MOBILE 4 element phased array

Discussion in 'Mobile Radio' started by W4EAE, Jun 11, 2019.

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  1. W4EAE

    W4EAE Subscriber QRZ Page

    I recently noticed some new antenna installations on the cars belonging to my local constabulary. I struck up a conversation with one police officer at a gas station; and while he knew nothing about the technical aspects of his antennae, he let me measure the setup. It consists of 4 full-wave 800MHz vertical elements, spaced a half-wave apart from each other (nearest) in a square.

    I am curious if anyone was ever experimented with something like this for 2m or 70cm (obviously not full-wave). It has gotten me curious.
     
  2. WB5WPA

    WB5WPA Ham Member QRZ Page

    LoJack. 173 MHz.

    The equivalent for hams is Doppler DF for 2 m or 70 cm.

    https://www.lojack.com/for-law-enforcement/
     
  3. K7JEM

    K7JEM Ham Member QRZ Page

    It does sound like the layout for Lojack, but if his measurements are right, the spacing is wrong. Also, an 800 MHz antenna would need to have a coil in it, if it is a straight piece of radiator, then it is not for 800MHz. An 800MHz "full wave" would be around 14", which would be pretty close to a QW at 173MHz, but not quite.
     
  4. K3UJ

    K3UJ Ham Member QRZ Page

    Adcock array. Yes, that's for LoJack.
    Hams have used them for 2M Fox Hunting.
    Want one? http://www.kn2c.us/
     

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