Extracted Millimeter Wave Dielectric Variations Impact on Automotive Radar Type Approvals
Substrate dielectric drift at 77 GHz alters antenna phase and EIRP, requiring strict raw material controls to prevent regulatory non-compliance and re-filings.
Spatial Side Lobe Suppression
Meaning
Directional radiation characteristics of phased arrays must concentrate electromagnetic energy in a specific direction while minimizing emissions in unwanted angles. The technique of spatial side lobe suppression reduces the amplitude of the secondary beams that form adjacent to the main lobe of the antenna pattern. These secondary lobes are problematic because they can cause interference to other wireless systems or receive unwanted noise from outside the target area.
By applying amplitude tapering or phase adjustments across the antenna elements, designers can control the overall shape of the radiation pattern.
Pattern Modification
Modifying the distribution of signal power across the array elements directly alters the radiating profile. This pattern modification is achieved by applying mathematical windowing functions to the excitation weights of each transceiver channel. Forcing the outer elements to transmit less power than the central elements significantly reduces the height of the secondary lobes.
However, this adjustment also increases the width of the main beam, requiring a balance between pointing precision and suppression levels.
Interference Reduction
Reducing secondary radiation is critical in dense communication networks. The interference reduction achieved by this technique improves the signal-to-noise ratio. It prevents the device from broadcasting signal power in unwanted directions.
Hardware Realization
Realizing these design goals requires precise control over the hardware components. The hardware realization involves using programmable phase shifters and attenuators within the RF front-end module. These components must be calibrated to ensure that amplitude and phase variations are kept within tight limits.
Any hardware imbalance in the feed network can degrade the suppression performance, making high-precision test verification essential.