This chapter provides an overview of synthetic-aperture systems for applications related to wireless communications. By sampling the fields propagating through a spatial volume at many locations, synthetic-aperture-system measurements allow the reconstruction of the temporal and spatial characteristics of the channel in post-processing. While often used to characterize spatially diverse multipath environments, synthetic-aperture systems can also provide reference measurements for assessing the over-the-air (OTA) performance of a wireless device under test (DUT).

Chapter Contents:

• 11.1 Synthetic-aperture methods
• 11.1.1 Prior work
• 11.1.2 The role of the spatial Fourier transform in synthetic-aperture processing
• 11.2 Beamforming and measurement attributes of synthetic apertures for wireless communications applications
• 11.2.1 Array coordinate systems
• 11.2.2 Beamforming and angular resolution
• 11.2.3 Beamforming measured S21 data
• 11.2.4 Effect of element pattern on beam steering
• 11.2.5 Frequency invariant beamformer with reduced sidelobes
• 11.2.6 Bandwidth effects
• 11.2.7 Delay resolution
• 11.2.8 Total received-power delay spread
• 11.2.9 Dynamic range
• 11.2.10 Using system parameters to design a synthetic-aperture system
• 11.3 Measurements and uncertainties
• 11.3.1 Measurement approaches
• 11.3.2 Uncertainties
• 11.4 Characterization of a microwave-band spatial-channel "hybrid" test chamber with a synthetic-aperture system
• 11.4.1 The environment: chamber design and configuration
• 11.4.2 Measurement setup
• 11.4.3 Measured results
• 11.4.4 Measurement uncertainty
• 11.4.5 Hybrid-chamber test environment
• 11.5 Millimeter-wave synthetic-aperture system in a highly reflective industrial environment
• 11.5.1 The environment: industrial utility plant
• 11.5.2 Measurement setup
• 11.5.3 Analysis approaches
• 11.5.4 Measured results
• 11.5.5 Summary
• References

Inspec keywords: testing; radio networks; multipath channels

Other keywords: OTA; spatially diverse multipath environments; spatial characteristics; synthetic-aperture techniques; post-processing; temporal characteristic reconstruction; spatial volume; over-the-air testing; DUT; wireless device under test; over-the-air performance assessment; wireless communications; synthetic-aperture-system measurements; reference measurements

Subjects: Radio links and equipment