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aurel

BatWing antenna 2.4 ghz

304 posts in this topic

I also thought about such a design like a fractal antenna to increase bandwidth and perhaps gain but i don't know if you can reduce the distance so much that two batwings are touching.  I found a paper about stacked batwings but this is a little different.

stacked butwing.pdf

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A new experiment with a 3d printed batwing + Copper tape. This time with a carefully optimized design for good swr. Ive got a very good swr right on the spot without any adjustment of the antenna and the signal strengt of a 5ghz signal improves also a lot compared to a rubber duck antenna (~50% to ~70%). Unfortunately the gain drops a little with this design but at least it works good enough. This is the compromise you have to go when trying to use a dual band antenna. The RG316 is about 20cm long, so the measured swr shows a little to low values, but somehow you have to bring the signal to the antenna ;). Attached some information about the design. 

Measured SWR of 1.02 :D and picture:

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swr.jpg  photo.jpg

Dimensions:

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front.png bottom.png

Wave plots for 2.4 and 5.2 GHz:

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gain 2-4.png gain 5-2.png

Gain over Frequency plot:

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gain vs freq.png

SWR Curve + Impedance plot:

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swr-calc.png impedance.png

 

 

batwing dual band-3d-2.cst

dual band batwing.stl

swr-measured.jpg

Edited by Dr. Pepper
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Update about the 3D Batwing. I had to optimize the reflector also. Now the antenna gives also proper gain in the 5.2 GHz range as in the 2.4 GHz range. Attached the new dimensions and Results. Please keep in mind, this only works when 3d printed. A bare metal antenna will have other dimensions!

Dimensions:

Spoiler

front.pngside.png

Gain:

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gain over freq.png gain 244.png

SWR + Impedance:

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VSWR.pngImpedance.png

 

VSWR.png

Dual Band Batwing.stl

Edited by Dr. Pepper
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I played around combining batwings together, look what happen when you combine 3 batwings, easy 15.5 dBi (only calculated to fit 2.44 GHz but can be also very broadband):

Gain.png swr.png

 

Also interesting when you combine this bad boy with a second one into an 2 X 1 array (18 dBi):

2 array.png

Impedance and size:

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Impedance.pngsize1.pngsize2.png height = 23.7mm

When 15dbi is also ok the size of the reflector can be smaller. To squeeze out the last bit of gain cst calculated a bigger reflector. It is still calculated without any support to hold it up but i think the design has potential ;-).

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I have recalculated Admins 5 Ghz batwing (Page 8) for better SWR if somebody want to make one. I also found that the SWR could be improved if the leg is not touching the reflector, so i added a hole at this place to reduce contact which seems to work. From the calculations the antenna should perform and work very well:

 

Gain:

Spoiler

gain 5-5.png gain over freq.png

VSWR + S11:

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VSWR.png S1,1.png

 Dimensions (this thing is tiny :D):

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3D-2.png 3D-1.png 

I forget to mark the round hole at the end of the slit, its 2.2

Impedance:

Spoiler

Impedance.png

 

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Additional a scan over a wider freq range to look how broadband the antenna is, and yes its very broadband. Usable from 4.15 GHz to 6.8 GHz:

VSWR-bb.png

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And another variant of Batwing antenna, this time optimized for maximal gain and only one small frequency region (2.4G Wifi). With this restriction you can realize 13dB gain with this antenna. 

So the Batwing design is very flexible, can be brought band, small band, dual band, 3D printed, gives high gain and is relative easy to manufacture.

