5/8wave workman swr issues? Balun? Unun?

[The DB]

Guys don't leave in this antenna nightmare! The more I read the dumber I get??

Your not actually getting dumber, you are just realizing how much you don't know.

This antenna theory is hard on my brain Dx. Is the main purpose for all this head scratching .... This antenna will be mounted at the water (saltwater)line during use at 10-20 feet....looking to get a lower radiation pattern to work Dx from the beach.

Here is a link to a thread that is a sticky up in the HAM antenna section, it talks about take off angles. It is a good read.

The Myth Surrounding Antenna Take Off Angles

Making the antenna electrically a 3/4 wave for resonance and 5/8 wave for the radiation pattern? Is think ? Is this what is being attempted? I understand past .64 wave antenna pattern break up into many lobes and nulls....I want as low a radiation take off angle with the majority of the radiation in that low angle Lobe? Correct?

This is how it is done. Think of it like a 4 foot car antenna, it has a coil/matching network to keep it resonant as a 1/4 wave antenna, yet the antenna is much shorter than 1/4 wavelength. The actual length of the antenna and not the electrical length at a frequency determines the radiation pattern.

Radials....mine measure 102 inches. Would a be better to add another radial ring below the ones currently on the antenna...I have the parts and tubing.(ended up with 2 of these antennas?). Would this be the same as folks adding 120 wire radials to some verticals?

Ground mounted verticals need all of those radials. As the actual ground (as in the earth) makes a very inefficient ground plane, those radials are used to increase the conductivity of that ground.

In your case, with raised radials above a few feet off of the ground, it will make far less difference. You can add them, and they shouldn't hurt anything, but I don't think you will get much of a benefit from them either. That being said, if I had them I would likely put them up anyway. They will increase the wind drag load on your antenna, if you see that as a drawback. As another drawback you may have to adjust the radial length some as the radials do react with each other when it comes to tuning, and you have more then the original design specs.

I thought the mast would be the other half such as a dipole. Some models I have. Found on the web show the mast and feedline radiating? I have thought about adding wire radials around the mast laying on the ground but reading these must be a certain wavelength and would not be worth all the tuning....I can't get a simple antenna to tune so adding issues is the wrong way to go.

The other half of the antenna in your case are the radials. One thing they are supposed to do is help decouple the mast/wire below them from the antenna.

You will note with a dipole that both sides are tuned lengths. A mast is not, I suppose you could try and tune the length of the feed line with a choke at an appropriate point. Also, the radiation from the mast/feed line in most setups works counter to the radiation from the antenna.

ghutch, did you read the instruction DB linked to for you?

My linked instructions?

Did you mean:

ghutch, here is a instruction sheet that was reportedly produced by the premiere installer of antennas, world wide, and beyond, Master Chief and he tells us so in the first sentence.

View attachment 8457

Odd, when I quoted it it changes the name on the attachment... It should have said "Master Chief's Instruction on the V58.pdf", maybe it will update itself.


The DB

 

[ghutch]

I want to get 1-1 swr .... It can be done I think. May take a bunch of testing and re testing.
I actually got a slight bit lower swr at the beach and couple days back....took it apart re set up in the drive and the swr changed with the same antenna set I had at the beach....different ground and area. I know this would change the swr but had zero luck moving and re testing various lengths and tap points on the tuning ring. If the ring adds or sets resonance at 3/4 wave would the measurements be the radiator toal length plus the coil length give or take and inch or two?? Equal 3/4 wave ?? Or stated another way, total length of radiator+ the coil length equals= 3/4 wave in feet/inches
Take off angles are touted as the all important Dx tool of all Dx tools? That why i chose the vertical antenna to use at the beach....mast height is an issue I have no beam, so wanted a low TOA. Verticals at low heights are taked about as having a lower TOA than a horizontal antenna at low heights?? While looking at beam patterns I note some nulls are in a low take off area so any Dx coming from that particular angle would be unheard or weak....say for example you would have a major lobe at 12 degrees and work Dx at that angle of arrivial then a null at say 14-16 degrees. Signals arriving at these low but null pattern angles would go unheard. Or be weak copies. With these things in consideration a beam would be better for Dx with a relatively low angle of departure and a larger active lobe say from 10 degrees to 20 degrees without any null such as a vertical pattern has ?? I seems to me verticals would be a better Dx antenna with the exception of not having the gain and being able to be turned thus attenuating signals from some angles. Power could make up for the gain? To some degree....use 300 rather than 50 would get the same gain as a 3 element beam?

 

[The DB]

I'm done, enjoy your setup.


The DB

 

[BOOTY MONSTER]

power can give you more tx , but it can't give you more rx . all antennas are compromises in some way . a beam and omni seems to be the effective route , but most of us can't/won't do that for various reasons .

 

[jazzsinger]

I want to get 1-1 swr .... It can be done I think.

