Is resonance really where you get best antenna performance?

[freecell]

if you haven't seen 0.00J you haven't seen resonance. there's only two ways to proceed, either find the frequency where resonance occurs or change the length of the vertical element to find it. the first method will be easier. we can come back to swr when you find the frequency where (X) reactance = (or most closely approximates) 0.00 ohms. from what i've seen, 5.80 is the closest you've come to it @ 27.200000. resonance hardly if never occurs at a flat 1.0:1 feedline swr. at a low swr yes, not flat.

 

[Handy Andy]

That's the drawback of SWR versus Resonance - the "Resonance" is exactly true at the 1 specific frequency - can't change that either.

But SWR? It is in the Feedpoint.

Put a simple Firestick on a car - using a simple 6" Mag mount and "Thunk" it around on different spots of the car - with the SWR meter to look at it "match" as where it's mounted. The vehicle isn't changed, nor the antenna - but the location of the antenna on the vehicle is different so it changes the Feedpoint impedance at that spot - and changes the SWR at those locations.

So lot of this deals with not just length - but location (as to where it's placed and what it's placed over) so the length can work with the counterpoise image - how well it does that, does affect Feedpoint impedance and therefore SWR changes. .

 

[nfsus]

if you haven't seen 0.00J you haven't seen resonance. there's only two ways to proceed, either find the frequency where resonance occurs or change the length of the vertical element to find it. the first method will be easier. we can come back to swr when you find the frequency where (X) reactance = (or most closely approximates 0.00. from what i've seen, 5.80 is the closest you've come to it @ 27.200000. resonance hardly if never occurs at flat 1.0:1 feedline swr.

It bounces some from -/+

 

[freecell]

for J the (minus) - = capacitive reactance, no sign = inductive reactance. there is no "+".

remember this?
https://www.worldwidedx.com/attachments/20211115_124429-jpg.48392/

 

[nfsus]

for J the (minus) - = capacitive reactance, no sign = inductive reactance. there is no "+".

remember this?
https://www.worldwidedx.com/attachments/20211115_124429-jpg.48392/

If you have a negative you should have a pos. That's where I was going with that. Yes I remember that from yesterday. I took off the addition at the tip and re tuned for resonance. That is where the new pic came from

 

[freecell]

now things are beginning to make sense.

 

[nfsus]

Is it better is it worse?? The way I was taught its worse. But is it

 

[freecell]

"But SWR? It is in the Feedpoint."

Standing Waves are ON THE TRANSMISSION LINE. only two types of resistance and reactance (representing a complex impedance) are present at the feedpoint of the (load) antenna in the case of a non-resonant antenna. neutralizing the reactance at the feedpoint leaves the combined total of radiation and loss resistance at the feedpoint as a pure resistance once (X) reactance = 0. this process is referred to as reflectionless load matching, the other option being to ignore the load and use feedline input matching which can not only satisfy any mismatch present @ the load but also establishes an impedance match of 50 ohms to satisfy the requirements of a fixed 50 ohm output @ the transmitter end of the feedline for maximum power delivery into the line.

 

[nfsus]

Dosent this go into the whole argument that you can fool your meter with more or less coax? So my next question of course is the matching system to maintain resonance but bring resistance down

 

[freecell]

you can fool an swr meter just by increasing and decreasing transmitter power.
let's face it. they're not laboratory grade precision measuring instruments.

you can bring ground / loss resistance down (thereby increasing antenna radiation efficiency) by eliminating losses in your installation. you can also reduce the radiation resistance of the antenna by shortening it but that would negatively impact antenna radiation efficiency. (to actually reduce the radiation resistance you would have to shorten it to make that happen but then, resonance will also shift as a result) in regard to ground / loss resistance the biggest improvement will be seen with a clean & proper mounting location with the feedpoint @ or immediately above a flat metal surface which extends to @ least a couple of feet or more in all azimuthal / horizontal directions and no conducting objects rising above the feedpoint in any direction away from the antenna. that's code for rooftop mount. it'll never perform any better anywhere else.

 

[nfsus]

I wanted to mount it on the roof, but I caught static about it. Personally I think 8ft on the roof of an s10 is awesome.

Now, to get the resonance adjusted I changed the orientation of the spring mount and tilted it toward the toolbox that leaned the antenna more over the cab and hood. Closing the gap between the spring and toolbox lid it would take it into a -j. Also inside the toolbox there is a plate that covers the latching system. Behind this plate is where the termination point is for the antenna. It makes a difference if that cover is on there, even if the lid is already closed.

All I can think is that by adjusting the gap I'm creating a capatience coupling. Without doing that it kept it in the j7 area.

 

[nfsus]

Now the home made astroplane. I decided to check it since I tuned to to swr when I built it. Pic1. Retuned it to resonance then swr. Pic2.

Still on ground atop 20ft mast. Well see.

 

[freecell]

resonance is adjusted by lengthening or shortening the top vertical element. swr on the feedline is adjusted by moving the 13" fiberglas spacer bar up and down between the two legs of the quarter wave matching section. you have to read the patent to actually figure this out, this information is not included in the astroplane owners manual.

without this information and its proper application no one will ever see R=50 jX=0 @ any frequency within the range of the astroplane antenna. the process requires adjustment and readjustment back and forth between the vertical element and the matching section to accomplish this, chances are you've never heard this before. it's all in the patent.

 

[nfsus]

Actually I have copies of the patent the orig paperwork an orig astro few other items. I'm not ignorant to the antenna at all. What I'm inquiring about is the sawtooth in the phase line.

 

[freecell]

nothing about it in the nanovna users manual. search = no results for "sawtooth"

the original avanti astroplane patent with images

https://pdfpiw.uspto.gov/.piw?Docid...&SectionNum=&idkey=NONE&Input=View+first+page