Phased Array System for Wireless LAN

The wireless LAN (WLAN) is gaining more and more consideration in current communication systems. As the frequency increases, the system can be small and a high data rate and a large bandwidth are possible for audio and video communication. To realize this reliable peer-to-peer approach, which allows direct communication between terminals without requiring a central base station, a phased array is used in the system front end. Phased arrays of printed antennas are of considerable current interest, particularly in the context of millimeter-wave monolithic arrays, where active devices for phase shifters and amplifiers are integrated on the same or similar substrate as the radiating elements. Such systems potentially offer high reliability and low cost, low profile as well as high performance. In the WLAN application, another important advantage of phased arrays is that with its adaptive beam forming, users can find each other in a more efficient way while less power is consumed.

Phased Arrays for NetworksI
The GaAs MMIC PALNA chip using Rockwell PHEMT process has following specification and measured performance: Die Size: 1.3 mm x 1.9 mm, Operating Frequency: 24 GHz LNA Gain:15dB, Output Match: -8dB, Noise Figure: 4dB @24GHz PA Gain: 20dB, Output Power: 60mW, Power-added efficiency: 25 % , Output Match: -4dB @24 GHz This amplifier is the first reported PALNA design at this high frequency. The 8x5 patch array is combined using Wilkinson power combiners, and has successfully achieved the following performance: Board Size: 5cm x 5cm, Impedance Bandwidth: 2.26% (23.63-24.17GHz) Gain: 19.68dBi @ 24GHz, SL (Sidelobe Level) < 10dB.
The phased array system is designed for 24GHz. It includes a patch array, a GaAs MMIC amplifier and silicon front-end mixer and oscillator. The 8x5 element patch array is a resonant series array designed on RT/Duroid 5880 material from Rogers Corp. The measured gain is 20dB at 24GHz, with a 30-degree beamwidth in the E-plane and 20-degree beamwidth in the H-plane. The beam can be scanned 45 degrees in the H-plane in both directions.. The PALNA (Power Amplifier and Low Noise Amplifier) chip was fabricated at the Rockwell Science Center

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updated March 1, 2001