Patch Array
Understanding Patch Arrays
Patch arrays have become the most important antenna technology for modern wireless systems. Their planar form factor, ease of fabrication on PCB, and compatibility with IC-based beamforming make them ideal for mass-produced electronically scanned arrays.
Patch Array Configurations
- Corporate-fed: Binary power divider tree feeds each element. Wideband but higher loss.
- Series-fed: Elements tapped along a microstrip line. Compact, narrowband, beam squints with frequency.
- Sub-array: Groups of patches fed by a corporate network, with phase shifters between sub-arrays for beam steering.
Patch Array Applications
- 5G mmWave: 28/39 GHz arrays with 64-256 elements for base stations and 4-8 elements for handsets.
- LEO satellite: Flat-panel user terminals with 512-2048 elements for Starlink, OneWeb.
- Automotive radar: 77 GHz arrays with 12-48 elements for ADAS and autonomous driving.
Frequently Asked Questions
What is a patch array?
A patch array combines multiple microstrip patch elements on a PCB to achieve higher gain, beam steering, and pattern control. Patch arrays are the dominant antenna for 5G mmWave, satellite terminals, automotive radar, and many military applications.
How much gain does a patch array have?
Gain = element gain + 10log(N). A single patch has ~7 dBi. A 16-element array: 7 + 12 = 19 dBi. A 64-element array: 7 + 18 = 25 dBi. A 256-element array: 7 + 24 = 31 dBi. Actual gain is slightly less due to scan loss and feed network loss.
Can patch arrays steer electronically?
Yes. With phase shifters at each element (or sub-array), the beam can be electronically steered. This is the basis of modern flat-panel phased arrays. Typical scan range is +/- 60 degrees from broadside.