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Electronically Steered Antennas

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Electronically Steered Antennas

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  1. Electronically Steered Antennas Yoel Gat, CEO SatixFy

  2. Outline • Defining the scope • Why electrically steering antenna? • How to electronically steer a beam? • Phased array antennas advantages & disadvantages • True Time Delay (TTD) antenna basics • Loss due to pointing error • Types of electrically Steered antennas • TTD & ESMA technology • Summary: Phased Array Vs. True Time Delay

  3. Defining the scope of the presentation • Real Electronically Steered Antennas (no moving parts) • Solutions that can be demonstrated today (paper products are always better…) • Satellite solutions (not 5G) • Technologies • Analog Phase Shifters • Metamaterial • Digital Beam Forming (True Time Delay) • Challenges • Power • Price (lots of electronics – hence silicon is a necessity) • Calibration (frequency, temperature, scan angles, aging) • End-to-End Full system requirement, including modems on both ends

  4. Why Electronically Steering Antenna? • No moving parts

  5. Why Electronically Steering Antenna? • No moving parts • Low profile

  6. Why Electronically Steering Antenna? • No moving parts • Low profile • Can be conformal

  7. Why Electronically Steering Antenna? • No moving parts • Low profile • Can be conformal • Facilitates multibeam

  8. Why Electronically Steering Antenna? • No moving parts • Low profile • Can be conformal • Facilitates multibeam • Self pointing

  9. Why Electronically Steering Antenna? • No moving parts • Low profile • Can be conformal • Facilitates multibeam • Self pointing • Adaptive directivity

  10. Why Electronically Steering Antenna? • No moving parts • Low profile • Can be conformal • Facilitates multibeam • Self pointing • Adaptive directivity • “All in one“ solution

  11. Why Electronically Steering Antenna? • No moving parts • Low profile • Can be conformal • Facilitates multibeam • Self pointing • Adaptive directivity • “All in one“ solution • And this just ground satellite segment …

  12. How to Electronically Steer a Beam?True Time Delay (TTD) Basics

  13. Parabolic Antenna • A parabolic antenna is physically designed so the wavefront from the boresight direction will be combined coherently (same delay)

  14. Parabolic Antenna (cont.) • Wavefronts from other direction will not be coherently combined (different delays)

  15. Flat Panel Antenna • A flat panel antenna coherently combines the boresightwavefront Antenna patch

  16. Flat Panel Antenna (cont.) • Here too, wavefronts from other directions experience different delays (green arrows) and will not be coherently combined

  17. Delay Lines • If we can add delay lines that compensate the delays that results from the non boresight direction… • Could be implement by phase shifter (approximation of true time delay – at a certain frequency…) • Or by True Time Delay (Digital Beam Forming)

  18. Phased Array vs. True Time Delay (TTD)Signal Bandwidth: Different Scan Angles for Different Frequencies! freq (GHz) Antenna defocused (Beam Squint)

  19. Phased Array AntennasAdvantages & Disadvantages

  20. Phased Array Antennas Main Advantages • Low power • Some implementations are passive • Low cost • One phase shifter per antenna patch • Common RF chain

  21. Phased Array Antennas Main Disadvantages • Low resolution (beam steering jumps by a few degrees) • Typically switching of constant phase shifters

  22. Phased Array Antennas Main Disadvantages • Low resolution (beam steering jumps by a few degrees) • Typically switching of constant phase shifters • Low accuracy • Process variation dependency • Part to part variation • Difficult to calibrate each phase shifter

  23. Phased Array Antennas Main Disadvantages • Low resolution (beam steering jumps by a few degrees) • Typically switching of constant phase shifters • Low accuracy • Process variation dependency • Part to part variation • Difficult to calibrate each phase shifter • Non linear frequency response

  24. Phased Array Antennas Main Disadvantages • Low resolution (beam steering jumps by a few degrees) • Typically switching of constant phase shifters • Low accuracy • Process variation dependency • Part to part variation • Difficult to calibrate each phase shifter • Non linear frequency response • Silicon size is typically inversely proportional to the frequency • Lower frequency phase shifters are big

  25. Phased Array Antennas Main Disadvantages • Low resolution (beam steering jumps by a few degrees) • Typically switching of constant phase shifters • Low accuracy • Process variation dependency • Part to part variation • Difficult to calibrate each phase shifter • Non linear frequency response • Silicon size is typically inversely proportional to the frequency • Lower frequency phase shifters are big • Difficult to build large antennas • Constant delay RF routing • Long routing with several RF splitting / additions • Not true time delay (explained later)

