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  1. searsjames

    Garage door opener antenna problem.

    Would it not just make sense to match the existing length of the hanging wire? I.E. Strip the coax back this far at each end. Dont forget to ground the coax shield to the opener case.
  2. searsjames

    Propagation characteristics of horizontally polarized RF

    My cow antenna my be easiest to configure if it radiates with horizontal polarization. I am interested in the 433 Mhz band as well as 900 Mhz meaning that blocking vertical polarized interference is a Plus. My Questions: Compared with vertical, 1) How well does horizontal propagate over...
  3. searsjames

    Countries allowing 433 MHz telemetry

    Merry Christmas! This relates to the cow questions. What countries allow 433 Mhz telemetry with low duty cycle? I already 433 usage is harmonized in Europe and the US. How about Canada, Austrailia, Brazil, Japan, and Argentina? Much thanks jim
  4. searsjames

    Loop antenna glued on back of cow-Gain question

    OK I am intrigued. It is really unwise to get a cow and a $7000 network analyser within pissing distance. How do you know that a watermellon is a viable substitute? BTW I was on my hands and knees saying moo yesterday. Jim
  5. searsjames

    Loop antenna glued on back of cow-Gain question

    The cow will have an intrinsic impedance of about 50 ohms though I dont know what that means as far as minimizing coverage. I would love to get a diagram of any suggestions. The cow skin does need to breath. W1VT of the ARRL has graciously turned be on to EZNET so now I can analyze simple...
  6. searsjames

    Loop antenna glued on back of cow-Gain question

    64khz FSK modulation, TX=0dbm, there is no coax loss, and -103dbm at the reciever. Hope to get 0 to -5 dbi at the TX antenna, am analysing now...that is the main question I have for this forun.... The propagation models i have checked say things should work. Antenna is the question... What...
  7. searsjames

    Radio propagation programs

    www.ecommwireless.com has several simple point to point calculators for free.
  8. searsjames

    Loop antenna glued on back of cow-Gain question

    >= 1 mile over varied range conditions to 30 foot receiver height, 10-15 mw, .005% Emperical testing is always the best way to be sure. I plan on it. Just getting a head start. Jim
  9. searsjames

    Loop antenna glued on back of cow-Gain question

    Thanks, Collars snag in ranch environments and do not place the transmitter in the physical position we need it. GPS is not used for cost and coin battery life issues. ANOTHER QUESTION. How will the beam pattern change? Will the horizontal donut flare upward or downward? Will nulling of...
  10. searsjames

    Loop antenna glued on back of cow-Gain question

    Gentlemen, I am developing a tracking system operating at 433 MHz that utilizes a loop antenna glued in the horizontal plane to the back side of a cow. The diameter is 1/4 wave and it will be spaced 1/4 inch from the skin. The height above ground will be 4.5 feet. According to...

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