actually what is more likely is that you have not compared both antennas as others of us have, i own both do you?if you do not then maybe you should stick to things you do understand!!!!!!!!!! or go buy both antennas and see for your self until you buy both antennas and compare them both at the same height in the same day i would suggest you leave this topic alone.
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better antenna
- Thread starter bluestallion
- Start date
What I've said was I did not test the limits of the bandwidth on the Imax. That's why I was surprised it's wider then normal. Having worked in the broadcast antenna business for 15 years, I understand antennas rather well. That's why I was explaining if your S meter exaggerates the difference between 5/8 wave and .64 electrical length, just add $5 worth of tubing to your Maco and retune the ring tap. Then you have the gain of the .64 wave with the RFI suppression that a true radial system offers. Do you run power into the Imax? Are you testing to a base at least 40 miles out? Did you apply your concept of longer is better to the Maco? Because to some degree you are correct it's just that the change is minimal extended to .64 wave and the Imax is at a disadvantage without a full radial system.
To make that statement means you have no idea who Shockwave is or what he does for a living......there are several members here on the forum who do this every day as there living.
The forum would be a much "user friendly" place if members would just state opinions with out injecting colorful comments in along with there posts......
I have to agree with Shock, the effect of the "proper" ground plane on the 5/8 wave antenna is much less likely to create common mode currents on the feed line than the I Max.....RF current flowing down the OUTSIDE of the coax is a bad thing...because it it radiates! In fact, the amount of radiation from the coax cable is directly proportional to the common-mode current on the outside of the cable.This is a consistent problem with both the A-99 and the I Max and there are many references on the internet to both of these antennas being called "Splatter Sticks"
Length is not always an indicator of a great antenna, if that was the case the 150' + long wire I have in the back yard would "blow smoke" all over my I-10K ground plane...and that is not the case.
Any thing the I Max gains in length, it gives away in its lossy matching scheme in the bottom of the antenna.
Don`t get me wrong, I am not saying the I max is a bad antenna, I am saying that it will not show an significant increase over a 5/8 wave ground plane in the real world when compared on equal terms.
If it is... there are other factors involved other than just the antennas.
73
Jeff
first off audioshockwave you can give a man a badge but that does not mean he will be a good officer.also audioshockwave we are talking about a maco 5/8 and a imax nothing else.shock i do not want to argue with you!shock you stated in the other thread that my imax was not as broadbanded as i stated and you were wrong my imax is workable from 25-to almost 29 and no i dont have to climb and adjust the rings everytime i change my dial.shock i was not running any power when i swapped the antennas out and the stations for reference were 55 and 60 miles.no my imax is not a splatter stick and no it does not come over my computer speakers which are 3 feet from my radio and coax.the top whip i swapped for a 102 stainless and i did pit the maco hub and groundplanes at the feed a couple months ago.shock i think your argument may be with the maco and not me.i would be willing to bet that if the maco was tested along side other 5/8 groundplane antennas it might come in as a under performer.i think maco makes great antennas but they did not hit a home run with this one.shock i started the maco 5/8 to .64 thread and never finished it i could only get 21 feet 9 inches without changing the loop diameter there are several pics and stuff there. all i can say shock is the imax performed slightly better then the maco the only explanation i have is that extra 5 feet of length and HEIGHT was the difference.maybe if i had raised the maco an extra 5 feet so the tips were at the same height the results would have changed but i did not.
I wouldn't say your antenna is a typical Imax and I was using the Maco as a classic example of a 5/8 wave groundplane. Experiment with some more 5/8 wave antennas and you'll see why people would find a 4 MHz bandwidth on this band hard to believe. Being that I hadn't checked that aspect of the antenna I gave it another look and found you were correct. I'm sure that makes you very happy but yet you are acting like we haven't agreed on this point already.
Were you surprised that you couldn't make the Maco work over 21 feet 9 inches with the stock loop? Maybe that is because the stock loop is electrically longer then you thought? The time you spent working on your Imax could have easily been invested into the Maco to make it work as good as the I-10K with less durability and power capacity. Don't be afraid to remove the center bolt in the loop, overlap the ends with zip ties holding them together to find the new shorter length for the matching loop.
Just like your Imax is not stock, my Maco wasn't 100% stock either. It had been tested on many different frequencies including VHF lowband. By the time I got an Imax I had to make my own full length radiator for the Maco and retune it for 11. You don't buy into the myth that the trombone shape of the I-10K gives it more gain then the loop shape on the V-58 do you?
I don't have personal interest in any of these 5/8 wave antennas. I recognize that the maximum gain for the design as an end fed is .64 wavelength with a full set of 1/4 wave 90 degree ground radials. Kind of like what you made your Imax into. The only problem is the Imax matching network is designed to work in the absence of any current flowing in the radial system. Being end fed that increases RFI a lot and decreases efficiency a little.
Since the topic here was a "better antenna" we might as well point out that the highest far field gain vertical omni isn't even in the 5/8 wave family. Spend your time mechanically beefing up the top sections of a Vector 4000 if you want the best performance omni. You can replace the entire radiator with top quality tubing for far less then a I-10K and have durability with a REAL db of far field gain over the best .64 wave.
