External antenna information

A key feature of many car cradles that we supply – the ones with integrated antenna couplers by Bury, Carcomm and Strike – is to boost mobile phone reception, thereby increasing call quality and decreasing the number of dropped calls. Users experience better performance on their phone signal (because the available outside signal gets transferred to and from the phone inside the vehicle) when using their smartphone in one of these cradles when it is connected to a suitable antenna. The success of this depends on the many factors that affect mobile phone reception.

Of course in most urban and regional areas where the signal is strong and steady, it’s not necessary at all to use the antenna coupling function of the cradle, and in fact many of our users don’t bother to connect the cradle’s antenna lead (it’s about 20cm long with a connector on the end) at all, and some even cut the cable off the cradle altogether. So they just use the cradle’s excellent holding and charging functions. If you are in that category, no need to read any further, but if you do want to maximise weak or uneven mobile reception, read on…

First of all, please make sure your cradle is connected to a suitable antenna. If not, then antenna boosting cannot work, or will work poorly. We recommend Strike or RFI branded antennas. If it is not a Strike or RFI antenna supplied by us then we can’t predict performance, as we don’t know the quality of the antenna or the frequencies that other antennas might be tuned to.  We also suggest that you check that – if a bullbar-mount antenna – the antenna is securely mounted, with earth connection to bare metal if possible, and also that the FME screw connector between the antenna’s cable and the cradle’s antenna lead is firmly tightened.

Note that in many cases, especially when signal is relatively strong, the phone’s display will not provide any visual sign of antenna boost such as more bars of signal; this is considered normal as the number of bars only shows “relative” signal strength and are not a reliable or even consistent indicator. So it’s not practicable to evaluate the reception performance of the phone/cradle/antenna if it is already in a strong or stable signal area; and in fact the cradle/antenna combination may make very little difference in this situation anyway.

Doing a field test on most mobile phones is also not an accurate way of measuring signal boost. In test mode they can display “potential” power delivered to the phone antenna that is measured in negative dbm, but the real figure can be different.

So the only real way of checking how well the phone/cradle/antenna combination is performing is to try it out in actual conditions, preferably where you may have previously experienced reception problems, and see whether there’s an improvement in call quality and number of dropouts.

The following can directly affect phone/antenna performance:

  • wind
  • humidity
  • rain
  • cloud cover
  • UV radiation
  • the surrounding environment (see below)
  • other devices
  • phone positioning
  • antenna positioning
  • proximity to and positioning of buildings or metallic objects.

This is impossible to replicate, and thus it is impossible for us to predict or guarantee performance, or to test accurately at any other location in any other conditions.

Factors Affecting Mobile Phone Reception

1. Distance and Direction of the nearest mobile phone tower

You must be within range of a mobile phone tower and the range can vary depending on the transmission power of the tower as well as the transmission power of the mobile phone. This is why different phones can have vastly different call quality.

2. Transmission Power

The transmission power of the phone tower is always greater than the transmission power of the phone, which could mean that you have multiple bars on your phone yet you are unable to carry on a conversation. In this case you may be able to receive but unable to transmit, leading to poor call quality.

3. Environment

Environmental factors such as geography can affect coverage as a signal that has a direct line of sight with a cell tower will be stronger than a signal that is having to go through obstacles such as mountains, buildings, trees etc. Even the time of year can affect reception, as in summer there will be more foliage on trees than in winter which can lead to decreased signal. Some materials that signals encounter, such as metal, may reflect or block signal. And varying weather conditions such as thunderstorms, rain, even wind strength and direction, can also affect signal quality.

4. Network Congestion

Busy towers will drop calls and diminish quality, as towers have a finite amount of capacity.

5. Antenna Efficiency

The efficiency of an antenna relates the power delivered to the antenna and the power radiated or dissipated within the antenna. A high efficiency antenna has most of the power present at the antenna’s input radiated away. A low efficiency antenna has most of the power absorbed as losses within the antenna, or reflected away due to impedance mismatch.

