One of the biggest challenges in the telecommunications industry is to provide best value for money for the client particularly where antennas are required due to the many options, variations and quality levels available.
Powertec Resellers Proeye Communications & Security Systems (Proeye) and CommuniVations, in conjunction with Powertec staff, recently tested two antennas with Cel-Fi Go Repeaters in a 14,000sqm car park.
A Cel-Fi GO is a legal Repeater that has been tested, authorised and approved by Telstra for use on the Telstra Mobile Network. It’s a one box coverage solution for Telstra networks operating on 3G 850Mhz or 4G 700/1800 bands. It is designed to dramatically increase mobile signal to a given area to enable the carriage of voice and data services.
Scott Tracey from CommuniVations needed more coverage for several clients who required mobile signal in large open spaces such as car parks, basements, warehouses and open plan offices. While Cel-Fi GO was the preferred product, the larger area made it increasingly expensive and complicated to install multiple repeaters in such large areas.
Paul Di Berardino from Proeye took on the challenge to come up with a solution to expand Cel-Fi GO coverage while keeping price to a minimum.
To achieve more coverage, Paul had to rethink antenna selection and how RF theory came into play.
A typical low gain omnidirectional indoor antenna disperses signal in all directions in the horizontal plane and about 60 degrees in the vertical plane.
In car park basements low gain omnidirectional antennas disperse the signal in all directions, up, down and all around! Most of the emitted signal reflects and refracts into the ceiling and ground and quickly dissipates away. The net result is coverage of about 40m radius.
High gain directional antennas direct the signal energy to a given area. For example, Panel and Sector antennas project the signal laterally with a radiation pattern of about 35 – 180 degrees, therefore the bulk of the signal is concentrated in that given area. Utilising high gain directional antennas also means that there is less signal bouncing from the ceiling and floor areas which can cause interference too. In theory, the result would be a higher quality stronger direct signal so that coverage from the same Cel-Fi GO repeater would increase exponentially.
Paul felt that the Cel-Fi GO receiver distance can be improved by using high gain directional antennas. He likened it to the way telescopes work as a comparison:
Different types of telescopes handle light particles in a different way to recreate a larger image of the object emitting light, such as a planet, moon or star. Some Telescopes use large apertures to capture and concentrate the light particles and project that image. The larger aperture Telescopes can collect and concentrate more light particles for increased image size and quality.
Antenna theory is similar. Antennas collate and concentrate signals collected from a given area and reject signals from other directions, therefore receiving better quality signals with less interference. Large aperture directional antennas behave similarly to larger Telescopes in that they can garner signals and concentrate them into the repeater for reception, therefore increasing the receive area.
The Cel-Fi manufacturer Nextivity advises that a Cel-Fi Repeater can provide up to 1,200 square meters of coverage, however that measurement is based on an average coverage based on typical installation methods.
Testing the Theory
Proeye approached a Melbourne apartment manager for approval for onsite testing at their premises. They had a 14,448m2 underground carpark with little or no mobile signal coverage which was perfect for testing.
Powertec Telecommunications provided a MARS Dual Stadium Antenna 698-2700 13dBi (ANT-MA-00002) and a Blackhawk Sector MIMO XPOL 698-960 14dBi Panel Antenna (ANT-BH-PN-0001).
Testing was done on smartphone and they were able to achieve 42/15mbps speed tests at 140 meters from the antenna (utilising Telstra 4G 778MHz).
Proeye undertook signal tests and found the following in comparison to the dome indoor antennas before they installed the Antennas.
At 100m the signal was less than -100dBm and not measurable on his spectrum analyser
Once the Blackhawk Sector and MARS Stadium Antennas were installed, there was measurable signal on the spectrum analyser, plus call reliability and speeds were impressive.
The Blackhawk Sector antenna only covers lower bands and was impressive at the lower frequencies providing similar results to the more expensive MARS Panel Antenna. However, at the higher frequencies the MARS Antenna provided better performance (this Blackhawk Antenna only covers lower bandwidths).
The theory about utilising specific antennas to increase signal exponentially was proved with this specific set-up producing more than 10 times the standard coverage by using different antenna designs and concepts.
An outstanding result was achieved by thinking outside the square and utilising antenna variations suitable for specific coverage situations. Powertec offer a range of donor and service antennas designed for use with Cel-Fi products and applications.
Summary of the two Antennas
Blackhawk Sector MIMO XPol 698-960 14dBi Panel Antenna (ANT-BH-PN-0001)
- 14dBi Gain
- Beamwidth Horizonal – 35 Degrees
- Beamwidth Vertical – 35 Degrees
- Port to Port isolation 15dBi
MARS Dual Stadium Antenna 698-2700 13dBi (ANT-MA-00002)
- 12~13 dBi Gain
- Beamwidth – 35 Degrees A & V
- Port to Port isolation better than 22dB -22 @ 698-960; -37 @ 1700-2700
- Beamwidth and Azimuth was 35 Degrees
For more information on these antennas and other options to extend cellular coverage, contact Powertec on 07 5577 0500 or email [email protected].