  26. Phased Array Antennas Main Disadvantages • Difficult to build multibeam antennas • Requires RF summation and splitting • Number of beams in a RF chip needs to be known in advance • Low resolution (beam steering jumps by a few degrees) • Typically switching of constant phase shifters • Low accuracy • Process variation dependency • Part to part variation • Difficult to calibrate each phase shifter • Non linear frequency response • Silicon size is typically inversely proportional to the frequency • Lower frequency phase shifters are big • Difficult to build large antennas • Constant delay RF routing • Long routing with several RF splitting / additions • Not true time delay (explained later)

  27. Phased Array Antennas Main Disadvantages • Difficult to build multibeam antennas • Requires RF summation and splitting • Number of beams in a RF chip needs to be known in advance • Can not support large bandwidth • Not true time delay (explained later) • Low resolution (beam steering jumps by a few degrees) • Typically switching of constant phase shifters • Low accuracy • Process variation dependency • Part to part variation • Difficult to calibrate each phase shifter • Non linear frequency response • Silicon size is typically inversely proportional to the frequency • Lower frequency phase shifters are big • Difficult to build large antennas • Constant delay RF routing • Long routing with several RF splitting / additions • Not true time delay (explained later)

  28. Phased Array Antennas Main Disadvantages • Difficult to build multibeam antennas • Requires RF summation and splitting • Number of beams in a RF chip needs to be known in advance • Can not support large bandwidth • Not true time delay (explained later) • Difficult to support large scanning angles • Not true time delay (explained later) • Low resolution (beam steering jumps by a few degrees) • Typically switching of constant phase shifters • Low accuracy • Process variation dependency • Part to part variation • Difficult to calibrate each phase shifter • Non linear frequency response • Silicon size is typically inversely proportional to the frequency • Lower frequency phase shifters are big • Difficult to build large antennas • Constant delay RF routing • Long routing with several RF splitting / additions • Not true time delay (explained later)

  29. Maximum Bandwidth for 3dB Loss Vs. Scan Angle Array Size

  30. Phased Array Frequency Response 16x16 elements, square, Spacing d = /2, Steering 45o, 45o Center frequency = 30GHz, Bandwidth = 2 GHz Perfect Equalizer: SNR Loss = 0.24 dB Beam Edge Loss = 2.46 dB

  31. Phased Array Frequency Response 64 elements, linear, Spacing d = /2, Steering 45ooff-boresight Center frequency = 30GHz, Bandwidth = 2 GHz Boresight Perfect Equalizer: SNR Loss = 2.33 dB Beam Edge Loss = 9.81 dB

  32. Types of Electrically Steered Antennas

  33. ESMA TechnologySize vs. Bandwidth • Inherent benefits of DIGITAL • Unlimited number of antenna elements, allowing large panels at high BW True Time Delay (TTD) Phased Array technology bandwidth limit

  34. Calibration • Need to calibrate every element in phase and amplitude to get the gain of the array • Among other topics • Frequency • Temperature • Delay • Scanning angles • VCO • Aging • Most sophisticated and difficult part of the process. Relatively easy to operate an array at boresite, but not easy at all to do over all parameters • Huge advantage of DIGITAL Beam Forming

  35. End to End System • Its not just about the antenna • In an Aero antenna there are 5 parts • Antenna • BUC/LNB • ACUModem • Power Supply • ESMA supports all in a single antenna board: Power in – Ethernet out • Having integral modem is significant advantage • ACU (very important in multi-beam) • Low Power modes: No data – no power • Integrated with Hub side

  36. Summary I: Phased Array Antenna Vs. TTD • Many people sell chips for analog phase shifters • Easy to build single beam antennas with limited performance and limited scan angles • Market is expected to be dominated by low cost Chinese products in 5 years • It is when you try to calibrate when you start encountering difficulties • Phased array antennas have many limitations: • Beam Squint • Array size • Bandwidth • Scan angle • TTD solves all this issues: Requires dedicated silicon chips but provide superior performance

  37. Summary II: Best Payload Technology • 16 X 500MHz beams • Full Duplex Tx, Rx arrays with X,000 elements, with tapering • Link with 6db SNR for 10 db G/T User Terminal • Full digital beam forming • SDR Modem with Beam Hopping and On-Board-Processing • Less than 1 KW • All enabled on True Time Delay Beam-Forming

  38. Summary IIIElectronic Vs Mechanical Solutions - Comparison

  39. Thank You SatixFy