A new SmartWatch design presented an opportunity for Taoglas to work closely with one of their customers to provide a highly innovative solution to the wearables industry. The challenge was to integrate two high performance and efficient antennas within the compact, low profile wearable device. The first antenna was a 1575MHz GNSS antenna to provide personal positioning information, the second antenna was a 2.4GHz Bluetooth antenna to be used for data communications.
The first stage of the design involved modeling the physical device in 3D and selecting the optimum LDS polymer resin. Taoglas used Solidworks® to clearly define the 3D structure, communicate with the customer and to ensure that the antenna could be implemented within the planned product construction.
As this was a wearable application the LDS polymer resin selected was a Polycarbonate [PC]. Polycarbonate is one of the many LPKF approved* LDS polymer resins available. Below is a list of the popular LDS resins that can be used:
Once the physical design is finished and the correct polymer resin selected, the basic antenna designs could begin. For full antenna modeling, Taoglas used CST Microwave Studio®. The two antennas were designed to fit on the surface of the of the plastic part (see figure 2). This plastic part is commonly referred to as the antenna carrier. The antenna carrier, in the case, had an outer radius of 38mm and a height of 3.2mm which provided a very compact solution. The carrier was also designed to snap fit into the watch outer casing and to provide simple connection points to the main electronics board [PCB].
Modelling of the design in CST allows for design adjustments and antenna optimisation without the need for “trial and error” sampling which, in turn, reduced cost and lead-time for the overall design.
(LDS Antenna locations and layout) Figure 2
(LDS Antenna locations and layout) Figure 2
Below are images of the optimised radiation patterns developed within CST (figure 3).
The first production representation samples of the SmartWatch frame were manufactured using the Taoglas LDS capability in Taiwan. The MicroLine 160i LDS laser (see figure 4) can be quickly configured to precisely transfer the antenna pattern from CAD data onto the surface of the first molded carriers.
Once the antenna pattern has been completed the activated areas of the part are metalized using an electroless plating process. The electroless plating process used deposits a minimum of 12um of Copper followed by 4um of Nickel.
Taoglas was able to provide the customer with two highly integrated and efficient antennas on a single antenna carrier. The antennas performed well within this low profile, compact device. The LDS solution, that Taoglas provided, easily outperformed traditional approaches because the antennas could be placed at locations furthest away from the active electronics. Due to space limitations, traditional antennas are difficult to use and impact on space and performance requirements. LDS allowed the antenna patterns and associated performance to be optimised quickly. Minor changes to the antenna design and pattern were implemented immediately without cost and without the need for expensive tooling modifications. This product once finished ramped up quickly into volume production.
