Improved in-building wireless coverage will take center stage as users clamor for reliable wireless coverage. Ceiling Mount Antennas will be an important aspect of this push for ubiquitous coverage.
In building networks are likely to be either WiFi networks or Cellular networks. WiFi networks will typically originate within the building. The main access point may be sufficient to cover the building or it may need to be supplemented with a network of wall or ceiling mount antennas within the building. In-building networks on Cellular frequencies need to bring the signal in from outside the building. Various repeater set-ups are available to bring the signal into the building. The challenge then is to disperse the signal in an efficient manner.
There are different antenna styles that can be incorporated into either a building retrofit or a new construction project. The goal is to find the balance between ease of installation and coverage area.Since Mobile Mark area of expertise is antennas, this white paper will outline some of the wall mount and ceiling mount antenna styles available for in-building wireless coverage.
For large area coverage or for directional coverage, a wall mounted antenna might be used instead of a ceiling mount antenna. Corner Reflector Antennas or Panel Antennas are available to shape and direct the wireless signal. The coverage pattern will be determined by the gain of the antenna. The higher the gain the further the signal will be thrown but the narrower the coverage. This type of focused coverage can be used to ensure optimal coverage in open areas or in long corridors.
A number of wireless site survey software packages are available to help map out the appropriate coverage for a given building. They allow the user to examine the coverage obtained from antennas of different styles and gains.
Many rooms and meeting areas can be optimally covered with small omni-directional ceiling mount antennas. These antennas are typically rated from unity to 5 dBi gain and designed to provide balanced coverage within a confined space.
It is important to find the right balance. The lower the gain of the antenna the wider the radiation pattern exhibited, while a higher gain on the antenna will boost the Effective Radiating Power (ERP) of the wireless system. There are practical limited to how much gain is desirable in a confined in-building application. Antennas at higher gain would manifest a narrow beamwidth which would severely limit the radiation directly below the antenna.
In some cases, wireless coverage can be achieved with small device rubber-duck style antennas that are used as ceiling mount antennas since they are mounted in the ceiling. Half-wave antennas are preferred over quarter-wave antennas because they do not require a metal ground plan for peak operation.
The size of the antennas will vary by frequency. For Cellular applications at 850/1900 MHz a half-wave device antenna will typically measure 8-inches in length and for WiFi at dual 2.4/5 GHz the antenna typically measures 4-inches. Most rubber-duck style device antennas measure -inch in diameter and this profile is usually considered slim enough from an aesthetic point of view to compensate for the length.
These antennas are vertically polarized so it is important to mount them vertically. They can be mounted either pointing downward from the ceiling or if they are mounted in the crawl space above the ceiling they can be mounted pointing upward or downward.
Other
Ceiling Mount Antennas styles are available in various shapes from flat panel to rounded dome. Examine the needs of the wireless network in determining the style that is right for the network. For example, the options might be different depending on whether the network is envisioned strictly as a WiFi network or if it is envisioned as a repeater network for Cellular coverage. WiFi networks will operate strictly on 2.4 GHz or on dual 2.4/5 GHz depending on the generation of the protocol (i.e. whether it is an 802.11g or 802.11n network). In either case, the physical size of the ceiling mount antenna will be lower for WiFi applications than for Cellular applications.
US cellular networks have operated, for years, on the 850 & 1900 MHz frequency bands, but that is starting to change. A number of Carriers are expanding their coverage onto new frequency bands won in various spectrum auctions. AT&T and Verizon are rolling out 4G systems using the 700 MHz band for LTE T-Mobile, Cricket & MetroPCS are using the AWS bands at 1.7 & 2.1 GHz. Clearwire/Sprint Nextel is offering WiMAX coverage at 2.5-2.7 GHz to supplement its Cellular offering.
Sometimes it is possible to know exactly which frequencies will be employed by the Cellular Carriers in the area. Buildings, unlike vehicles, have the advantage that they are fixed in place and so it might be possible to anticipate which specific frequency bands will be used in a give location. If this is possible, then repeater ceiling mount antennas can be selected for these specific frequencies.
However, if multiple Carriers are in operating in the region on different frequency bands, then if might be useful to select a wideband ceiling mount antenna. that operates on multiple frequencies. This way the network designer is prepare for whichever phone system the wireless user brings into the building.
There are many factors to consider in planning out an in-building wireless network. The wall mount or ceiling mount antennas are a small but important piece of the puzzle. Selecting and locating the right antennas can make big difference in achieving balanced and thorough coverage. These factors are not always apparent to the wireless user but they can make a big difference in the wireless experience.
