Public Safety Antenna Co-Engineered to Withstand High Power and Dissipate Heat

October 2, 2018, 9:20 am
Public Safety Antenna Co-Engineered to Withstand High Power and Dissipate Heat

In 2010, a major government public safety agency set out to improve and enhance their current radio communications system. In order to continue to carry out their mission, improved interoperability between regions was necessary.  In cases where units from multiple regions were deployed to support an incident, a need for frequency pairing operating on wide spacing was crucial to minimize interference.  A vital part of this project was increasing the separation between transmit and receive frequencies which then required the installation of high quality wideband lowband antennas.

The agency previously used Laird’s narrowband lowband antennas. Because of the existing relationship, they approached Laird to assist in finding a solution that would meet their current needs. The original idea was to use a standard product tuned to a different frequency. However, it was soon determined that a standard product would not meet all of the requirements necessary for the new system and frequency assignments.  Laird and our customer were challenged to develop a new wideband antenna solution that could meet all requirements

Situation
This particular public safety agency had many requirements for their new antenna. Having a single antenna to cover their entire lowband frequency pool was important.  In addition to serving a large frequency range, the antenna had to withstand extreme environmental conditions ranging from high heat to strong wind applications.  Maintaining communication in a high wind/pursuit scenario was critical.  To ensure the antenna would perform in this challenging environment, they required the antenna to operate with low VSWR and full power while deflecting at 90 degrees.  The new antenna also had to pass a power test which pumped 100W of power into the antenna for 10 minutes, without failure.

The challenge with these requirements was the combination of a wideband and lowband antenna that would also pass the power test requirement. Laird’s existing antenna designs, patents and expertise enabled the team to create a wideband solution that met all frequency requirements. The true challenge came when designing an antenna that could reliably withstand the power test and maintain a low VSWR when deflected 90 degrees.
 
Solutions
Laird Wireless Systems engineering team, located in Schaumburg, IL, was tasked with creating a solution to meet the design requirements.  Initial assessment of the current antenna design required the development  of an antenna with improved ability to withstand high power and dissipate heat.  It was clear that the team would need to address some of the thermal issues created during the power test.

To combat the heat issue, the Laird team made two major changes to the initial antenna design, resulting in the development of the WPC39S0B-001, Wideband Lowband Antenna.  First, the original design used a very robust high impact PC/ABS plastic housing.  This high impact material is used in a majority of Laird’s mobile antenna products as it is RF friendly and has proven to withstand the harshest of environments.  Due to the extreme conditions and the need to dissipate heat generated from the power test, Laird changed the material design to a new and improved metallic housing.  This was the most favorable material to use for heat transfer and dissipation and is also a great material to use for outdoor environments requiring weatherproof solutions.

Secondly, because Laird is a leader in the design and fulfillment of a diverse group of electronic products and components, the team was able to enlist experts from the Laird Performance Materials division to further address the thermal issue.   High-performance soft gap filler, Tflex™ 700, was introduced into our antenna design to assist with heat dissipation.  This thermal interface material draws the heat from the internal components of the antenna and transfers it to the outer metallic housing to help remove the heat created by the high power test.  The Tflex™ 700’s performance, thermal properties, ease of use in manufacturing and reduced stress on components in an RF environment made it the ideal material to complement our design.

Conclusions
This antenna project highlights Laird’s expertise in developing high-quality solutions for the public safety industry. The team from Laird was able to design, test and develop a solution that met all of the requirements set forth by our customer.

Laird antenna experts developed a solution that would perform at the necessary frequencies and would reliably withstand the power test and maintain a low VSWR when deflected 90 degrees.  By collaborating with our customer and Laird’s thermal materials experts, the team incorporated a metallic housing with Tflex™ 700 to help dissipate the heat and allow the WPC39S0B-001 to pass the power test and still meet the frequency requirements.

Experts from across Laird’s diverse product portfolio collaborated together to create an original industry- leading solution for our customer.