California Highway Patrol Radio Communications System Wideband, Lowband Rugged Antenna Solution

October 2, 2018, 9:21 am

The California Highway Patrol’s (CHP) mission is to provide the highest level of safety, service and security to the people of California. As the largest state police agency in the United States, the CHP serves a large geographic area.

In 2010, CHP began a five year project (CHPER’s project) to improve and enhance their current statewide 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 a high quality wideband lowband antenna on all patrol cars. The CHP had previously used Laird’s narrowband lowband antennas ontheir patrol cars. Because of the existing relationship between Laird and CHP, CHP approached Laird to assist in finding a solution that would meet their needs. The original idea was to use a standard product tuned to a different frequency. However, it was soon determined a standard product would not meet all of the requirements necessary for CHP’s new system and frequency assignments. CHP and Laird were challenged to develop a new wideband antenna solution that could meet all of the requirements.

Situation

The California Highway Patrol had many requirements for their new antenna. Having a single antenna to cover the entire CHP 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, CHP 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 CHP’s 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 of CHP’s 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 CHP’s 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. However, due to the extreme conditions and the need to dissipate heat generated from CHP’s 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

The California Highway Patrol 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 CHP.

Due to the CHP requirements, 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 both CHP 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.