Gerald, One example might be where you need to divide two complex numbers - for example you want to calculate (a+jb)/(c+jd); that requires some tedious maths. However if the complex numbers are expre
Kevin, I assume by "coax baluns" that you mean air-cored baluns. Air-cored baluns have a number of disadvantages: * They are "high-Q" and exhibit a high common-mode impedance over only a relatively n
An EZNEC model of an Inverted-L with 60ft vertical and 77ft horizontal gave me a resonant feedpoint resistance of 32 Ohms at 1.8MHz when the ground loss resistance was 13 Ohms. That same antenna at 3
How is any of this relevant the question about his Inverted-L ? Steve G3TXQ _______________________________________________ _______________________________________________ TowerTalk mailing list Towe
I needed 13 Ohms ground loss to get to his measured resistance of 32 Ohms. But it doesn't matter whether that is right or wrong, nor what the value is on 80m, because compared to the Resistive compon
Over an ionospheric path the polarization is changed randomly and is time-variant. There is no advantage in trying to match (or otherwise) transmit and receive antenna polarizations. Steve G3TXQ ____
I quite often come across explanations of the Gamma Match (or Tee Match) which suggest that a "tap" is being made along the dipole at a point where the "feedpoint" Resistance is higher, and that the
Ken, In the Plot window use "Save Trace as" to save the first trace; then plot the second antenna; then use "Add trace" to recall the saved file. EZNEC will overlay them on the same scale so that the
That's a useful tuner simulation; but **DO** remember it assumes a constant Q for the inductor. Here's how a real roller inductor Q measures at different inductance settings on different bands: http:
That's a useful tuner simulation; but **DO** remember it assumes a constant Q for the inductor. Here's how a real roller inductor Q measures at different inductance settings on different bands: http:
Here's a display which I developed to characterise tuner capability: http://www.karinya.net/g3txq/temp/aat_chart.png Vertical axis is load Reactance in binary steps; horizontal axis is load Resistanc
Paul, I made the measurements myself. The inductor was in the open, sitting on a wooden baseboard. It had a "tapered pitch". The Qs I measured seem to be similar to those measured by Tom W8JI who say
Paul, The results were a bit of an "eye opener" to me - they've certainly made me sceptical about tuner loss calculations based on "constant Q" inductors. I'm pretty confident of their accuracy. They
The most comprehensive calculator I know is Owen's at: http://vk1od.net/calc/tl/tllc.php A good test for a calculator is to look at the loss it predicts for 10ft of 50 Ohm coax at 3.5MHz with a 150+j
Paul, It's not really counter-intuitive when you remember that at HF the vast majority of feedline losses are I*I*R losses and therefore driven by the current that is being carried. If we have a 150
Jim, 27 turns of #12 gauge wire on a 2.2" diameter ceramic former occupying 4" winding length. The final 6 turns had a larger winding pitch. 73, Steve G3TXQ __________________________________________
Paul, The only calculator I fully trust is Owen's (VK1OD). For 10ft or RG213 terminated in 150+j130 at 3.5MHz, his calculator gives a loss of 0.0138dB compared to a matched loss of 0.0351dB. Of cours
Jim, I disagree! If we restrict ourselves to talking about the series-form complex load impedance, the reactive component will *not* affect the current required through the load for a particular powe
Paul, I'm not sure it helps to distinguish between "SWR losses" and "I-squared-R losses" - at HF, all the losses are predominantly "I-squared-R losses". It may help to picture qualitatively the curre
Paul, I checked that page of Owen's earlier for a chart which shows the losses at various distances from a mismatched load; it was the epitomy of "a picture paints a thousand words"! Unfortunately Ow