Resonance or Lowest SWR (

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Chris, KB1NLW, is wondering if the antenna will have the highest efficiency if tuned for the resonance and if low SWR can be achieved through a tuner. Watch to learn more.
#antennas #SWR #Resonance
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Опубликовано:

2 окт 2024

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Комментарии : 21

@joeschoebel1458 Год назад

Glad to see someone show that resonance and low SWR are not the same thing! We have gotten kind of lazy now with all our antennas designed for a 50 ohm feedpoint impedance and 50 ohm coax. Open an ARRL Antenna Handbook from pre-1960 and you'll find LOTS of great antennas that are fed with open wire feedline (450-600 ohm or even more!) End fed antennas that don't use a balun to match impedance, but a specific length of feedline as a matching network! Once this concept of resonance is understood there is a whole new world of antennas to make!

@davidc5027 Год назад

It is the audience, including myself, Dave is teaching. More advanced antenna design is always freely available to those who seek it.

@DaDitDa Год назад

Perhaps this may add some clarity: To a great extent, power reflected from a mismatched load is not dissipated in its source, it is re-reflected from the source. Some reflected power is dissipated in the transmission line, and some is eventually dissipated in the load. An L/C network used to achieve a conjugate match (i.e., antenna tuner) at the load or at the source will dissipated some power, depending on the Q of the components utilized. If the network is between the transmission line terminus and the load, it appears as the load to the transmission line. If the network is between the source and transmission line, it appears as the load to the source, and as the source to the transmission line. With the network at the source, any mismatched load and associated line losses remain; but maximum power will be supplied by the source due to the matched load condition achieved by the network at the source. Ken WA8FCI

@subramanianr7206 Год назад

Yes, the best answer to the question. Dave would look into this I believe 👍 De VU2RZA

@snatr 21 день назад

I was just dealing with something along these lines while building a little j-pole antenna for my GMRS radio. The real issue I was concerned with is that I was using 75 ohm cable as the feed line. So I ended up moving the feed point of the antenna around and trimming for the frequency at the same time using a vna to get the lowest swr I could. But I was still ending up a little on the high side of the ohms according to the Smith chart. The whole thing about 50 ohms is confusing to me in the first place though.

@sleeve8651 Месяц назад

Seems an important item missed in your explanation, is bringing the resistance to 50 Ohm's, the typical transmitter of today, would not be nearly as taxed, leading to cooler operation, longer life, etc. ! Too, going out on a limb, but going off what you are calling resonance, one side or the other, as long as the SWR isn't prohibitive, won't make you any less apt of making contacts ! And likely talking differences so small that would likely not be noticed at the receiving end ! Obviously, if one wants an SWR figure over a larger swath of frequencies, then you use a larger diameter conductor for your antenna ! In other words, don't sweat the small stuff, trying to eek out every last morsel you can squeeze, but instead use that time to make contacts ! Just my Two cents, or a little more figuring inflation ! 👍😉

@KD2ZTA Год назад

Maybe this explains the tuning of a magnetic loop antenna?? You first tune for peak noise and then tune for lowest SWR. When looking at a waterfall display with an expanded span, the peak noise often becomes off-center of the frequency you are on when you tune for lowest SWR.... If this is true, is tuning for lowest SWR really that important if it is not excessively high?

@DonzLockz Год назад

A DX Commander is the answer. Dave has some video's on how to assemble it.

@davidc5027 Год назад

Well of course! There is a DX before the word Commander, so you know it is an antenna specifically designed for distant contacts ;)

@subramanianr7206 Год назад

Dave, it is obvious that you became nervous as you have not done just to the question...hi.. De VU2RZA

@KX4UL Год назад

Good video...73!

@Frankh77 Год назад

Didn't we see this one already? Or was it part of another topic in the past?

@WILLIAMPERRELLI Год назад

Dave hi Question. I hv an end fed 6-80(142 feet)Running an icom 7300 and I would like to get on a small bit of 160. Even in emergency mode, I cannot tune it. EM does tune the 3.92-4.00 portion of 80, which my internal tuner will not. Anyhow, would an external tuner like an Mfj-939 be able to hit a bit of 160? Thanks William

@newYorkStories Год назад

An SWR of 1:1.5 seems like unachievable for me.. oh well

@Frankh77 Год назад

I trim or tune antenna for the bands using, to get it close, and let the antenna tuner do its thing to make the radio happy.

@ericdee6802 Год назад

I never understood the use of an antenna tuner, why not tune the antenna in the normal fashion by properly cutting the antenna to length per a mathematical equasion for the frequency???

@patdbean Год назад

Because you would need a different antenna for every band you wanted to transmit on. And wide bands like 10M would need more than one antenna. And yes I know you can use traps, but they themselves introduce losses.

@MisterBigDave Год назад

Great video! Exactly what I have tested and vetted out very recently on some new antennas. Perfect lesson!

@davidc5027 Год назад

There are many antenna types that required a trans-match.

@sammiller6631 Год назад

@@charleswoods2996 The ARRL antenna book has other options beyond tuners. Sometimes it's difficult for "some people" like Charles Woods to look beyond themselves. Just sayin'.