Efficiency is one of the most important antenna parameters. It can be very close to 100% (or 0 dB) for dish, horn antennas, or half-wavelength dipoles with no lossy materials around them. Mobile phone antennas, or wifi antennas in consumer electronics products, typically have efficiencies from 20%-70% (-7 to -1.5 dB). The losses are often due to the electronics and materials that surround the antennas; these tend to absorb some of the radiated power (converting the energy to heat), which lowers the efficiency of the antenna.

The higher the percentage of the efficiency the better the antenna is.

6. Antenna Gain

The term Antenna Gain describes how much power is transmitted in the direction of peak radiation to that of an isotropic source. Antenna gain is more commonly quoted in a real antenna’s specification sheet because it takes into account the actual losses that occur. An antenna with a gain of 3 dBi means that the power received far from the antenna will be 3 dB higher (twice as much) than what would be received from a lossless isotropic antenna with the same input power.

Notionally, the higher the dBi rsating the better the antenna is.  However antenna length also affects performance.  In hilly or regional patchy-signal areas, a shorter antenna with lower gain will generally outperform a longer antenna that has higher gain.  Conversely, in remote and flat areas where the tower is a further distance away, a longer /higher gain antenna will perform considerably better.

7. Available Signal

A mobile phone cradle and antenna will not boost a signal that is not there. A phone must be within transmission and reception range of a tower to successfully carry on a call.

8. Carrier Network

The network that the phone is using can affect signal availability and/or strength. Although Telstra is generally agreed to provide the widest coverage, some other networks may have limited or no coverage in remote areas and as such an antenna and cradle cannot assist, given that it is impossible to boost zero signal. In outback and regional areas 3G and 4G are the most widespread frequency bands (although 3G is now being phased out), and 5G is more commonly available in towns and surrounds.

9. The mobile phone itself

Even though the cradle incorporates an internal antenna coupler to move the signal between the phone and the antenna, its performance depends to some extent on how good the phone’s internal antenna is, and where it is situated inside the device, Even though designers of modern smartphones work hard on improving internal antenna efficiency, the constraints of size (especially thickness) and shape dictate that often the antenna is physically less capable than older phones. Inevitably, some brands and models are better or worse for this than others.

It’s also important that the phone’s cellular band is tuned to the antenna you are using. If it is set on “Automatic” band selection, and it sees that a certain band is available, it will keep trying to use that band even if the antenna is tuned for a different band. If you suspect that this might be a problem, try going into the phone’s settings and changing the band it is looking for.

[We acknowledge much of the above content which has been supplied by Strike]

These are the two antenna connectors you will be using if you have an external antenna.  The connector on the left is on the end of the cable (between 1m and 10m long depending on the antenna type/model) coming from the base of your external antenna, and the connector on the right is the one that is on the end of the antenna lead (about 20cm long) coming from your cradle. These two connectors screw into each other.

‘The Guardian’ 9 October 2021:

Mark Gregory [RMIT University] said 2-10 mbps represented a very low download “throughput”, a term related to the data capacity being put into the network, explaining why consumers may find mobile phones unreliable in some rural and regional areas.

“It’s not their device and it’s not the local impairments, it’s a capacity problem,” Gregory said.

“We’re talking about 4th-generation [4G] technology that’s capable of hundreds of megabits per second.”

Penn [Telstra CEO]  said there was a large volume of additional traffic on our network across Western Australia which could not be immediately “remedied”.

Penn cited Exmouth, which had a fourfold increase in network traffic over the same time last year, as an example. He said the company had a number of planned projects to upgrade the network capacity to improve the “end user experience”.

A spokesperson for Telstra said Penn had outlined a number of different factors that might be impacting the speed range, including the number of users, proximity to the serving mobile tower, the type of device used and environmental issues such as terrain and even building materials.

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