Why?

what your aiming to achieve is pointless, have you any idea how many idiots have died in the past 4 decades falling off roofs/towers trying to achieve this mythical achievement.

heres the straight fact, no cb bullshit.

yes 1.0:1 vswr can be achieved, but only on one single frequency, as soon as you move from that frequency reactance changes the vswr, just because cb swr meters (infact swr meters in general) are too innacurate to read the tiny change in swr ratio from say maybe 1.0:1 to 1.00001:1 doesn't mean it hasn't happened.

second point most swr meters are analogue volt maters, which for the most part read most accurately in the centre region of the scale, look at the markings on it, they aren't so close together/compressed at one end as the other and the middle has most equal division of scale, this tells you it isn't linear therefore won't be as accurate at all points.

most transceivers will easily tolerate a 2.0:1 mismatch without much change in performance. many will tolerate 3.0:1, transceivers with the motorola mrf 477 final were capable of facing into 10:1 vswr due to the rugged design of the motorola device.

if i go in the car for a short time out mobile, and i key up on the magmount and my swr is 2.0 or 3.0:1, am i f@ck moving my arse to make it slightly better, i've never blew a linear in my life or an output transistor, i'll still sit and confidently call anywhere on the planet when skips running.


here's the point all the guys are getting frustrated trying to tell you,

vswr just isn't that important, perfect vswr is a myth, just like antron A99's 9.9 dbi gain.

spend more time on the radio,less time dicking about with the antenna, quality dx doesn't require perfection and as a bonus you'll find life less stressful.

 

[HomerBB]

ghutch, did you read the instruction DB linked to for you?

My linked instructions?
Did you mean:

ghutch, here is a instruction sheet that was reportedly produced by the premiere installer of antennas, world wide, and beyond, Master Chief and he tells us so in the first sentence.

Attachment 8457

Odd, when I quoted it it changes the name on the attachment... It should have said "Master Chief's Instruction on the V58.pdf", maybe it will update itself.

The DB

Yes, I made a mistake. I meant to refer to Marconi's link. And when I copied and pasted it I did not copy the title of the article.

To Jazz's point, I do not mean to express frustration: it ought to be apparent that I work on my antennas to the point of frustration trying to achieve the best match. There is a point that accepting what can be done must be arrived at, esp if it is not of consequence between the goal and the result.
When I work on it the most is when I am building it myself. I have greater control over the mechanical design, so being able to manipulate the antenna is a perogative I would not have that level of control over with a manufactured antenna. In fact, just this week when working on an antenna of my own manufacture I changed the location of where I had my matching section, and I tossed out the current matching section for another modified version as I wasn't happy with it. On the other hand, I have a fist full of mobile antennas I did not make, and when I put them each on my vehicle on the same puck mount on the roof some of them I can get a better (lower?) match on than with others. Given the limits of each antenna there is a point that I can do absolutely nothing about it and accept what I can get. The antenna I am currently having the most consistent results talking DX with from the mobile is one that has the lowest SWR at 1.5:1. The other end of 40 channels is 1.7:1. I leave well enough alone and talk from coast-to-coast and over seas, too.
Do I want lower? Of course. Is it necessary? Nope. Would I run an amp like that? Yep, I sometimes do - 100/200 PEP.
Some of those antennas have tuned lower than that on the same vehicle - when on the fender, or when sitting on a different spot on my roof. It's that simple. In a given location with parameters in the environment and within the antenna you can't control you sometimes accept what is possible and get on with having fun.
If I can help I will, but it seems to me you already have a great antenna that can give you years of communications pleasure.

 

[The DB]

power can give you more tx , but it can't give you more rx . all antennas are compromises in some way . a beam and omni seems to be the effective route , but most of us can't/won't do that for various reasons .

This is absolutely correct. You can transmit a million watts out, but if you can't hear the remote location you cannot make contact. Communications are a two way street.


The DB

 

[The DB]

spend more time on the radio,less time dicking about with the antenna, quality dx doesn't require perfection and as a bonus you'll find life less stressful.

Best advice in this thread so far.


The DB

 

[Beetle]

Not exactly. While this effect happens, what is actually happening is they are making the antenna electrically a 3/4 wave antenna. 3/4 wavelength is resonant. The resonant point of an antenna is also the low impedance point of that antenna, so in a round about way the effect you see happening is the same. However, very rarely is the best point to tune these, or any antenna for that matter, at 50 ohms of impedance.
The DB

Had to comment on this earlier post. Resonance has nothing to do with impedance. Consider a half-wave, Mark I Mod 0 dipole for 40 meters, cut for somewhere around 66 feet overall. It will be resonant (meaning that inductive and capacitive reactances are equal and opposite, cancelling each other out at that particular frequency and leaving only radiation resistance to represent impedance. This radiation resistance probably won't be exactly 50 ohms; it depends on antenna height, proximity to trees, buildings, power poles and a dozen or more other unknowns.

Now then, if we try to use this same antenna and feedline to work on 20 meters, guess what? The antenna is still resonant (meaning zero net reactance) at twice the frequency, but the radiation resistance is through the roof - likely in the thousands of ohms. A quick check of things with an antenna analyzer will show this.

