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Gizmotchy 5 element boom
- Thread starter Zman
- Start date
most likely have to add a couple more elements to accomplish the same performance with respect to FB ratios.
Hello,
If you can provide the present element lenght and diameters(over which length)/distances...
Im sure there will be some one who can put your antenna in some software and get some results.
In aspect to more boom length.
Boom length equals gain.
It would be fair to say You can expect a advantege in gain.
The "standard" rule is: if you double the boom length you "gain" 3dB.
Often it is true, that if you "add" something at one point there is a drop somewhere else.
However, your original boomlength is....well...
I think i have designed at least 100 different 5elements yagi's, but never on such a short boom length.
Your doubts conserning the boom length is one that i share.
16 feet seems indeed rather "short" for a 5elements.
Im not saying it cant be done, but i am quite confident one can get the same or better results with only 4 elements.
Most "owa" designs (pse google owa yagi antenna to find out what it indicates)
have a boom slighlty longer...say around 18 feet.
And owa designs are also known for having a relative short boom.
Your idee to extend the boom to say 24 feet is certainly advisable.
Not only will be the gain be improved but this kind of lenghts are often used and have provided "good" overall performance from a 5el.
So, all in one...yes go for it! but one who migth help you needs to have dimensions and lengths to "optimize" your system.
Kind regards,
Henry HPSD
19SD348
www-dx-antennas.com
If you can provide the present element lenght and diameters(over which length)/distances...
Im sure there will be some one who can put your antenna in some software and get some results.
In aspect to more boom length.
Boom length equals gain.
It would be fair to say You can expect a advantege in gain.
The "standard" rule is: if you double the boom length you "gain" 3dB.
Often it is true, that if you "add" something at one point there is a drop somewhere else.
However, your original boomlength is....well...
I think i have designed at least 100 different 5elements yagi's, but never on such a short boom length.
Your doubts conserning the boom length is one that i share.
16 feet seems indeed rather "short" for a 5elements.
Im not saying it cant be done, but i am quite confident one can get the same or better results with only 4 elements.
Most "owa" designs (pse google owa yagi antenna to find out what it indicates)
have a boom slighlty longer...say around 18 feet.
And owa designs are also known for having a relative short boom.
Your idee to extend the boom to say 24 feet is certainly advisable.
Not only will be the gain be improved but this kind of lenghts are often used and have provided "good" overall performance from a 5el.
So, all in one...yes go for it! but one who migth help you needs to have dimensions and lengths to "optimize" your system.
Kind regards,
Henry HPSD
19SD348
www-dx-antennas.com
I agree and I think the Maco 105c is at least minimally optimized, and I believe they work quite well...if you have the space and can get the boom above 25' feet.
I have a Gizmitchy dual polarity 3 element and just got the booster kit (extra element kit) Fiday from UPS Ill do this addon in the next few weeks I love the 3 element and Im sure the upgrade will be just as nice. Ive got a few beams and this Gizmotchy is my favorite but if I ran anyother one it would surely be my Maco shooting star 4 element dual polarity beam (Same company) 
Well wavrider I agree, I've used the Maco 105 design on a HyGain Long John as and alternative once, and I still wasn't impressed with the 5 element at my location, which is tight.
I concluded a 5 element just would not work as well as it could here, and that was likely due to space limitations I have around my place. However, I did think the Maco spacing did hang right with the HyGain design...in their working results. So, I'm just not convinced that optimization is the best at all locations.
Personally, with all the work I've done with my beams, I never found optimize settings to be of a benefit to me. IMO, the old standard spacing designs, that shows a more well balance distribution across the boom, are better. Maybe that has to do more with my comments above regarding limitations.
Therefore, I believe the design spacing for the Moonraker and the Giz, a more well balanced and narrow spacing design...can work better at some locations, like my place.
Your mileage may differ.
I have a Gizmitchy dual polarity 3 element and just got the booster kit (extra element kit) Fiday from UPS Ill do this addon in the next few weeks I love the 3 element and Im sure the upgrade will be just as nice. Ive got a few beams and this Gizmotchy is my favorite but if I ran anyother one it would surely be my Maco shooting star 4 element dual polarity beam (Same company)
I have the Gizmo set up in the backyard as of today and it is set up as the 4 element. I started out as the standard 3 element Gizzy and added the extra "booster" and i found out it changed the SWRs big time from the 3 element settings... I manage to get it down to a 1.2-1 all 40. So not bad but im wondering if i added the 5th element what it will do. I might just add the extra boom and keep it as a 4 element and see what it will do with the elements spaced like my moonraker 4...
Do you know how long the boom for a new kit is? Never mind I see you already have an add on kit.
Well i got the last elment on the boom and so far so good. Nice low SWRS across all 40. I did put my MFJ 259 analyser (HIGHLY reccomended for antenna tinkerers!) and i noticed the antenna seems a tad narrow banded in relation to my old, crusty, beat to heck, Moonraker 4i get a 1.2=1 on CH 1 and a flat match on 20 and a 1.2=1 on 40 but the swrs rise quickly above about 27.505. The flat side is somewhat the same but it still rises above 27.505.