The selection of an Access Point is very important when it comes to satisfying a specific design and coverage requirement. Also equally important, is choosing the right antenna.
Integrated antenna access points provide coverage, and serve a variety of applications, but can be limiting in certain environments.
In this blog, we’ll compare internal antennas to external ones, walk through a few specific use cases, and discuss best practices for installation and success.
Limitations of internal antennas
APs with internal antennas usually have an omni-directional coverage pattern. This coverage pattern is fixed and only varies depending on the orientation of the mounted AP. Typically the AP will be mounted on the ceiling with most of the radiation propagating downwards. In almost all indoor deployments, such as offices, schools, hotels, etc., ceilings mounted APs with internal antennas provide adequate coverage and satisfy aesthetic requirements.
Benefits of using external antennas
When deploying external antennas, more control is gained over the energy radiated. Compared to internal antennas, which have fixed coverage patterns, external antennas can tailor the shape based of coverage needed — to meet the most challenging design requirements. Think of large open areas or areas that require high-density applications. With an external antenna, one can mount the AP and the antennas separately, protecting the AP from harsh environmental conditions. External antennas are also beneficial for reducing CCI by ‘shaping’ the RF. Whereas the internal omni-directional antenna APs end up propagating signal coverage in all directions. External antennas also carry a smaller price point, versus an access point. With the flexibility of external antennas, often times, changing an external antenna may be all that’s needed – which ends up saving you money.
Use cases where external antennas would be beneficial
Choosing the right external antenna also depends on the use case.
Designing Wi-Fi network for warehouses presents unique challenges. They are all about open spaces. narrow aisles, and high ceilings (usually ranging from 25 feet to sometimes as high as 80 feet). Omni-directional antennas perform well up to 25 feet, however, beyond 25 feet, the received signal strength of handheld devices such as barcode scanners is poor and may not be detected. Warehouse designs vary for different heights. Varied coverage may be required for the aisles, but not over the entire area. It’s also worth noting that high metal racks, inventory and volume of product can all impact attenuation. In addition, other dynamic challenges to consider, such as heavy machinery and moving warehouse vehicles, can also impact coverage and network performance.
High ceilings also result in very limited options for mounting APs. Use of directional antennas allows focused coverage in narrow aisles of the metal racks and also helps get coverage all the way to the ground, even if the APs are mounted on the ceiling.
Many environments require outdoor coverage, such as college campuses, parking lots, schoolyards, etc. Using external antennas can be beneficial because it enables the APs to be placed inside and protected from theft and weather-related damage. Thus, only the antennas need to be placed outside where coverage is necessary. Using a patch or directional antenna, allows you to design coverage in more areas where it’s needed.
Having a large number of people, seated closely together in an auditorium/stadium, can make designs very challenging. Sporting events or a concert fills the arena to almost full capacity and all users want Wi-Fi coverage for their devices. Using an external antenna, with high gain, and a highly directional coverage pattern, can be used to intentionally provide coverage to the seating area only. This is not quite possible when using internal antenna APs.
- Install the APs and antennas at an optimum height; to achieve good coverage while being safe from accidental damage.
- Do not mix and match antenna type connected to a single AP.
- Make sure the antennas orientation and alignment is correct in order to achieve optimum coverage and data rates.
- Avoid placing APs and antennas near metal beams or in metal cases to prevent blocking the signal.
- Avoid long cable runs to mitigate cable losses.
- Use external antennas under suspended ceiling and the AP above the suspended ceiling.
Key Steps for Success
- Use Ekahau Pro to do a predictive design.
- Follow up with a pre-deployment site survey – AP on a stick.
- After installation, verify the results with a validation survey.
Want to learn even more about external antenna APs? Watch Ekahau’s webinar below for a discussion on when to use an external antenna AP and why it can be critical to your design.