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Discussion Starter #1
On this rainy lousy day (my birthday), please let me introduce to you my new build called CEB 4 bay antenna. CEB for Chubby Easy Build :rolleyes:

The 4 bay antenna is made of 8 lengths of 7 inch aluminum tubes (1 inch O.D.), 4 lenghts of 7 inch PVC rigid conduit (1/2"I.D.) and 16 rivets.

Made 4 grooves on the PVC spine and glued the four 7 inch PVC conduits. The phase lines are made of 14AWG electrical wire. As you can see on the pictures, the 16 rivets are holding the tubes together and 8 of those rivets are holding the phase lines.

As for OTA reception, it's as good as the bowties and I still get real channels 14, 22, 32, 38 and 43 at 86 miles. Forget about Balm's channel 13 ;) Did not have time to check the quality of the signals.

Compared with the bowties, this antenna used with the same reflector (20" wide) has a narrower beam width. So an 18" wide would be needed for a wider beam or 24 inches to make it more directional.
http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id=267eee22a6d100



 

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Happy Birthday!

Hey! Nice simple structure! Good job... I don't think I"ve ever seen anything with straight horizontal bay elements modeled.

CEB = Chubbtenna :D

It would be interesting to see the effect of having 9" elements at the top and bottom bays with the 7" elements in the middle bays. Maybe 13RF would be possible.

________

Edit:
Second thought!,... 29" narods placed 1/2"above the top elements and 1/2"below the bottom elements would likely produce some VHF enhancements.
 

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Discussion Starter #3
Thanks Ota_Canuck,

That was one of my thoughts when I built it, because 2 times 7" is near the quarter wave length (λ/4) for RF13.

As for 9" mixed with 7", just sorry to deceive Balm again.

AntennaCraft U1000 and Winegard HD 4400 have horizontal elements, don't know if they were modeled. With chubby elements it's another ball game.
29" narods placed 1/2"above the top elements and 1/2"below the bottom elements would likely produce some VHF enhancements
That I can try this week.
.
 

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The bowtie is supposed to provide more bandwidth than a dipole.
Yes, but FAT (relative to the wavelength) dipoles behave like bowties.

The 4 bay antenna is made of 8 lengths of 7 inch aluminum tubes (1 inch O.D.), 4 lenghts of 7 inch PVC rigid conduit (1/2"I.D.) and 16 rivets.
Post the other dimensions, so it can be modeled. :D

The reflector to element distance looks extremely short, but that could be an optical illusion.
 

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300ohm, are you planning on doing nec modeling this?

What do you think about adding 29" narods?

Those straight horizontal elements vs wiskers? The only downside with straight horizontal bays is that it becomes an eight-seater for birds:p Can it be modeled with eight birds? ;)

And,... should those elements be lengthened closer to 8" to avoid extending into the 700Mhz+ ranges?
 

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What do you think about adding 29" narods?
It might work. In fact, maybe even 4 NARODs, (one per dipole) would work and give even more vhf-hi gain.

Also using wider reflector rods like on a regular 4 bay bowtie should also provide vhf-hi gain.

And,... should those elements be lengthened closer to 8" to avoid extending into the 700Mhz+ ranges?
I would think so. Maybe even 9 inches.
 

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The combination of the terms "CEB" and "Bay" are unfortunately spoken-for in the technology world:

http://en.wikipedia.org/wiki/SSI_CEB

so we need to come up with a different name for Bouval's creation. I like the "Chubtenna" name :D but before I saw that I thought about how the tubes remind me of Cuban cigars, so my vote is for calling it the Cigar 4. :)
 

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Discussion Starter #9
Tubo 4 Antenna !

I went to Cuba 37 times so I'd call that antenna Havana 4 or Tubo 4 ;)
http://voyageforum.com/v.f?membre=grandsage;
Using aluminum cigar tubes would work but would be kind of flimsy.

As for longer elements then 7 inches for UHF Low, I'm not sure about that. Using those huge tubes compensates for the lenght. Getting RF14 86 miles away means a lot.
.
 

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Discussion Starter #10
300ohm,

Reflector size 20" wide by 33.5" high, 19 rods total. 16 rods .25" and 3 of .375". Rods are spaced 1.875" ctr to ctr.

Bay spacing 7 inches

Horizontal space between element tubes is 1.75"

Reflector to elements spacing is 2.875". OK I know it's short, but I can try it later in front of my shed's metal door.

Thank you for being interested.
.
 

