference in price. This is often due to the number of antenna connections.

4G is multi-stream MiMo (multiple in/multiple out) technology. One of the reasons that 4G is branded as a faster service to 3G is due to it’s use of multiple radio data streams to and from the end device i.e. the router or dongle. Some cheaper devices will only have one antenna point (known as a 1 x 1 device) which in turns naturally restricts the upload and download speeds. Other devices will have 2 antenna ports (2 x 2 device) which generally support twice the upload and download speeds. The majority of routers and dongles being supplied (generally free of charge) are 1×1 devices, therefore limiting you to 3G upload/download speeds.

If your router or dongle only has a single antenna connection there is no point in paying a premium for a 4G antenna with dual connections as you will not achieve any greater upload/download speed than a cheaper single antenna connection. If you do have a dual connection device then you need to use either two single connection antenna or one dual connection antenna if you want to achieve the maximum upload/download speeds available.

Of course there are other reasons aside from the antenna type why you may not be getting the upload/download speeds you would expect, for instance your service provider/mast must also supports multi-stream to enable to you achieve 4G data speeds. The frequency allocation of your provider will also impact the data speeds and also the number of other users in the area.

Antenna Mountings

There are various mountings available for your external antenna, especially useful for narrowboat users with a steel hull are the magnetic ones. Magnetic ones are ideal for when you are cruising as they can safely be secured to the roof of your narrow boat and can easily be packed away when you are not on-board. Other external antennas are permanently mounted to the roof of your boat, ideal if you specify during the build stage of a new boat. Suction mounts are also available, however these wouldn’t be recommended on a canal boat!

Antenna Gain

Manufacturers rate the performance of the antennas as either dB or dBi; it is not important what this refers to or how it is measured as it is fairly complicated. When comparing external antennas for your canal boat it is important you are comparing like for like. Most antenna manufacturers market their product with the dBi rating because it is 2.15 higher than the dB rating. But if you want to calculate expected results, you need to use dB, if you are considering external antennas with both dB and dBi ratings subtract 2.15 if the manufacture used dBi’s to convert to dB.

As you will know there are various providers of 3G/4G in the UK, including Vodafone, EE, Three etc and you will find that some providers will work better in some areas than others.

As well as needing the right equipment to ensure maximum data speeds, it is also reliant on your service provider and the service they are able to offer. If you are considering purchasing an antenna to improve your 3G/4G data speeds, it is important you get an antenna that is compatible with the frequency band used by your provider.

In simplest terms when 3G and 4G service was launched, the telecoms operators had to bid for their share of the service across three different frequency bands. The implications for the end user purchasing an antenna is to ensure the antenna suits the service provider, or to cover all eventualities, opt for an antenna that covers all three frequency bands.