Mobile Device Design
Precision is key when designing today’s complex mobile devices, so engineers cannot afford discrepancies between device efficiency and simulation results. Starting with detailed CAD model import, XFdtd computes efficiency results that match measurements with less than 0.5 dB difference. Further, advanced features streamline the workflow for designing antennas under multiple operating conditions. Below are highlights from the design process in XFdtd.
Wrap for Flexible Circuits
Wrapping is essential for simulating flexible PCBs because leading layout tools produce a flat design. Without efficient simulation software, manually adding multiple bends is a painstakingly slow process. To replicate the physical model, XF’s wrapping capability supports full, multi-layer flexible PCBs during import, eliminating the need to wrap individual layers and parts manually. Simply select the PCB file from the Import menu, provide the form, and let XF wrap the PCB automatically.
CTIA and Poseable Hands
Complying with measurement standards and meeting performance expectations requires versatile antenna design software. By supporting both CTIA and Poseable hand models, XF simulates cell phone use scenarios for successful device design. CTIA models easily grip the phone for handheld and next-to-head operation, and Poseable Hand models offer numerous other orientations to mimic real-world positioning.
Many configurations need to be tested during the design iteration phase -- this is necessary for a thorough antenna analysis -- but setting up each configuration manually can be a repetitive and time consuming process. A successful production environment requires automation and a customized workflow to maintain efficiency.
Project setup can be automated to include the following options:
- Include/exclude hands, head, and other parts in the mesh
- Create simulations for main, diversity, GPS, and Bluetooth antennas
- Set the frequency range for different antennas, including the waveform
- Enable output requests and set DFT frequencies
Automation also applies to data export. XF can consolidate data -- S-Parameters, impedance, radiation, and system efficiency -- from multiple simulations and export it to a spreadsheet.
A mobile device is only as good as its wireless connection, so it is necessary to quantify antenna diversity within the EM simulation. XF considers field polarization and direction when computing complex correlation and mean effective gain outputs. This allows XF users to evaluate the quality and reliability of a device’s antenna system and then improve the design’s performance to capture the strongest wireless link in multipath situations.
Specific Absorption Rate (SAR)
Complying with FCC standards is a requisite part of mobile device design that demands reliable EM simulation software. In addition to single antenna operation, XF has the ability to combine SAR results when there are multiple antennas operating in the same frequency band to get the total 1g and 10g SAR values. This allows engineering to keep power levels below the specified threshold and ensure a device performs within regulations.
Full-Wave Matching Circuit Optimization (FW-MCO)
Determining the layout is only part of the matching circuit design process. Component values must then be selected with consideration to the actual antenna’s properties to ensure the design accepts a signal. Modern matching circuits include traditional RLC and tunable components, which presents a unique challenge when choosing a specific component to place in a matching network.
The FW-MCO method takes the guesswork out of choosing component values by assessing the antenna’s properties and evaluating thousands of possible component combinations. It selects optimal values based on the user’s defined goals and thresholds, generating an efficient matching network. FW-MCO utilizes XF’s Circuit Element Optimizer feature.
XF’s capabilities are the keystone of a comprehensive antenna design process that continues with indoor modeling. Wireless InSite supports XF’s radiation patterns as input and offers full control of defining a wireless environment. The ability to import files, create objects, and edit a floor plan ensures a realistic simulation, and site-specific placement of the transmitter helps to assess the device’s received power.