Ka Band Phased Array Development Platform

Abstract— The growth within the satellite communication market continues to expand rapidly with advances in technology.  However, the barrier to entry is driven predominately by cost and risk.  The cost for research and development, thousands of manhours required from a multidisciplinary team, and the development cost to build and validate a proof of concept can be overwhelming.  Especially for those who would like to explore the application space for the first time the cost and the risk may be prohibitive.  To help ease the barrier to entry into the phased array technology space for satellite communication, the Aerospace and Defense organization within Analog Devices has developed a Ka band evaluation platform.  Coupled with the development platform is a collaboration with Keysight Technologies on array calibration.  Phased array antenna calibration has typically been time consuming and expensive.  A compact antenna range coupled with commercial test equipment provides an economical and fast solution for calibrating these antennas 

Keywords—Ka Band, phased arrays, beamforming, Electronically Steerable Array (ESA), satellite communications,

I. INTRODUCTION

As a result of the proliferation of LEO satellite constellations, phased array antennas have gained interest due to their many advantages over parabolic reflector antennas.  The main drivers that make it attractive are more flexibility and higher reliability, as well as the ability to maintain satellite communications links with an orbiting LEO satellite traveling at approximately 27,000 kilometers per hour.  Conventional parabolic reflectors rely on servo motors and actuators to move or steer the beam to the desired position.  This in turn results in a large and bulky system that is slow to maneuver and less reliable as it is prone to single point failures.   Phased array antennas utilize electronic means to rotate or steer the beam which is void of any mechanical mechanisms thus improving overall reliability.  A phased array antenna consists of an array of antenna elements and by adjusting the phase of each transmitting element the beam is steerable in an efficient and reliable manner. 

A phased array system offers improved performance advantages such as enabling multiple beams, agile beam steering, and beam pattern optimization.  Theoretically, phased array antennas can generate as many beams as desired by the beamforming network.  However, the practical limitations lie within the actual capacity of the hardware. For low beam count systems analog beam forming offers the most cost-effective solution with respect to power consumption and engineering complexity.  As the beam count continues to increase, hybrid beamforming serves as the middle ground and then digital beamforming offers the highest number of beams.

Concerning agile beam steering, for a phased array antenna the beam direction is electronically steered, and this is achievable at a much faster rate, in the order of milliseconds, as compared to parabolic antennas.  A key advantage of electronic beam steering is that the beam patterns are reconfigurable in real time.  This offers almost instantaneous system performance improvements and optimization.  For example, high sidelobe levels off the main beam may cause miss tracking and/or interference with neighboring transmitters or receivers.  By applying amplitude tapering and phase control of the antenna elements, the phased array antennas can control the side lobe levels and nulls can be strategically positioned to attenuate interfering signals.  

Phased array antennas offer almost instantaneous beam pattern reconfiguration and graceful degradation with component failure and aging as required for the application space.  These advantages offer both hardware and software designers the opportunity to explore novel analytical algorithms and engineering techniques to improve on the overall system design as it applies to communication, RADAR, and/or satellite systems.  

Analog Devices, Inc. has all the necessary building blocks for a complete antenna to bits phased array system design.  The available portfolio of products includes RF/millimeter wave components, highly integrated beamforming ICs, data converters, and power management.  To help ease the barrier to entry into the phased array technology space, the Aerospace and Defense organization within Analog Devices has developed a Ka band evaluation platform.  The development platform consists of an independent transmit system targeting 27 to 31 GHz and a separate receive system for 17.5 to 20.5 GHz.