Re: Making a Q-meter / References etc
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That's useful. Can I suggest a few improvements? 1) The input power of watt is rounded to the nearest integer - it would be useful if it allowed a few decimal places, as entering powers in nW or similar is not unusual. But if I enter 1.4 W, it gets rounded to 1 in the input display, but the outputs are more sensible. 2) You might consider whether it's worthwhile adding dbW. I know it's not used a lot, but our amateur licenses in the UK are specified in dBW now, not watt. 3) You say dBm is referenced to 1 mW, and dBuV is referenced to 1 uV, but for dBmV, you spell out the millivolt, rather than just put 1 mV. 4) You mention dBu, but don't allow anyone to perform any calculations with it. 5) There's a spelling error - impemdence 6) According to the BIPM, the body that defines the SI standards, virtually all SI units and derived units should be spelled in lower case, and without the s - so watt, ampere, volt, not Watts, Volts, Amps etc. I think the only exception to this is degrees Celsius. (I have attached a copy of the SI document). 7) If on the voltage gain section, I put an input of 1 V, and an output of -2 V, the calculator shows an error. * It's easy to configure an op-amp to have a negative gain (inverting amplifier). * A VNA will often measure a reflected voltage that is 180 degrees out of phase with respect to the input. I personally would take the absolute magnitudes of the voltages and use that to calculate the gain, so as to not show an error when the input and output are of a different sign. 8) According to the BIPM, there should be a space between a number and a unit - ie 2 uV not 2uV. 9) You are inconsistent in your use of P1 and P 1, and likewise V2 and V 2. Personally I would remove the spaces, as spaces imply multiplication. Or perhaps consider the use of subscripts. 10) I think the last part is potentially wrong, if the DUT does not accept all the input power. If the device reflects a lot of power on the left hand side, then the input power can be high, the output power low, but the dissipation is also low. When calculating antenna gains, the values are in terms of power accepted by the antenna, not the input power to the antenna. I can think of two things you could usefully add. 1) The ability to calculate output voltages given an input voltage and a gain. 2) Noise temperature to noise figure and noise factor conversions. It looks like a useful calculator, but there are some random suggestions of mine. Dave Dr David Kirkby Ph.D Email: drkirkby@... Web: Kirkby Microwave Ltd (Tel 01621-680100 / +44 1621-680100) Stokes Hall Lodge, Burnham Rd, Chelmsford, Essex, CM3 6DT. On Mon, 29 Aug 2022 at 20:45, Rodger Bean <rodgerbean@...> wrote:
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Dr. David Kirkby, Kirkby Microwave Ltd
