Homebrew Merlin Experiment

[W5LZ]

Marconi,
"Are ya'll telling me if two antenna are equal in resonance, that the actual wave from a short antenna is physically shorter than the wave from a longer antenna?"

Very simply, with some qualifications, yes. A better way of saying it is that the shape of that radiation pattern changes. The same amount of signal is being radiated, it just goes to different places/distances. A good example of that is comparing the radiation patterns of any "full sized" antenna with a rubber-ducky. The same amount of signal can be furnished to the antennas, but because of their physical shape/length, a different 'size/shape' of radiation pattern is produced so that the radiated signal doesn't go as 'far' or in the same directions.
- 'Doc

 

[HomerBB]

Okay, took the cover off the MFJ-259. The solder joint to the coax connector was broken loose. I soldered it back together and put the dummy load on it. It was "good as shootin'" as I've heard them say . . . I put the dummy load on the end of my e1/2λ jumper and it read good, too.
So I can get back to tuning these things with more than an SWR meter and see where it takes us.

 

[The DB]

I didn't start it DB, but I could have misread something.

Just to be clear, has it been said that Homer's dipole, being physically longer than his Merlin, makes a physically longer or bigger wave when broadcast?

The physical length of the antenna doesn't change the wavelength of a transmitted signal. It doesn't matter if the antenna is 11 inches or 2 miles long, the radiated wavelength equals the wavelength of the signal fed to the antenna. What does change with physical length is the radiation pattern of that signal, which is what doc and I were referring to.


The DB

 

[Marconi]

The physical length of the antenna doesn't change the wavelength of a transmitted signal. It doesn't matter if the antenna is 11 inches or 2 miles long, the radiated wavelength equals the wavelength of the signal fed to the antenna. What does change with physical length is the radiation pattern of that signal, which is what doc and I were referring to.


the db

I misread the post then.

 

[BOOTY MONSTER]

so even though the wavelength is the same , with the tips at the same height , the antenna with the longer capture area seems to do better ....... ?

 

[The DB]

so even though the wavelength is the same , with the tips at the same height , the antenna with the longer capture area seems to do better ....... ?

I think someone is trying to put words in my mouth... or maybe doc's mouth... Someone's mouth for sure...

It sounds to me like you are trying to get someone to say that even at the same tip height, the longer antenna is the better antenna... I don't know that I would go that far. In my opinion there are to many variables to consider to go all in on a statement such as that.


The DB

 

[Marconi]

Okay, took the cover off the MFJ-259. The solder joint to the coax connector was broken loose. I soldered back together and put the dummy load on it. It was "good as shootin'" as I've heard them say . . . I put the dummy load on the end of my e1/2λ jumper and it read good, too.
So I can get back to tuning these things with more than an SWR meter and see where it takes us.

Long ago my analyzer did that too, but it just stopped working.

I also found a loose so239 connector was allowing stress on the solder joint and it broke. So I fixed the solder, tightened the connector, and I put a little epoxied on the connector and the case. Tighter than Dick's hat band.

 

[HomerBB]

Been working with the 5/8 today.
I think I'm going to simply make a more traditional 4 radials GP for it. I am not satisfied this one in the photo is as mechanically solid as I want. It is either rebuild or make a full sized one. I'm going with the full sized.

In the photo it can be seen the two of them. Even as it is, with the Merlin higher to the feedpoint by far, the 5/8 is doing better. A full bar minimum on the 2950 face whether local or DX. Receive is easier to read as it is stronger and quieter on the 5/8, but that will be better addressed when I swap their locations before I'm done.

My match is good for SWR, but the GP needs tightening up as I can change readings if I manipulate the radials by hand - they may have developed corrosion sitting behind the shed. I will only put faith in my analyzer readings after I get the new one together.

 

[W5LZ]

This is an honest question. Why is it 'better' to keep the tops of different length antennas 'level' rather than the bases? What's the reasoning behind that?
- 'Doc

 

[The DB]

There is exactly one situation I would test tip to tip, and that is if I were in an area where there was a height restriction and I was going to run an antenna with a tip at that limit.

Outside of that I don't really see any point to it as people will mount their antennas on whatever mast/tower they already have or are putting up.


The DB

 

[HomerBB]

This is an honest question. Why is it 'better' to keep the tops of different length antennas 'level' rather than the bases? What's the reasoning behind that?
- 'Doc

There is exactly one situation I would test tip to tip, and that is if I were in an area where there was a height restriction and I was going to run an antenna with a tip at that limit.

Outside of that I don't really see any point to it as people will mount their antennas on whatever mast/tower they already have or are putting up.