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Bowtie Element Theory also applies to this one

According to antenna theory, each metal tube (half a bay) is essentially the same as the two wire elements of a bowtie bent to be parallel, so while we see the elements as 3D tubes, they are actually represented almost perfectly by two wires. BOUVAL's antenna "re-replaces" the bowtie made of only upper and lower edges with a solid metal shape.



As for how this metal tube antenna compares in performance to a similar maclap M4, that will be interesting to see. According to theory, in the case of conventional antennas like the M4 each bowtie represents the upper and lower edge of an invisible cone. The cone shape is desirable for UHF broadband reception, while the tube shape of BOUVAL's design will only have a peak at a certain tight range of channels, which will be shiftable by changing the separation of the upper and lower edges. Given that it is a UHF-band antenna it is not so critical a peak as in certain channel-cut designs, so that would explain why other UHF channels are picked up as well.

The best benefit of BOUVAL's design is that the metal tube elements retain their shape while two wire elements could be bent or mis-shaped by birds, weather, bad golfers, etc. but the tubes have the cost of a bit more wind resistance and/or snow load.
 

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Pros & Cons ?

Stampeder? Bwahhhh! Bad Golfers! :p now that was funny!
__________________________

Other benefits of this tube design,..
[if chubby elements do prove to compare to 'basic M4' and/or '4bay' performance]
-Simplicity for novice builders
-Strength of rigid elements

Also,.. if alum tube is not readily available,.. then 'galv conduit' or thin walled '1/2 copper pipe' could be used for the driven chubby elements. Smaller diameter materials would physically help reduce weight and loading issues. Though variables of material diameters may also produce pros or cons regarding overall reception performance.

Stampeders theoretical [edges] pic shows an open end element,.. whereas each tube element may function as a closed rectangular element [such as a reversed slot antenna]. If so, then would this antenna be more usefull as mounted horizontal or vertical? My thought is that the end feed point would produce the effect of a closed rectangular wire element.:confused:

This could be quite valuable as a simple Bi-Directional solution for those who just want all round suburban/ local reception.
 

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As in the 2-wire model of a solid cone, the 2-wire model of a solid pipe does not have a joining vertical end that closes it into a loop because it will have no effect on the model.

Again, just to keep this clear, the tube diameter will directly affect which UHF channel(s) will be peaked, so BOUVAL's design can actually be tuned in the design phase. Having said that, the UHF band is very forgiving for such an antenna so the results will not be as severe as with a channel-cut yagi or other such single channel design.
 

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RE: "elements as 3D tubes"

Stampeder refers to the term 3D which has been used on various swept element designs for performance enhancements. Adding a third dimension in other designs such as M4 and the SSH antenna have added a whole new world of controls for beamwidth coverages and may also influence the overall bandwidth frequency range.
 

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ota_canuck said:
Bad Golfers! now that was funny!
The only good thing I can do with a driver is use the metal shaft as an antenna element! :D
ota_canuck said:
Stampeder refers to the term 3D which has been used on various swept element designs for performance enhancements.
Now you've got me thinking of a variant of BOUVAL's design using bicycle handle bars! :D
 

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Being that this tubing is quite large with open ends, I'd be interesting to hear this antenna singing during a wind storm. Eight whistles :p,.. so maybe some thoughts on closing the ends of the tubes should be considered. Would simply squishing the ends closed effect the performance?
 

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Because of the use of 1 inch tubing with 14 ga phasing lines, the NEC program engine is kicking out a lot of Errors and Warnings about that large disparity in sizes. Also, in order to adjust AGT, I had to use a segment size of 5, which decreases accuracy. So I would say the gain figures are probably overstated. However, the relative trend shown is useful.



As is, the antenna is peaking at 812 mhz. Channel 51 goes up to only 698 mhz and channel 69 only went up to 806 mhz. Without a reflector, the peak is at 830 mhz. So it does show that the tubes need to be longer. 9 inches would have the antenna peak at 698 mhz, and the bay spacing would also have to be increased. Also the short reflector to driven element distance is increasing the SWR significantly.

