Question methods of lowering SWR

[roadrage]

So if the physical size of the antenna doesn't matter, than why isn't everyone using Little Wils and K30s? If there is no noticable difference, why would anyone deal with the height restrictions and whacking tree branches? Maybe I am misinterpreting your input, but are you saying that having 40% more surface area of antenna surface than a Wilson 1000 and no efficiency loss of the loading coil on the 102" that there is not going to be a noticable difference in performance and I am waisting my time?

 

[W5LZ]

The shape/size of the radiation pattern of an antenna is primarily determined by it's physical size/length. If you change the size/length of an antenna then it changes the radiation pattern.
A typical 1/4 wave length vertical is desirable because of it's radiation characteristics and because it isn't too difficult to make it match impedance with the rest of the system. For mobile antennas, it's usually the most practical size to use. It's radiation characteristics are known so it's also what's commonly used for comparisons. If you make changes to that length of a 1/4 wave antenna you have to expect there to be changes in it's performance in where it will put a signal, it's radiation pattern. Small changes in length mean small changes in where that signal goes. Large changes in length mean larger differences in where that signal goes. When the change in where the signal goes becomes objectionable, then -usually- it's because the signal isn't going where you want it anymore, the @#$ thing's too short. [That also works in the other direction, it can be too long.]

You can make almost any length of antenna work if you want to bad enough. It doesn't mean that it would be all that usable/practical, but that depends entirely on what you want to do with that antenna. I've seen a bulb from a flashlight used as an antenna between two vehicles traveling together. They could hear each other fine, but very few other people heard them at all.
'Size' does make a difference with antennas...
- 'Doc

 

[WA8ZYT]

One thing I did not see in any of the above posts, and I just breezed through them rather quickly:

Beating your brains out to get an antenna's swr from 1.5 to 1 down to 1.1 to 1 is pretty much a waste of time. The person on the other end is NOT going to notice a difference.:bdh:

If it's 2:1 or better, it's livable. I like to see 1.1:1 myself, it's just a physiological thing with us radio folk.

 

[roadrage]

One thing I did not see in any of the above posts, and I just breezed through them rather quickly:

Beating your brains out to get an antenna's swr from 1.5 to 1 down to 1.1 to 1 is pretty much a waste of time. The person on the other end is NOT going to notice a difference.:bdh:

If it's 2:1 or better, it's livable. I like to see 1.1:1 myself, it's just a physiological thing with us radio folk.

My amp had a meltdown. I want to make sure it doesn't happen again. I will say that I have learned a ton about antenna theory in the past two weeks. So if anything, it is worth it for that fact alone.

 

[AudioShockwav]

Beating your brains out to get an antenna's swr from 1.5 to 1 down to 1.1 to 1 is pretty much a waste of time

99% of the time I would agree with you, but there are some of the CB guys that are running there equipment on the ragged edge, high drive levels and over-volting the transistors in the final amp sections to squeeze every last single watt out of each transistor.
Kind of like guys that over-clock CPUs and run liquid cooling in custom built gaming computers.
In cases like this, reflect can help speed the destruction of the transistors, so they put a lot of effort into getting reflected power as low as possible.
It is mostly the "key-down" crowd that go to extremes like this.
On the Ham Bands I sometimes run into loads of 2.5:1 and do not even break a sweat, but under much different operating conditions.
This is the CB section, different conditions.

73
Jeff

 

[roadrage]

99% of the time I would agree with you, but there are some of the CB guys that are running there equipment on the ragged edge, high drive levels and over-volting the transistors in the final amp sections to squeeze every last single watt out of each transistor.
Kind of like guys that over-clock CPUs and run liquid cooling in custom built gaming computers.
In cases like this, reflect can help speed the destruction of the transistors, so they put a lot of effort into getting reflected power as low as possible.
It is mostly the "key-down" crowd that go to extremes like this.
On the Ham Bands I sometimes run into loads of 2.5:1 and do not even break a sweat, but under much different operating conditions.
This is the CB section, different conditions.

73
Jeff

Yes.

Being new to the amp scene, I am guilty due to ignorance. I did a bunch of research but it isn't always enough. I wrongly put faith in the advertised input specs of my amp. I wasn't trying to squeeze anything more than what I thought the amp was supposed to do. Don't laugh at me, but I actually turned my dk down a little lower than what was specified to "be on the safe side." That was obviously foolish because the amp didn't last at all. I am not faulting anyone but myself. I could have easily read the data sheets and said that the input and output claims were nuts. From now on, I am running input to the transistor data sheet rather than the amp manufacturer's spec. Still, as I am not a person with much money to throw around, I am still tweeking my system to make it as good as is possible. It may not give me any noticable difference, but it helps me learn about antenna systems and how they work. Plus it gives me a little piece of mind for when my amp gets back.

 

[AudioShockwav]

I am guilty due to ignorance. I did a bunch of research but it isn't always enough. I wrongly put faith in the advertised input specs of my amp. I wasn't trying to squeeze anything more than what I thought the amp was supposed to do. Don't laugh at me,

No laughing here, and i would replace the word ignorance with inexperience.

You did what many others do, no one knows it all on day one, and the ones that ask questions are the ones that get the most out of the hobby.

That is the idea with the WWRF, people who like to play radio helping people that want to play radio.

73
Jeff