I also wanted to thank Audioshockwave for the vote of confidence. That can be difficult to earn out here. It's easy to develop too much trust in your local CB shop or to believe misleading results favoring a project you've spent hours working on. One example is a 5/8 or .64 wave with no radials (stock Imax), just the orientation of the coax as it leaves the antenna can easily cause directional effects on the antenna greater then any true gain increase through modification.
i know we did not agree on the other thread but if we do now thats fine by me an i dont care about being correct but i do enjoy my band with the imax has since my radio only covers 25-29 mhz and the maco was not that good.i was surprised that i got that much length out of that maco by playing with that loop and it was at the cost off band width.i will be building a beam for my next project and will get an extra piece to make a smaller loop and try that maco out again with a 23 foot radiator.nice post shock and agree to agree!
ps i thought the lw-150 was longer then the vector?1342, we did not agree about the bandwidth at first because when I tested the Imax I only tried it in the center of the band for comparison. I was sure you were wrong about the bandwidth because it is so ridiculously wide compared to any other 11 meter antenna. The capacitor fed radiator is key to this. Boy was I surprised to find out how wide the antenna really is. That aspect alone has made many happy customers. I will admit the Imax does indeed impress me for it's simplicity to assemble and relatively good performance.
Having correspond with the engineers at Sirio I am also impressed with the design of their new Gain-Master without having tested one yet. This is a radical departure from all of the previous straight stick antennas with the advantages of the Imax in terms of broad bandwidth. From what I gather we are going to find gold a pin SO-239, isolation from the mast within the antenna, isolation of the coax within the antenna, and an apparent increase in performance associated with the simulated center feed and lower TOA. Sirio did file a patent on the design and I have one on the way.
In regards to the LW-150 and the Vector 4000, originally the LW-150 name was given to a decent quality gold anodized copy of the Sigma IV. It is only H&Y electronics that has requested Sirio to re-name their shipments of the Vector to carry the obsolete LW-150 part number. The reality is both Sirio production models are exactly the same. They now have a shorter radiator and longer radials as modeled in CST Microwave Studio.
My tests showed longer radials improved performance and that when doing this you could shorten the radiator a little without losing the performance. That still confuses me but it seems to be the nature of this beast. The silly ball at the top does make it a little longer electrically so that in reality they haven't removed as much length as it looks.
Having correspond with the engineers at Sirio I am also impressed with the design of their new Gain-Master without having tested one yet. This is a radical departure from all of the previous straight stick antennas with the advantages of the Imax in terms of broad bandwidth. From what I gather we are going to find gold a pin SO-239, isolation from the mast within the antenna, isolation of the coax within the antenna, and an apparent increase in performance associated with the simulated center feed and lower TOA. Sirio did file a patent on the design and I have one on the way.
In regards to the LW-150 and the Vector 4000, originally the LW-150 name was given to a decent quality gold anodized copy of the Sigma IV. It is only H&Y electronics that has requested Sirio to re-name their shipments of the Vector to carry the obsolete LW-150 part number. The reality is both Sirio production models are exactly the same. They now have a shorter radiator and longer radials as modeled in CST Microwave Studio.
My tests showed longer radials improved performance and that when doing this you could shorten the radiator a little without losing the performance. That still confuses me but it seems to be the nature of this beast. The silly ball at the top does make it a little longer electrically so that in reality they haven't removed as much length as it looks.
1342 got me thinking about why the stock Maco V-58 is shorter then expected physically. I used this antenna fairly extensively with some of my lowband customers. I always noticed no matter what frequency I tuned the antenna on it was shorter then I calculated. Until someone gave me a V-58 that they burnt the cheap black PVC insulator out in between the two aluminum tubing sections at the base. I replaced it with a solid rod and no overlap in between the tubing on the antenna I tested with.
I never thought about it until now but can anyone else guess what I also removed in the process? Two pieces of metal separated by an insulator, otherwise known as a capacitor in parallel to ground with the radiator feedpoint. In the Imax we have a capacitor in series with the radiator and that electrically shortens it so it can be longer. With the stock Maco it turns out we may have some capacitance in parallel and that would require a physically shorter radiator for the same electrical length.
Right now I can only speculate what impact this could have on performance since I can spot where I inadvertently removed this variable in my tests. In hindsight the stock V-58 may not have been the best 5/8 wave example to compare the Imax against. Does anyone know if the Workman 5/8 wave uses the same type of insulator with overlapping sections of aluminum tubing that form a parallel cap at the base? I see this as a limiting factor for bandwidth and possibly radiation efficiency.
I never thought about it until now but can anyone else guess what I also removed in the process? Two pieces of metal separated by an insulator, otherwise known as a capacitor in parallel to ground with the radiator feedpoint. In the Imax we have a capacitor in series with the radiator and that electrically shortens it so it can be longer. With the stock Maco it turns out we may have some capacitance in parallel and that would require a physically shorter radiator for the same electrical length.
Right now I can only speculate what impact this could have on performance since I can spot where I inadvertently removed this variable in my tests. In hindsight the stock V-58 may not have been the best 5/8 wave example to compare the Imax against. Does anyone know if the Workman 5/8 wave uses the same type of insulator with overlapping sections of aluminum tubing that form a parallel cap at the base? I see this as a limiting factor for bandwidth and possibly radiation efficiency.
shock i heard the workman is identical to the w 5/8 and that antenna would probably perform better with a longer radiator.as far as the trombone on that i10k i think higher gain might be silly but better contact than that maco loop and bent alluminum bracket with that hose clamp is likely.if that radiator could be lengthened and that bracket welded to the bottom of the radiator i think i would be sold.
When i was trying to find a imax on ebay, I found this antenna also. Anyone have one?? How you like it??
SIRIO LW-150 CB BASE ANTENNA - eBay (item 350267896476 end time Oct-16-10 07:57:20 PDT)
SIRIO LW-150 CB BASE ANTENNA - eBay (item 350267896476 end time Oct-16-10 07:57:20 PDT)
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