Cone vs Beach Ball – When to Choose an Access Point with an External Antenna
In the world of wireless access points, one size does not fit all. There are choices to be made in ensuring that you have the best technology fit for the requirements of each situation and one of the key considerations is whether to use an Access Point with an internal or external antenna. So how do you choose? What are the situations where an external antenna provides benefits over the more common internal antenna? We’ll examine some typical scenarios where an external antenna could be the right solution.
But first, let’s clarify the difference between internal and external antennae. It’s primarily to do with the propagation, or radiation patterns – that is, the directional variation in the intensity of the radiation from the antenna, or in simple terms the range and strength of the coverage.
Propagation patterns can be broadly categorized as omnidirectional (usually simply called omni) or directional. An omni propagation pattern delivers evenly spread coverage in all directions from the antenna, often described as having the shape of a beach ball. A directional propagation pattern sends the signal downwards and out, resembling the shape of a cone. The beach ball pattern delivers a signal with a wider spread, but less strength. The cone pattern swaps breadth for strength.
Secondly, however, using an external antenna allows the AP and its antenna to be mounted separately. There are some situations where, due to temperature or humidity, for example, you cannot have an AP, but where you might need coverage. By separating the two elements, you can protect the AP from harsh conditions, but still have the antenna optimally placed.
How does propagation pattern relate to internal and external antennae?
Internal antennae only deliver an omnidirectional pattern, whereas external antennae offer a range of directional patterns. They give you far more control over shaping the exact pattern of the coverage that you need, with a growing range of specialist antennae on the market to meet the shape you need for the most challenging radio frequency (RF) environments.
When to consider external antennae?
Warehouses have a number of RF challenges. Firstly, the ceilings are high, so the coverage from an omni antenna may not even reach the ground, where the workers are using their wireless devices. Secondly, a warehouse is divided into shelving and aisles. The signal is needed only in the aisles, not across the whole warehouse space. Thirdly, the shelving in a warehouse is usually made of metal, which can distort the shape of the antenna’s propagation, making it ineffective.
Using directional, external antennae allows the warehouse operator to have APs that deliver coverage right to ground level (even if they are mounted on the ceiling), that sends a signal down the aisles only and which avoids and is therefore not affected by the metal shelving.
The configuration of metal shelves and aisles described above also applies to some retail stores – particularly supermarkets/hypermarkets, mass merchandisers, retail warehouses and DIY superstores. So here too, a directional, external antenna allows the signal to be directed to where it is needed and not broadcast across the whole store area.
For organizations with large chilled storage operations, there may well be the need for wireless coverage inside the units. Low-temperature environments are not good for an AP, but an antenna can operate with no issue. Using an external antenna allows you to mount the AP itself outside the chill facility and the antenna inside.
Many organizations need to offer coverage across external areas – schoolyards, ports, docks and logistics companies with outside storage areas for example. Protecting an outside access point from the weather may not be feasible, so an external antenna allows the AP to be protected inside, with just the antenna outside.
Areas that are very highly densely populated need a particularly strong coverage to be effective. An arena, filled to capacity for a sporting or music event, for example, has a very large number of people in a relatively small space, all wanting to use wireless devices. An external antenna, with a directional pattern covering the seating areas only, offers a far more effective solution than an omni-internal antenna.
Wireless access is now an integral part of so many places, whether for business or leisure. Many of them really benefit from the flexibility and adaptability of the directional antenna to deliver the best possible signal, exactly where and only where it is needed.
Learn more about Aerohive’s portfolio of access points on our website.