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  1. Higgler

    Faraday Cage Shielding by Frequency

    higher frequencies get into a box easier due to "waveguide cutoff phenomenon". Box screws make it a High Pass Filter. Always add absorber into a metal box that you don't want to seal from RF. Salt water in a bag is the cheapest and best for a quick try just to see. Good box designs have one...
  2. Higgler

    Modification of 3x sector antennas

    those are pretty high gains, 10 dB are 60x60 degree beamwiths. Show a pic or data of the antennas. In general higher gain antennas can be placed next to each other without problem, low gain ones are really touchy. For a system to work, you need to have system requirements. List them with antenna...
  3. Higgler

    DC blocking design from 900MHz to 2.4GHz?

    novel DC block printed on same layer, 1/4 wave length, dual lines http://amsacta.unibo.it/364/1/Eug_6_2.pdf
  4. Higgler

    DC blocking design from 900MHz to 2.4GHz?

    It was a bit higher than yours 5.8 ghz top end. Overlapped lines are capacitors.
  5. Higgler

    DC blocking design from 900MHz to 2.4GHz?

    In an old quad coupler design, we needed a dc block, we used just two overlapping printed transmission lines, insulated by dielectric gives a dc block, no capacitors needed. Once you print the layout and prove it, saves on components.
  6. Higgler

    Adhesive to handle extreme cold, but one I can melt at about 75C

    Objective is to prevent movement. In a former company's warning letter, all blindmate connections should be staked with epoxy. I'm under the impression that epoxy is very difficult to remove from a tube. I wish to use heat to soften the material so that I can pull the blindmate cable out...
  7. Higgler

    Yagi internet antenna improvements

    I was instructed by my antenna professor in 1979 to propagate the name Yagi-Uda, or better Uda-Yagi. Uda was a Grad Student who did most of the work developing and perfecting this antenna. Yagi, his supervisor took most of the credit. Per Dr. AD Wunsch.
  8. Higgler

    Adhesive to handle extreme cold, but one I can melt at about 75C

    I have a RF cable placed inside a tube which blind mates with the mating connector located on a back wall, and It's difficult to secure the cable, I can only push it in, no mechanical connection other than tynes and spring blindmate contact. I don't want the cable to move during travel. I'm...
  9. Higgler

    Yagi internet antenna improvements

    First try moving your antenna up and down by just a few inches, or a few feet. If you can borrow a Spectrum Analyzer and look at received power that will help. RF Bounce off the ground or buildings can really lower received power, or raise it too from multi-path.
  10. Higgler

    Yagi internet antenna improvements

    Arraying 2 or 4 is a better way to increase gain, if they are build identically.
  11. Higgler

    Microwave transformer electromagnet questions..

    This one's real heavy duty. http://www.amazon.com/Heavy-Duty-Forklift-Magnet-Magnetic/dp/B00A29M1TM/ref=pd_sim_sbs_indust_3
  12. Higgler

    converting motors to voltages used outside the US

    Amazon product (link below), $400, 50 hz input (single or three phase), output 60 hz(3 phase only)(4 kilowatts, 5 hp). Description 5hp 4kw 220-250v Variable Frequency Drive Inverter VFD with Extremely Strong Anti-jamming Capability...
  13. Higgler

    Question about repeating tv antennas.

    I had OTA reception for a while. Frustrating that the signal will disappear at any time (due to wind mostly), with no hint when it will come back. Only use this if you are reasonably close to TV transmitters (i.e. living in a city). I suggest you order cable internet, buy a Radio Shack 3 dB...
  14. Higgler

    Homemade iPhone 5 antenna

    comcokid's answer is reasonable and lightweight. You could try a simple reflector design and get more gain depending on reflector size. How you'd make it for hiking convenience is the challenging part (rolled up wire/metal mesh screen door? use reflector curved in the horizontal plane only...
  15. Higgler

    microwave sensor independant of polarization

    Use a dual polarized (circular?) waveguide horn. If your test equipment can measure phase, or compare the phase of the two polarizations) then the polarization of the incoming energy can be determined exactly mathematically. If no phase information, it would help to have two dual polarized horns...
  16. Higgler

    Patch antenna ground plane effect on radiation pattern

    What size ground plane are you mounting it on and how close to the edge. In general the companies that sell GPS antennas suggest a ground plane minimum size. If the ground plane is too small, the antenna shifts frequency, and that'll kill your sensitivity much more than the patterns going askew...
  17. Higgler

    Checking holes perpendicularity

    My company did a recent project for a large aircraft manufacturer to measure holes in sheetmetal using photographic techniques. It was to measure the hole location relative to an edge. I've spoken to our workers about measuring dings/dents and we came up with a plan using dual digital cameras...
  18. Higgler

    How to make small (< 1m) HF antenna?

    The most difficult antenna to test accurately is the low frequency antenna. Expect your environment (and the RF inadvertent bounces off that environment) to swamp out results. i.e. take some measurements, move test locations, totally different measurements. Potential waste of time.
  19. Higgler

    Antenna matching at 2 MHz

    You are essentially operating at AM Radio frequency-ish (1.6 Mhz is high end of AM). If your antenna is a simple loop, with no ferrite core, substitute an AM radio antenna for comparison to your current setup. Might be better.
  20. Higgler

    Small Antenna Close to Ground

    Rf signal bouncing (actually reradiating) off the ground will cancel or help your direct signal. It's a significant problem that has led to many inventions in signal diversity (both antenna placement, switching (home wifi- 3 antennas on the box) and signal modification (OFDM) OFDM=...

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