 

batwing max gain-endcalc_02.gif

 

Gain:

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3D Gain.png Gain Curve.png

S11 + VSWR:

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S11.png vswr.png

Impedance:

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Impedance.png

Dimensions:

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length1.pnglength2.png

 

batwing max gain-endcalc.cst

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With the help of Harry36 and this post: https://www.lan23.ru/forum/node/321323 i changed the design of the maximum gain Batwing with directors and got a real good result by using 10mm tubes as a director. The gain can be up to 15dBi but then the bandwidth is limited. I choose a more robust option that even crocked hands will have a good result with this. When i have time i will try to make one of these. The holder for the tubes can be 3D printed and the rest is a simple batwing so not to hard to make. The footprint of this antenna is only 20cmx20cm so its not so big like a horn antenna or like the "wifi gun" designs which look cool but have limited bandwidth and are very long.

overwiew2.png

batwing max gain with directors.cst

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great job!

there's still some tuning left :)

in the region of 2 GHz there is a break in the SWR graph. change the dimensions of the directors (diameter and height above the batwing, it is not necessary to do everything at the same height) and you should get a broadband antenna like I have on Lan23 :)

Making a narrowband antenna is not so difficult, but stretching the bandwidth to the maximum is much more interesting :)

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make directors from a core of a copper cable for electrical wiring (see the typical diameter from the wire section). The directors holder can be made from a thin strip cut from galvanized steel, like the butwing itself, the directors can be soldered onto the holder simply and quickly. you can fix the holder to the "batwing" racks with rivets.

and I would slightly increase the size of the antenna so that the maximum gain falls on the desired frequency (2.45) or to capture the entire band 1700-2700 in SW<2...1.5.

the size of the antenna (more precisely, the reflector) will directly determine the gain :)

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"Making a narrowband antenna is not so difficult, but stretching the bandwidth to the maximum is much more interesting"

Its always depending on the goal :D, you can have a narrow band with high gain or wide bandwidth with lower gain, i see both on my trials calculating the parameters. My goal this time was to get good gain only on the 2.4GHz Wifi band with a compromise about the two scenarios, but i will also make a version with maximal bandwidth like the original batwing.

"make directors from a core of a copper cable for electrical wiring"

I first calculated the design with solid rods and i see no difference by using tubes. In theory the big tubes should have a higher bandwidth like a thinner wire but i will try it out.

"The directors holder can be made from a thin strip cut from galvanized steel, like the butwing itself, the directors can be soldered onto the holder simply and quickly"

The idea is good, but i have no laser cutter to make everything out of steel sheets, my fist batwing was made of this cut with scissors which was terrible. So i changed to aluminium which is easier to work with. To solder on it i apply a patch of copper tape which works very well. For the director holder its more easy for me to print this part with my Ender 3, then all the dimensions are right and i have to simply press start B|. For the batwing itself i also showed that this works but sheet metal gives here more gain and better swr. Copper tape and 3D-Printed part are only a poor mans replacement for printed circuit board which has losses like the original ones. 

 

But the idea with the rivets is good, my fist plan was to print some holes in the structure of the holder and use screws from behind the reflector to hold it in place. But perhaps even a cable tie will work here. But first lets modify the design a little.

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,,,the best Batwing....

screenshot_1255.jpg

 

screenshot_1256.jpg

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I made a Batwing with directors and the swr is quite good. I have to make an mount for a tripod than i will compare it to some antennas but not today ;-). The result is a little bit different to the calculation but everything is made by hand so not 100% correct. In the middle of the wifi band the swr is at 1.1 to 1.15 depending where the antenna is pointed to. Its interesting that the antenna is still usable from 1.9 to 2.9 GHz so if the range from 1.7 to 2.7 GHz is needed it could be recalculated for 2.2 GHz and would still have a good gain. As i mentioned before i used Aluminium tubes for the directors which works quite well and printed the holder with PETG. The rest is also Aluminium sheet (0.5mm) cut with a wallpaper knife for clean cuts and soldered on with the help of copper tape. 

Batwing with directors.jpg swr.jpg

Edited by Dr. Pepper

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,,, it is possible, but you do not get the same gain...!!!!

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,,, you can bend the galvanized sheet like this ...

screenshot_1298.jpg

,,,or like this...

screenshot_1299.jpg

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I managed to optimize the Batwing antenna by using an elliptical curve, which led to a uniformity of broadband...

screenshot_1347.jpg

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17 minutes ago, Hamza said:

good job

,,,thanks...!!!

,,, soon I will give the dimensions ... !!!

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