Slot Dipol AKA Sputnik Lite

[Dr. Pepper 58]

Harry36 provided a slot dipole as an antenna for drones:

I designed a similar antenna for 1.7 to 2.7 GHz which gives a good gain and low swr over the communication band. Somewhere here or on Lan23 i see a picture of something similar with slots at the end so i also used them. For everyone who wants to recalculate such an antenna you will find the cst file below. I think for its simplicity it performs very well. 

 

Size:

Spoiler

 

CST

slot antenna max band.cst

[Admin 2545]

,,, is a copy of Petra20...

 

[Dr. Pepper 58]

Yes this was the picture i have in mind. Thanks for the hint

[Dr. Pepper 58]

An improved version of the slot dipole with wings. Good broadband behavior and good gain.  1.7 - 2.7 GHz with SWR <1.3, Gain from 2.1 - 2.5 GHz > 13 dBi

[Dr. Pepper 58]

And additional a variant with directors. They harmonize good with the design but they give only a slight improvement.

[didy 0]

Hello Can you please put the dimensions in lambda so that it is easy to build for other frequencies as well? In fact, this request would be general on the forum. Maybe the admin will stick it.

Thanks

[Admin 2545]

,,, it is possible, but a medium (center) frequency must be chosen...!!!

[Dr. Pepper 58]

then its necessary to analyze the structure and look which parameter is related to lamda and which is perhaps related to other factors. And yes you have to find a center frequency. For a single band antenna this is easy for such a multiband its much trial and error i think. For me its easier to re-optimize the design for another frequency range. For lower frequency's there should be better designs that are not so big, the only other range i can imagine is in the 5GHz region but there you not need such a wide bandwith. 

 

Attached you will find the cst file, feel free to recalculate it for another freq. range or to find the lambda depending parameters ;-)

slot antenna 17-27-reflectors.cst

[Admin 2545]

,,,it is still possible...!!!

slot patch.cst

[Dr. Pepper 58]

You are a real master 

[Dr. Pepper 58]

The slot dipole with V cut outs like an batwing antenna, not as good for broadband application but a little more compact than the slot dipole and a good gainer. Here an example for a wifi antenna

slot antenna with V 24-25.cst

[Harry36 140]

19 hours ago, Dr. Pepper said:

The slot dipole with V cut outs like an batwing antenna, not as good for broadband application but a little more compact than the slot dipole and a good gainer. Here an example for a wifi antenna

Try to draw a balancing device in the model.

[Dr. Pepper 58]

I found some motivation and tried to add a balun to the design to see if this works and with some calculation i found a solution:

Side view (without legs to get a chance to look inside):

 

woks quite good, good broadband behavior and a good gain of 14.6 dBi. Its a bit like a batwing antenna 

[Harry36 140]

12 hours ago, Dr. Pepper said:

I found some motivation and tried to add a balun to the design to see if this works and with some calculation i found a solution:

Side view (without legs to get a chance to look inside):

 

woks quite good, good broadband behavior and a good gain of 14.6 dBi. Its a bit like a batwing antenna 

A good start! It remains to choose the sizes to expand the band 1700-2700. Once you do, I’ll give you another good idea.

[Dr. Pepper 58]

I found a configuration (sides invisible to see the balun) with a wider band but its not much better than the earlier design without the v-cuts on July 2022, good in the old design there is no balun used but I think this should also work with a balun. Only benefit is perhaps the more compact size. But compared to a batwing antenna the gain is slightly better. I think for the cost of a few 0.x dBi the swr could even be lower. When made in 2 pieces it should also be easy to produce this antenna even without expensive tools.

 

[Dr. Pepper 58]

Another variant of this antenna. This time optimized for 3D Printing. The base is calculated as a 1.4mm Sheet PETG covered with copper foil on both sides. This is not as ideal as a full sheet of metal but it can be easy produced even without tools. Its also constructed with a balun which is connected to both sides and sma port. Its quite impressive how broadband such an antenna can be and it gives a max. gain of 13.5 dBi at 2.1 GHz. With the big cut out it goes even more in the direction of a batwing antenna.

 

[Admin 2545]

,,,some drawings if possible...!!!

[Dr. Pepper 58]

I can post the dimensions when im back home or tomorrow, but i will also try a only metal variant. This should even be better

 

[Dr. Pepper 58]

So here i try to give the dimensions, its not so easy to pick always the right points so dimensions can be off a few µm because of the many layers. I have to add a metal layer of 0.5mm on the sides otherwise the solver produces errors because of the to big mesh size wich results in crashes after a few calculations. So i made the metal layer a little bit bigger. This has later to be considered when printing the inner part (PETG, epsilon 2.6).

Dimensions:

Spoiler

 on the second picture the distance is 1.92mm ;-)

I will try what happens when the design is all metal, should be better. The polymer layer is not beneficial 

 

Here also my messy (because of many trial and error) cst file 

slot antenna with V 17-27-balun-3d.cst

[Dr. Pepper 58]

I crunched the numbers for the all metal antenna (0.5mm thick) and the result is better, but see by yourself (I made the reflector invisible for better view):

Good gain and a very wide resonance, usable from 1.5 to 3.2 GHz if needed. With this wide band its not avoidable to have this bad swr from 1.6 to 2.3 GHz, I was not able to find a solution where everything is on swr 1.2 or lower. I think for this the antenna has to be recalculated for a more narrower resonance. Its interesting that the peak Gain is still 13.5 dBi, seems to be very stable on this design