AWR Application Notes

Addressing 5G and MIMO Design with Circuit/Antenna In-Situ Simulations with AWR Software Cadence is a pivotal leader in electronic design and computational expertise, using its Intelligent System Design strategy to turn design concepts into reality. Cadence customers are the world's most creative and innovative companies, delivering extraordinary electronic products from chips to boards to systems for the most dynamic market applications. www.cadence.com © 2020 Cadence Design Systems, Inc. All rights reserved worldwide. Cadence, the Cadence logo, and the other Cadence marks found at www.cadence.com/go/trademarks are trademarks or registered trademarks of Cadence Design Systems, Inc. All other trademarks are the property of their respective owners. 14720 06/20 SA/RA/AN-M-INSU/PDF Examples of the antenna pattern are shown in Figure 6. The beam is steered by controlling the relative phasing and attenuation to the various transmit modules. In practice, the harmonic balance takes substantial time to run with 16 power amplifiers. Therefore, the beam is steered with the amplifiers turned off. The designer then turns on the power amplifiers for specific points of interest. Note: Figure 6 (right) shows a second lobe created when the main lobe is at a near grazing angle. Figure 6: The beam of the array as it is scanned through typical values of theta and phi This second example is an 8X8 patch array. Anything that can be tuned in AWR Microwave Office can also be optimized. For example, in Figure 7, the antenna pattern is optimized for a certain scan angle. In the interests of time, the amplifiers are not included in the optimization. At the end, the amplifiers are turned on to see the amount of degradation. The plot is of the total power in the beam, scanning in the theta direction with phi at 0 degrees. The blue bars show the optimizer goals for the measurement. The purple pattern is the original broadside pattern. The optimizer changes the phase and attenuation at the feeds to the patches. The resulting blue curve meets the optimization goal of scanning at 20 degrees with acceptable side lobe levels. Figure 7: The antenna pattern is optimized to be below the blue bars Conclusion In conclusion, designing antennas with multiple feed points for communications or radar systems requires simulation of the interaction that occurs between the circuit, typically a highly nonlinear power amplifier, the feed network, and the antenna. The beam is steered by the circuitry, and as the beam changes the input impedance or input characteristics of the antenna change, which effects the circuit. The circuit and the antenna are connected, so both must be included in the simulation. The traditional method of simulating antennas with multiple feeds is to simulate the coupled antenna/circuit effects manually using an iterative process that is time consuming and frustrating. AWR Microwave Office circuit and antenna simulation are coupled together, enabling arrays to be easily excited from the amplifier and feed network. The load impedances of the array are incorporated into the circuit simulation. This automates the process, saving design time and delivering products to market faster.

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