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measuring speed with x band motion detector — Parallax Forums

measuring speed with x band motion detector

Greg SumnerGreg Sumner Posts: 4
edited 2011-11-28 11:10 in Accessories
Hi, i've just bought the x-band motion detector and am waiting for it to arrive. I was hoping to fit some form of directional antenna to it and measure the velocity of people or similar. I understand how to interface it with a microcontroller and measure the doppler shift but was wondering if anyone knew what type of antenna/horn i should fit for an increased range? Any help would be appreciated, thanks.

Comments

  • steve_bsteve_b Posts: 1,563
    edited 2009-12-02 17:16
    a fun test would be to use a pringle's can?!

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    <FONT>Steve



    What's the best thing to do in a lightning storm? "take a one iron out the bag and hold it straight up above your head, even God cant hit a one iron!"
    Lee Travino after the second time being hit by lightning!
  • Greg SumnerGreg Sumner Posts: 4
    edited 2009-12-02 22:26
    ah, good suggestion! that will be high on my list of solutions to try. The only problem I could foresee would be the rx being swamped by the tx from the reflections inside the can. also, i've read that wr-90 waveguide is used for 10ghz so I was thinking of putting a rectangular piece of that over the pcb antenna. don't suppose anyone would know if I will achieve anything by doing that?
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2009-12-02 23:10
    I worked on I-J band travelling-wave tubes for several years and I say without reservation that you cannot achieve any desirable result by attaching some rectangular piece of metal or somesuch as you propose.· VSWR, mismatch, return loss, insertion loss --·forget about it.· Just leave it alone.
  • Greg SumnerGreg Sumner Posts: 4
    edited 2009-12-02 23:22
    Thanks, ive read a little bit about microwaves and was beginning to suspect that wouldn't achieve anything. if i were to remove the pcb antenna would you have a suggestion for another type of antenna which would work? or should I just stop trying right now?
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2009-12-03 02:14
    http://www.ramseyelectronics.com/cgi-bin/commerce.exe?preadd=action&key=SG7
    ·
  • Greg SumnerGreg Sumner Posts: 4
    edited 2009-12-03 02:27
    I'll try that once ive given up on the sensor ive already ordered, thanks for your help.
  • artie123artie123 Posts: 5
    edited 2011-11-28 11:10
    I'm a ham radio operator with some microwave experience, although I cannot do programming......I envy those that can do programming, but something in my brain prevents me from learning it.

    The range can be increased with a simple horn antenna. But the module has patch antennas, so the geometry prevents one from doing a proper and technically correct antenna. You also create other technical issues by adding any sort of 'antenna'.

    You can't feed it with a waveguide as the patch antennas are physically larger than 10 GHz waveguide. You might be able to build twin dipoles (one for rx and the other for receive), but you will need to provide some isolation between them. Having dipole antennas makes feeding any sort of dish or horn antenna much more technically correct. But there are many other problems that might surface with the addition of mods.
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