• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 31 subscribers
  • Views 457 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

AWR1642BOOST: Radiation performance and dielectric material selection?

James Austrial
Expert 4030 points
Part Number: AWR1642BOOST

Hi

Customer follows the AWR1642BOOST design: Use Rogers 4835 (er~3.48, thickness 4 mils, layer 2 is ground plane) at 77 GHz, the efficiency of radiation will degrade -15.72 dB as the blue line below

If customer change its material to be er=94.87, it did not exist radiation loss as the green line below.

Do you have any comment about the result?

Does this mean the design of AWR1642BOOST is not good enough or there're something wrong in customer's test?

  • 0
    TI__Guru 58035 points
    Hello James,
    In general antenna efficiency improves with lower dielectric material. Could you clarify what is the "power density" referring to here? What is the exact simulation done ?

    Regards,
    Vivek
  • 0 in reply to Vivek Dham
    Prodigy 10 points
    Dear Vivek,
    I just used a equation to evaluate the radiation of antenna. Baically , using a point source and get its far field radiation.
    The radiation is varied by the substarte thickness, dielectric constant , and its phycical structure (w/ or w/o backed grounding plane).

    From TI reference design for 77 GHz radar, the distance between array antenna (layer 1) and ground plane (layer 2) just be 4 mils (0.1 mm) only. The recommended substrate is using RO4835 (its dielectric constant is about 3.48). An current type radiator beyond the grounding plane will damage its radiation capability. I just doubted current antenna reference design from TI is not good enough. We hardly put the antenna closed to any metallic plane at a real case.

    The figure is shown the comparisons of using low dielectric substrate and very high dielectric substrate at the same substrate thickness and it caused different eadiation efficiency.

    Thanks!
    Felix
  • 0 in reply to Felix Huang73
    TI__Guru 58035 points
    Hello Felix,
    On a PCB antenna design the antenna needs to be referenced to a ground plan. From what I know lower dielectric constant is better for PCB antennas, not the other way. You could read up some material on PCB antenna , some reference material can be found here:
    www.microwavejournal.com/.../18190-picking-pcb-material-for-a-patch-antenna
    www.ti.com/.../swra117d.pdf


    Regards,
    Vivek