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  1. photistor

    Designing a 315 MHz antenna on flexible substrate!!!

    You can try to dielectically load the patch. You can add a dielectic over the patch or select a different substrate. Check out Roger Corp.(http://www.rogerscorporation.com/acm/index.htm) You can also dielectrically load the gap of the slot antenna.
  2. photistor

    Balun for a Folded Dipole Antenna?

    You may not need a balun, but you may still need a transformer (or isolator)to get a better match. It depends on the S11 you can live with. You need to determine the RF link requirements and concider how much reflected power the Tx can handle. As a guide a 2:1 VSWR (-9.6 dB return loss) means...
  3. photistor

    uhf reception antenna calculations

    In addition to VE1BLL, you will need to account for the ground effects (mutltipath reflections, terrain obstructions) as well as fade margin. Most manufacturers have a recommended fade margins for their receivers. Look at: http://www.proxim.com/support/all/stratum/technotes/tn2001-08-13a.html...
  4. photistor

    Beam-Forming Network

    I agree with BrianR, more details are needed. I used to work with EMS. They manufacture BFN's. http://www.emsstg.com/space_sol/beam_forming_networks.asp Also checkout: http://scholar.lib.vt.edu/theses/available/etd-04262000-15330030/unrestricted/ch3.pdf Also, BFN's can be relatively simple or...
  5. photistor

    Can Microwave Office simulate a 1GHz antenna efficiency?

    Depending on the ground plane size check out the Numerical Electromagnetic Code (NEC) programs: http://www.emclab.umr.edu/cemlinks.html http://www.nittany-scientific.com/ (I have used their software 6 years ago, worked well)
  6. photistor

    Microstrip Array

    Also, Ball Areospace & Malibu Research are companies that produce microstrip array antennas: http://www.ball.com/aerospace/ http://www.maliburesearch.com/advancedAnt00.html Other related links: http://ndl.ee.ucr.edu/Myslide.pdf http://www.argospress.com/Resources/antennas/books-antennarra.htm...
  7. photistor

    Frequency Bands and distance

    To add to what VE1BLL stated here are some links for atomspheric attenuation effects, which can alter the free space attenuation. Also rain can effect some frequecies Checkout: http://www.rfcafe.com/references/electrical/atm_absorption.htm http://web.haystack.mit.edu/haystack/files/AtmAtt.pdf...
  8. photistor

    Sources of High temperature dielectric material

    Contact Rogers corp (http://www.rogers-corp.com/). They have some ceramic loaded dielectric materials. Not sure if they have what you need , but they have some "composite" dielectrics. Theu may also have a recommendation. See: http://www.rogers-corp.com/mwu/translations/prod.htm
  9. photistor

    Matching 433 Mhz loop Antenna to RF - IC

    Try: http://www.geocities.com/SunsetStrip/Underground/8585/loop.html http://www.microchip.com/connectivity/rfPICDEM1/files/uwrfa1p6.pdf For books try: "Antennas" by John D. Kraus or for a less mathmatical book try: "Antenna Engineering Handbook" by Jasik Search...
  10. photistor

    wireless design (LAN segment)

    You might try contacting companies like www.adtran.com or www.lgcwireless.com and talk to an applications engineer. You may try researching regular radio repeater articles i.e @ Daniels Electronics (http://www.danielselectronics.com/AnalogApplications.htm). You may try researching some of the...
  11. photistor

    How to load a quarter wavelength monopole

    What is the goal of the reduced efficiency? Are you just trying to limit the range of the system? If so another method of "detunning" or reducing an antenna's overall gain is by using resistive paints or lossy dielectric material(i.e. absorber material). Some of these materilas can...
  12. photistor

    Garage door opener antenna problem.

    If you haven't found the frequency yet you may try searching the FCC number (usally printed near the model and serial number) try the following sites: http://www.fcc.gov/oet/fccid/help.html https://gullfoss2.fcc.gov/prod/oet/cf/eas/reports/GenericSearch.cfm http://www.driverzone.com/fcc_reg.htm
  13. photistor

    measuring RF energy spectrum

    You need the antenna factor for the antenna being used in the measurement. For calibrated antennas visit: http://www.ara-inc.com/bbh.htm http://www.com-power.com/Antennas.htm For info on antenna factor visit: http://www.conformity.com/A03F38.pdf http://www.microindustrie.com/fcc/recaf.htm
  14. photistor

    Loop antenna glued on back of cow-Gain question

    In your original message you asked to predict propagation. If you don't have simulation software you can make a measurement by using watermellons or cantalope to simulate the cow (no joke). If you don't have access to an antenna range you can use a spectrum analyzer to make a path measurement...
  15. photistor

    portable antenna VSWR

    The reflected power that the PA can handle dedpends on the PA design. Most PA's should be desinged to handle a short (or open) at the antenna port. If you were to use an isolator, than the reflected power is "absorbed" into the load in the isloator and the PA is protected. Typically...
  16. photistor

    In microwave antenna far-field patt

    This is an age old issue with antenna engineers. If you ask 7 antenna engineers you get 4 different answers. This can be a very complex issue depending on the platform. If one looks at the equation for gain you'll find it contains a term for the antenna apperature. This aperature term can be...
  17. photistor

    RF Coupling from Antenna

    Review EMI standards and test proceedures. While you may not need to meet MIL-STD's, they may be a good reference. MIL-STD-461 and MIL-STD-462 (There are commerical equivalent standards, I can't remember them right now) Research the tests labled CE (conducted emmisions)& RE (radiated...
  18. photistor

    lpda design

    Check out "Antenna Enginerring Handbook" by Henry Jasik first edtion chapter 18, section 3 (pages 18-10 thru 18-32)for some insight. Note: See page 14-3 in the second edtion version of the same book :"Antenna Enginerring Handbook" by Richard Johnson & Henry Jasik.
  19. photistor

    Radio propagation programs

    I use Comstudy from Radiosoft. I use it for radio coverage for mountain top repeaters/base stations. I do agree with VE1BLL that sometimes it's easer to try it than model it. Some of the software vendors offer free demo versions (with limitations). Comstudy does give you the ability to add...
  20. photistor

    Relationship between 'Channel Decimation Ratio' and fading waveform?

    Did you mean Discrimination ratio? Like in signal to noise ratio? If so, are you asking what happens when your waveform fades or gets weaker and your received signal to noise ratio gets worse (ie 3dB vs 12 dB)?

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