NEC file:

Code:
CM Bovals 1inch Fat Dipole 4 bay
CM AGT = 1.0 (0db) at 585mhz, Autoseg = 5
CM Lots of NEC Errors and Warnings due to 1 inch dipole and 14 ga phasing lines
CE
GW	24	1	2.875	-0.875	10.5	2.875	-0.875	9	0.0321
GW	25	1	2.875	0.875	10.5	2.875	0.875	9	0.0321
GW	26	3	2.875	-0.875	7	2.875	-0.875	3.5	0.0321
GW	27	3	2.875	0.875	7	2.875	0.875	3.5	0.0321
GW	28	1	2.875	0.875	7	3.275	1.0927e-15	8	0.0321
GW	29	1	2.875	-0.875	9	3.275	1.0927e-15	8	0.0321
GW	30	1	2.875	-0.875	7	2.475	1.0927e-15	8	0.0321
GW	31	1	2.875	0.875	9	2.475	1.0927e-15	8	0.0321
GW	32	1	2.875	-0.875	-10.5	2.875	-0.875	-9	0.0321
GW	33	1	2.875	0.875	-10.5	2.875	0.875	-9	0.0321
GW	34	3	2.875	-0.875	-7	2.875	-0.875	-3.5	0.0321
GW	35	3	2.875	0.875	-7	2.875	0.875	-3.5	0.0321
GW	36	1	2.875	0.875	-7	3.275	1.0927e-15	-8	0.0321
GW	37	1	2.875	-0.875	-9	3.275	1.0927e-15	-8	0.0321
GW	38	1	2.875	-0.875	-7	2.475	1.0927e-15	-8	0.0321
GW	39	1	2.875	0.875	-9	2.475	1.0927e-15	-8	0.0321
GW	40	3	2.875	-0.875	3.5	2.875	-0.875	0	0.0321
GW	41	3	2.875	0.875	3.5	2.875	0.875	0	0.0321
GW	42	3	2.875	-0.875	-3.5	2.875	-0.875	0	0.0321
GW	43	3	2.875	0.875	-3.5	2.875	0.875	0	0.0321
GW	813	1	2.875	-0.875	0	2.875	0.875	0	0.475
GW	814	3	2.875	0.875	10.5	2.875	7.875	10.5	0.5
GW	815	3	2.875	-0.875	-3.5	2.875	-7.875	-3.5	0.5
GW	816	3	2.875	0.875	3.5	2.875	7.875	3.5	0.5
GW	817	3	2.875	-0.875	3.5	2.875	-7.875	3.5	0.5
GW	818	3	2.875	0.875	-3.5	2.875	7.875	-3.5	0.5
GW	819	3	2.875	-0.875	10.5	2.875	-7.875	10.5	0.5
GW	820	3	2.875	-0.875	-10.5	2.875	-7.875	-10.5	0.5
GW	821	3	2.875	0.875	-10.5	2.875	7.875	-10.5	0.5
GW	822	11	0	-10	0	0	10	0	0.1875
GW	823	11	0	-10	1.875	0	10	1.875	0.125
GW	824	11	0	-10	3.75	0	10	3.75	0.125
GW	825	11	0	-10	5.625	0	10	5.625	0.125
GW	826	11	0	-10	7.5	0	10	7.5	0.125
GW	827	11	0	-10	9.375	0	10	9.375	0.125
GW	828	11	0	-10	11.25	0	10	11.25	0.125
GW	829	11	0	-10	13.125	0	10	13.125	0.125
GW	830	11	0	-10	15	0	10	15	0.125
GW	831	11	0	-10	16.875	0	10	16.875	0.1875
GW	832	11	0	-9.975	-16.875	0	10.025	-16.875	0.1875
GW	833	11	0	-9.975	-15	0	10.025	-15	0.125
GW	834	11	0	-9.975	-13.125	0	10.025	-13.125	0.125
GW	835	11	0	-9.975	-11.25	0	10.025	-11.25	0.125
GW	836	11	0	-9.975	-9.375	0	10.025	-9.375	0.125
GW	837	11	0	-9.975	-7.5	0	10.025	-7.5	0.125
GW	838	11	0	-9.975	-5.625	0	10.025	-5.625	0.125
GW	839	11	0	-9.975	-3.75	0	10.025	-3.75	0.125
GW	840	11	0	-9.975	-1.875	0	10.025	-1.875	0.125
GS	0	0	0.0254		' All in in.
GE	0
EK
LD	5	0	0	0	1.66667e7	0
EX	0	813	1	0	1	0
GN	-1
FR	0	1	0	0	585	0
 

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Discussion Starter #19
Chubby 4 bay w/narods

I'd like to give it a try, so I have 2 lengths of 29.5" AL tube 7/8" O.D. I can cut them to 29"

Those tubes being that big, should I put them farther than half an inch from the top and bottom elements ?

Thank you 300ohm for the modeling, but I don't believe in going longer with the elements. One thing that I'll try though is increasing the ref/ele spacing by an extra 2 inches.
.
 

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Those tubes being that big, should I put them farther than half an inch from the top and bottom elements ?
Probably yes, Ill have to model it later. I wouldn't cut the tubes, at least not yet, that .5 inch difference wont shift the vhf-hi frequency much.
 
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