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  • Users: groundhog1
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  1. groundhog1

    Measured a CP antenna and linear good, CP pattern bad.

    I built up a plain rectangular patch antenna with the probe feed on the diagonal to set up circular polarization. Using my network analyzer, and putting itentical antennas on both ports, everything looks fine to me. I can rotate the antenna and at center freq, the insertion loss between the...
  2. groundhog1

    modeling question on basic CP square patch..

    Hello, I am trying to make a standard almost square patch with probe feed, where the feed is kind of along the diagonal of the patch. To simulate/measure axial ratio, I put in a very small pickup dipole element with impedance of 377 some distance from the antenna under test (AUT) face. Then I...
  3. groundhog1

    Patch ant with both Left and Right Circular polarization?

    Is it possible to do a patch antenna with both Left and Right hand circular polarization? Say you had a square, probe fed circular patch antenna. You put the probe feed somewhere on the diagonal to match and create the circular polarization. What if you put another probe on the other diagonal...
  4. groundhog1

    My first VBA Excel program doesn't port to new computer..

    I developed my first Excel program and it works great on the computer on my desk. Last night I tried to run it on the manufacturing computer and it has a compile error. I can't totally remember the error message and I am not at work right now, but I will update this post shortly. It make me...
  5. groundhog1

    Thankyou...

    I want to thank you all (joerd, johnwm.. ) for your help and suggestions. My little program has chugged through it's first real production unit and all I saw was pass, pass, pass... Still some improvements to be made, but it is pretty much a useful tool now. Thanks. I have thrown in some...
  6. groundhog1

    VBA variables that exist over all modules? And file saving.

    1.) Is there a way to create a variable that lasts forever and is usable over all modules? My code is in several modules and I want several things to be constant, like the serial number of my unit under test and maybe the partnumber. Stuff like that. Right now I am just reading it off of the...
  7. groundhog1

    What does this mean..?

    I am in excel learning to use VBA so that I can simply try to get a marker value from an Agilent network analyser. I have one of their .xls examples and it does all kinds of things to the analyser, but I can't seem to figure out how to modify the darn thing! THe analyser is on the network...
  8. groundhog1

    How much power can microstrip handle?

    Somebody just asked me if we could put 100-200 watts CW through some pc board mounted relays and filters.... Would co-planar be better? Maybe stripline but that would be a more complicated pc board. Then they asked if we could use PIN diode switches. I think I have seen some PIN diode...
  9. groundhog1

    HDTV serialisers and deserialisers, NRZI .....

    I am learning about HDTV communications right now and am stumped on something. I am trying to imagine what the signal spectrum looks like for the uncompressed serial data stream. The High Definition data rate is apparently 1485 Mhz. Then I read that it is NRZI (non-return to zero inverted)...
  10. groundhog1

    My Windows XP HDD..

    (Appologies in advance for my stupidity in this area...) My old laptop broke, so I scavanged the HDD for use as general storage and backup. But I can no longer get to some areas of the HDD because it thinks that I am not authorized. Is there a way to unlock these directories or make it so that...
  11. groundhog1

    Microwave detector diode circuit..... What is the highest

    What is the highest frequency that you can successfully build a detector diode circuit using packaged Surface Mount diodes? I know that for really high frequency operation, you have to transition to bare die. I just don't have a feel for what that frequency is. Thanks, groundhog
  12. groundhog1

    Serial one way link with one Rcvr, multiple transmitters

    I have to start by saying I have mostly an RF circuit design background. I have been asked to do an RF serial one-way data link. I can do that.. Then, of course, the scope gets expanded. Now there are multiple transmitters sending data to the one receiver. The receiver needs to be able to...
  13. groundhog1

    Creating Sleep Mode in Battery Powered Consumer Device

    Hello Everyone, I have a product that will have an LCD display, and is controlled by microprocessor. It is powered by battery (possibly 9 volt). It will draw about 20mA at about 5 volts. I am planning to use a switching DC-DC step down regulator. The problem is, that I don't want to use a hard...
  14. groundhog1

    how do switch mode regulators save you power...?

    If you use a linear regulator at say 10 volts input power and 5 volts out drawing 1 amp, you are burning 10 watts. If you now insert a step down regulator and step the voltage down to 5 volts at your device, doesn't your device still draw 1 amp? And isn't that 1 amp still comming from the...
  15. groundhog1

    Eye diagram overshoot..

    I have a digital data stream displayed as an eye diagram. The data is comming out of my circuit. When displayed on the scope, the overshoot (ringing) is high and a little out of spec. The spec is 10% or less and I am getting about 13%. I have tried a number of things and cannot control...
  16. groundhog1

    Gennum chipset. Anyone used these? HDTV equaliser, cable driver.

    I have to design a circuit that accepts HDTV signals. The circuit must comply with spec SMPTE 292M. It's also been suggested to me to use the Gennum chipset GS1524 which is a cable equaliser and GS1528 which is a cable driver chip. The equaliser chip accepts the signals to the system and is...

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