AWR Application Notes

AWR Software for the Design of MIMO and Phased Array Antenna Systems 4 www.cadence.com/go/awr To demonstrate some of the capabilities of the phased array model, an example project was constructed showing two 15x5 element arrays operating at 2.99GHz (Figure 4). Figure 4: Two 15x5 element phased arrays based on isotropic and patch antenna radiation patterns with theta angle set to 15° One model represents an array of lossless isotropic antennas defined simply by setting the antenna gain to 0dBi, while the elements of the other array utilize a data set containing the radiation pattern of a single simulated patch antenna. Both arrays use a lattice configuration with a 1/2-wavelength spacing between elements and uniform gain tapering, explained in more detail below. For the simulation shown, the steering angle (theta) was set to 15°. Note that the antenna and phased array blocks support specifying the signal direction using U/V coordinates as well as theta/phi angles (Figure 5). Figure 5: Radiation patterns for 15x5 and 30x5 arrays and side-lobe behavior for array (5 x 15) The AWR VSS array model provides antenna designers with a rapid and straightforward tool to observe key antenna metrics, providing a means to examine the main beam and side lobe behavior as a function of any number of variables, including array size and configuration, gain versus steering angle, and the occurrence of grading lobes as a function of element spacing and/ or frequency. From these results the array design team can develop an optimum configuration for the given requirements such as range and overall array physical size. In addition, the team can provide design targets for the individual antennas and incorporate subsequent antenna simulation results back into the array analysis. Changing the amplitude excitation through gain tapering is often used to control beam shape and reduce the side-lobe levels. A number of commonly used gain tapers are implemented in the phased array block. Gain taper coefficient handling defines whether the gain taper is normalized or not. If it is, the taper is normalized to unit gain. Standard gain tapers implemented in the phased array model include Dolph-Chebyshev, Taylor Hansen, and uniform. The earlier example (5 x 15 element patch array) was re-simulated with uniform versus Dolph-Chebyshev gain tapering to understand the impact on the main beam and side lobes, as shown in Figure 6. In addition, the user can define custom gain tapers by specifying the gains (dB) and phases for each array element. Figure 6: 5 x 15 patch array with uniform vs. Dolph-Chebyshev gain tapering

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