Boeing has developed an active transmit phased array for use in the 14-14.5 GHz fixed satellite service (FSS) spectrum. The array consists of 254 actively controlled elements that radiate variable linear polarization. Measured boresight EIRP is 41 dBW with a beamwidth of 6/spl deg/. Cross-polarization isolation is better than 25 dB at boresight. The antenna can track a satellite from a fixed or moving platform with angular tracking rates better than 30 degrees/sec and at grating lobe-free scan angles greater than 60/spl deg/ from zenith. The antenna, when used with Boeing's commercially available 1515 element Ku-band receive array, provides mobile users a highly capable communications link utilizing geostationary FSS satellites.

Ku-band transmit phased array antenna for use in FSS communication systems

The beam pointing error theory for the phased array antennas (PAA) with true-time-delay (TTD) module is proposed in closed form and is confirmed to be valid. The proposed theory easily gives the optimum subarray size, which is a unit of a TTD module, and maximum delay length of the TTD module in order to attain the desired beam pointing accuracy.

Beam pointing error analysis for phased array antennas with true time delay modules

In recent years, improvements in material types, fabrication processes and manufacturing technologies has allowed the combination of various functions within single, scalable, photolithographically fabricated components. Sometimes referred to as heterogeneous integration or system on a chip, these approaches combine analog devices, digital circuits and antennas to increase system performance and functionality while reducing the size and cost of individual components. These approaches combine RF amplification, power generation, phase and amplitude manipulation, filtering, up and down-conversion and function generation on a common substrate using similar fabrication processes. Such combinations along with the use of planar transmission media, efficient design and analysis tools and miniaturized antennas have resulted in a wide range of low-profile, conformal and integrated system solutions. Single-chip transceiver solutions have already opened up a wide range of applications including wireless communications, remote sensors and low-cost radar. A recent government BAA 05-27, "scalable millimeter-wave architectures for reconfigurable transceivers (SMART)" seeks to continue this type of development at Q-band and above. Thermal, mechanical and electrical packaging considerations determine the level of integration needed to succeed in these on-going efforts. Heterogeneous integration deals with the various trade-offs encountered when combining guided-wave media and antennas. These trade-offs include circuit isolation, Q-factors and radiator field of view, polarization purity and radiation efficiency. The performance of one component versus another is often compromised through either process selection, material types or because of dimensional constraints. These trades come about because of competing, often contradictory, requirements of guided media and radiators. This paper discusses the various packaging constraints encountered during this level of function integration.

Affordable electronically scanned apertures through heterogeneous integration

ETRI has developed an active phased array antenna as an experimental model for use in the mobile satellite-internet services in Ku-band. In this paper, RF transmitter of this phased array antenna system is described, which is one of key components. This RF transmitter consists of TRx duplexer, 1:10 power divider and ten channels including Tx active channel block and antenna. Each subarray is fabricated with 8/spl times/4 microstrip patch. Measured boresight EIRP is 32 dBW with a beamwidth of about 2.5 degrees. This antenna beam can be steered within 3 dB scan loss between /spl plusmn/8 degrees in elevation and /spl plusmn/4 degrees in azimuth. The performance of this transmitter can provide mobile users with a capable communication link utilizing KOREASAT satellite.

An experimental model design of bidirectional communication mobile terminal for Ku-band satellite-internet services

Phased array is a new type of data transmission antenna for remote sensing satellite. The antenna scans its beam to keep the advantage of wide area coverage and high gain to get large EIRP. According to the general requirements of data transmission subsystem employed for earth observing satellite, the relationship of the parameters subject to the phased array data transmission is analyzed. A design of data transmission system suitable for engineering application and a demonstration antenna array is presented in this paper.

Phased Array of Data Transmission System for Earth Observing Satellite

Active phased array antennas with electronically scanned beams offer advantages over high gain parabolic dish antennas used on spacecraft. Benefits include the elimination of deployable structures, no moving parts, and no torque disturbances that moving antennas impart to the spacecraft. The latter results in the conservation of spacecraft power, and the ability to take precision optical data while transmitting data. Such an antenna has been built under a contract from NASA Goddard Space Flight Center for the New Millennium Program EO1 satellite where it will act as the primary high speed scientific data communication link. The antenna operates at X-band, has an integral controller and power conditioner, communicates with the spacecraft over a 1773 optical data bus, and is space qualified for low Earth orbit (705 km altitude). The nominal mission length is one year, and the operational requirement is for one 10 minute transmission a day over Spitsbergen, Norway. Details of the antenna and its performance are given.

K.L. Perko

Papers

Phased array transmit antenna for a satellite