Dr. Pepper

If somebody is interested in this you can find a model on thingiverse but its important how you attach this yagi on the router antenna. It influences the swr strongly. I found it works best at the start or end of the antenna like in the pictures and worst in the middle. Best is to try some positions from top to down and look on the signal strength on the receiving end.

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 and picture: Dimensions: Wave plots for 2.4 and 5.2 GHz: Gain over Frequency plot: SWR Curve + Impedance plot: batwing dual band-3d-2.cst dual band batwing.stl

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

Sounds like a plan, but give me some time to better understand what im doing ;-) i use the program for one day right now.

I use a relative new laptop called Legion 5 with i7-10750H (6 cores, 12 threads) and an RTX-2060 as graphics card. Would be nice to use more of the cpu power. When cst runs on cpu mode for some tasks it only uses ~40% of the cpu but when it uses the gpu the cuda cores are used to about 90%, then this task is done very fast. When only the cpu is used it takes some time for calculation. Most of the time the Laptop is in idle mode, it can use its power to calculate new dimensions in this time. But i already reduced the parameters of interest to the reasonable ones (max. 3-4) and i also reduce the max. number of evaluations to 20-100 and also the domain accuracy to 0.5 to speed things up when running the optimization. Later on i test again with a higher accuracy and more evaluations but the result didn't change that much.

Still learning, but its not so complicated with the help in this forum and some yt videos. Thankfully i get my graphics card running on the optimizer so i have not to wait too long for a result. But i have to play around with the settings a little more.

First time i tried to work with cst and optimize an antenna. I wanted to modify the batwing to work as a dual band antenna for 2.4GHz and 5Ghz Wifi like Admin did on Page 8 but only with the newer design. I used the batwing simply design provided by admin which was easyer than to try to design my own one, this will com later after more learning. When it works like that it should be ok for a dual band antenna: Gain plots Gain Curve SWR Curve : batwing dual band.cst

I found out why the swr was so high with the printed batwing antenna. I had simply to add more solder to the copper layer to change the capacitance between the gap. Reducing the amount of polymer also improves things so that the swr gets into the range of~1.25. I also made one out of aluminium sheet which works best so far. I had only to minor adjust the gap to tune the antenna to the desired level to overcome the handmade errors on cutting the shape out of the sheet. Look at the beautiful swr curve. Its also a nice trick to solder on aluminium sheet, simply use a patch of copper tape on top.

You not only have to consider conductivity also price, stability and weather resistivity. For performance copper or even silver would be the best for all parts of the antenna, for price and mechanical stability zinc coated steel would be the best. This should also withstand weather for a relative long period. Would be interesting to cover the steel sheets with copper in a galvanic process. Aluminium can also be used but is hard to solder on.

A small update about the 3D printed batwing. I made one with printed reflector which works very good. I also made one with 0.5mm aluminium sheet as reflector which gives even more gain. The problem was only that on the aluminium one i have to reduce the distance to the reflector to ~25mm to get a good SWR. With the original 35mm the SWR was only 2.1, with 25mm it improves to 1.3 @ 2440 MHz. Can be the extra PETG to make the antenna more sturdy or that i used a 200mm wide sheet as reflector and not the recommended 130mm one. I have to learn CST studio to do some optimizations when copper tape and a printed body is used. I also use now RG316 cable which is much better in routing and easyer to solder. The Airborne 5 i used earlier has lower losses but is so stiff that is nearly impossible to route like this.

You are right, i rooted the wire like in your picture and the swr improves a lot to 1.14 @ 2445MHz. But i have to design my model more rigid, the 5mm coax is so stiff that it bends the antenna and it wont stay in place. Will be implemented in the next generation. But its surprising that even with copper tape the antenna performs that good, no need for expensive tools.

I performed a little gain test with a wifi network nearby behind some walls as a target with two commercial antennas for comparison. Even the 3d printed version with pcb reflector outperforms the tl-2409 antenna which is claimed 9dbi. The batwing is really a good performer. Thanks again for all the optimization work on this antenna.

First prototype of a 3d printed batwing antenna + copper tape. It works but have to be optimized, the sheet one is better, but its much easier to make. 1mm PETG as substrate.

Thank you for all your work on optimizing the batwing antenna. I finished today my first one (page 2 in the middle) with a great SWR and good bandwidth. The SWR is indeed better when the coax is parallel to the antenna. I compared the performance with a TL-ANT2409A and both show nearly the same signal intensity even with my rough built. Next i will play a little bit around with the combination of 3d-printing and copper tape, even when the permittivity is different it should be much easier than cutting steel sheets without power tools.