The DB

Because this antenna was manufactured with an apparent expectation that it be mounted for the most performance potential with the tip at the same place as the antenna it is replacing I thought it good to test in that particular position to see whether it delivered.
Whether or not this was because of height restrictions as the AP was designed to deal with is not anything I've read or heard, but I'm not afraid to offer the Merlin that chance to strut its stuff.

Had I tested it at the same feedpoint elevation first many would step up to say the longer antenna was given an unfair advantage. It is a short antenna from the coax connector up. So, I have reversed the argument in favor of the Merlin for now. I think that the advantages will be with the best design no matter what, so I will try it like this, and if the Merlin should emerge on top this way then we can go to same feed point heights.

Under most circumstances I agree that folks just take one antenna down and put another in its place. I have no argument against that. I have been told this:

I disagree (with tip height comparisons) . . . In order for performance comparisons to be technically valid they must be tested to a control, and that long accepted control is feedpoint height above ground. Promoting manufacturers recommended install procedures as being essential in measuring performance is altering the baseline control. In this case effectively changing the control to 'tip height above ground'. Changing the measurement criteria for different antennas gives no valid comparative data, shifting the measurement ball-park is a marketing departments domain.

This antenna was seemingly made to compete in areas with restrictions on antenna tip height (thanks for the info wa10). This is fair enough, but performance measurements according to their install instructions is only valid in that restricted environment, not globally. And these pivotal points are what I tried to get across in my previous post.

I applaud your efforts constructing and looking at antenna performance from different angles, but without a standard measurement control you must expect contention."

A perfectly legitimate response, and point taken, but I still think that until I answer the questions surrounding this mythological antenna at least for myself there will always be protests against whatever conclusions I come to.

I do believe this antenna is a perfectly good option, but beyond that I have not decided.

 

[Marconi]

This is an honest question. Why is it 'better' to keep the tops of different length antennas 'level' rather than the bases? What's the reasoning behind that?
- 'Doc

If you guys re-read the 2nd post in this thread by Booty Monster, you'll see where he posted the assembly instructions for the Merlin. Some of the rest of this thread was discussing the meaning of the 1st paragraph, and how the first claim was worded. That simply being an idea for a restricted antenna location...like Avanti also claimed years ago, and that DB mentions above.

Probably if I had not talked about this idea several years ago in regards to comparing the A/P to some antennas that are 20' feet an longer, the subject would likely have never come up.

The old A/P is gone, and the New Top One gets little to no conversation. Sales are probably poor as well, and that is likely due to all the CB BS on truck stop restroom walls.

IMO, the A/P and the new version by Sirio is a really good antenna, and can perform about as well as any CB antenna I own. Depending on its height, maybe it won't always make the biggest signal, but I don't think you'll miss a contact due to the little difference I've noted in real world comparisons and with my modeling.

IMO, such discussions can shed some light on some misconceptions that have been repeated like a parrot talking about the A/P for years and maybe help explain why the claims were ever made, but I think I'm safe in saying my words will never convince anybody...that won't pay attention or consider other ideas.

I echo Homer's comments while I was making my post. I also think Homer is interested in understanding design, and to test what he can in that vain, so I tend to cut him some slack.

 

[W5LZ]

You've answered my question.
- 'Doc

 

[HomerBB]

. . . I also think Homer is interested in understanding design, and to test what he can in that vain, so I tend to cut him some slack.

Yep, you know me. . . jest a little odd . . .

 

[BOOTY MONSTER]

This is an honest question. Why is it 'better' to keep the tops of different length antennas 'level' rather than the bases? What's the reasoning behind that?
- 'Doc

There is exactly one situation I would test tip to tip, and that is if I were in an area where there was a height restriction and I was going to run an antenna with a tip at that limit.

Outside of that I don't really see any point to it as people will mount their antennas on whatever mast/tower they already have or are putting up.


The DB

very rarely do i see a omni cb antenna guyed . most folks seem to put them up at what ever height they can get the mast up to on the side of their house or tree . FWIU the FCC hasn't enforced the CB antenna height rule in decades ... if ever . i doubt very few of those folks would put a taller antenna on a shorter mast/feed-point unless it violates a HOA rule and the HOA strictly enforces their rule .... or they knew or suspected that the shorter omni was gonna do better than the taller omni . example ..... i expect a penetrator 500 or a gainmaster to do better than a taller imax 2000 ....

homer , at some point can you compare the merlin vs. your vector homebrew with their tips at the same height ? i'd expect a RF bloodbath with similar feedpoints ..... just saying .