BUT, the same antenna will work quite well on 15 meters (three times the frequency the dipole was actually cut for). It will show a low value of net reactance (theoreticaly zero), and an impedance will within most equipments' ability to work with.

 

[The DB]

Had to comment on this earlier post. Resonance has nothing to do with impedance...

Nothing to do with impedance? Why is it then when you build an antenna there is a dip in impedance at the resonant points? As you approach a resonant point the impedance in the antenna drops, and after you pass resonance impedance then goes back up. At the resonant point there may be 5 ohms, 120 ohms, 600 ohms, or any other value. I only stated that at resonance it will be at its lowest impedance. I have seen this multiple times with multiple analyzers over the years on both antennas I have built and tuned for myself and others. To say they have absolutely nothing to do with each other is simply not true. And just to make sure we are on the same page, I'm talking about the impedance of the antenna itself. This has nothing to do with a transmission line.

Take a look with an Antenna Analyzer that graphs the various functions. You will see the low impedance point consistintly line up with the resonant frequency.

The rest of what you typed is true, the same antenna is resonant on every frequency you mentioned, and more. 80 meters for example, it is a (or very close to) quarter wave antenna, and it should still be resonant.


The DB

 

[W5LZ]

The DB,
Sorry, not true at all. Don't confuse radiation resistance with impedance.
Use a 1/2 wave length antenna that's resonant. If fed in the center the input impedance should be in the neighborhood of 50 - 75 ohms. If fed at one end, that input impedance will be in the neighborhood of 1000+ ohms. The radiation resistance of that 1/2 wave length antenna has not changed, neither has it's resonance.
How about the input impedance of a 5/8 wave vertical antenna? It's input impedance isn't 50 ohms by any means until it's been matched by an impedance matching device of some kind.
That radiation resistance is -part of- input impedance and it's value is almost never 50 ohms or really close.
- 'Doc

 

[The DB]

The DB,
Sorry, not true at all. Don't confuse radiation resistance with impedance.
Use a 1/2 wave length antenna that's resonant. If fed in the center the input impedance should be in the neighborhood of 50 - 75 ohms. If fed at one end, that input impedance will be in the neighborhood of 1000+ ohms. The radiation resistance of that 1/2 wave length antenna has not changed, neither has it's resonance.
How about the input impedance of a 5/8 wave vertical antenna? It's input impedance isn't 50 ohms by any means until it's been matched by an impedance matching device of some kind.
That radiation resistance is -part of- input impedance and it's value is almost never 50 ohms or really close.
- 'Doc

Ouch, leave it to be the one time I'm in a hurry and don't proofread my text is when I screw up. Change those two times I typed "radiation resistance" to "impedance".

By the way, where did the 50 ohms come from, I never said that specific impedance had anything to do with resonance, not once, ever. As a matter of fact I listed three possibilities (none of them 50 ohms and they were randomely chosen but possible depending on the antenna), and I included the text:

...or any other value.

I have specifically gone out of my way to not imply a 50 ohm impedance is in any way shape or form connected to resonance, and have never once made the claim. I said that earlier in this very thread as well as several others. ANY association with 50 ohms of impedance, resonance, and myself is in error. You have seen plenty of my posts in the past doc, you should know me better then this by now.

I merely stated that a resonant frequency (and for that matter near resonant frequencies can as well, although I did not include that) of an antenna presents a lower impedance then a nonresonant frequency. That is all. I never once said that an antenna could not have more than one resonant frequency. I never once said that different resonant frequencies would have the same impedance. I never said that different ways of feeding a resonant antenna length would have the same impedance. Please, if I ever made any of these claims find it and quote it to me.

What did I suddenly become a politician or something? If I did I hope it pays better then my current job... Maybe I can vote myself a raise or something...

So lets take the largest resonant impedance listed, the end fed half wave antenna can have 1000+ ohms of impedance, so what is the impedance if the resonant frequency of the antenna is 3Mhz off of the frequency you are using? I'll let you guys figure it out from here...

Edited the previous post to say what I meant to say in the first place.


The DB

 

[W5LZ]

I can go along with your revised statement.
- 'Doc

 

[Shockwave]

I'm thinking there are examples where tuning for "the dip in impedance" may not put you close to resonance. Take any antenna that uses an inductor at its base with a tap point on it that connects to the feedline. Could be anything from your Wilson 1000 mag mount to your Maco V-58. These matching networks are nothing more than RF versions of the basic auto transformer.

The closer you move the tap point towards the grounded side of the inductor, the lower the impedance will be. You could continue to lower the impedance until you've reached a short. You want the impedance to match the feedline but that doesn't guarantee resonance has been achieved either.

You could take a center fed gamma matched dipole such as the Sirio S-27 and adjust its elements length so that it was no longer resonant. At the same time you could adjust that gamma match to show a wide range of impedance including 50 ohms without resonance.

 

[The DB]

I am opting to move part of this discussion to a new thread as it is getting a bit off of what the op was asking about.

The new thread can be found here.


The DB