N78 Antenna

[Alumni 0]

On 3/20/2025 at 0:43 PM, papagayor said:

Thanks, I've seen this construction, looking for a way to reduce frequency to 3300-3800MHz. Ca it be modified? I want to attach it on a 60cm parabolic disk.

To shift the operating frequency upwards, you'll need to scale down the entire antenna geometry proportionally, since resonant frequency is inversely related to physical size. For your band:

The center frequency shifts from ~2.2 GHz to ~3.55 GHz, which is ~1.6x higher.

So, reduce all dimensions by a factor of ~1/1.6 ≈ 0.625.

Your material choices (copper sheets/tubes or aluminum with proper mounting) are reasonable. Soldering for copper is perfect; for aluminum, ensure electrical continuity between parts, self-tapping screws or conductive paste with bolts can work

[papagayor 8]

Without simulating the antenna is difficult for me, because as I've seen by seeking online, when an element size change the whole antenna elements must be change, because not only elements size is critical but also distance and position on reflector is critical too. I liked the Kathrein antennas procedure as they are very simple, and trying to make something similar by 4 copper sheet dipoles soldered on copper tubes and then solder tubes on reflector. Also I saw somewhere a Kathrein dipole antenna, that was like an upside down Π, that was a simple idea but cannot make the calculations.

All I need is to make and mount a 3300-3800MHz antenna on a parabolic dish

Edited April 23 by papagayor

[Admin 2683]

papagayor...see this 

",,,such an antenna can be calculated for the 3300-3800 MHz band"

[papagayor 8]

Calculations are not my best, so asking ChatGPT and DeepSeek for help by giving some dimensions and ask them to calculate frequency, or opposite, until I find a simple but good solution

[Admin 2683]

ChatGPT  or DeepSeek will never be able to solve your problems in a real way...it's fake"

[papagayor 8]

Then I have no luck, only by continue seeking online for some plans

 

[Admin 2683]

I think I'll make you a good antenna for the desired frequency."

[papagayor 8]

Thank you very much sir, but please can't my drawings be modified to work in this area? Because they're easy to be made for my skills. Also a dual polarized batwing with two ports would interesting.

[papagayor 8]

Or like this one

[papagayor 8]

Also I made a dual biquad, based on online calculations, and even I cannot test it for performance, my speedtests increased very much, i was taking -test in the morning when no much clients in ISP antenna- 30-50 Mbps and now it go up to 60-80 and some times over 150. I can't understand too much about measures, but looking in router results I took the attached measures, the SINR is not always the same it goes up-down to 1-10/

DBQuad.pdf

Edited April 24 by papagayor

[Admin 2683]

1 hour ago, papagayor said:

Or like this one

I will design you such an antenna for the desired frequency....!!!

[Admin 2683]

,,,this is for you...(Why isn't you forget to see about Messages(up)

 

3300-3800 MHz BESTER.cst

[papagayor 8]

THANK YOU VERY MUCH!!!!!! Now please can I add a second port in 45 degrees phase to existing one, or need mods?

[Admin 2683]

,,,not 45 degrees,120 degrees...!!!

[papagayor 8]

???

[Admin 2683]

YES,,,the second port is at 120 degrees...!!!

[papagayor 8]

Some explains please sir, all elements tube and disks can be copper made, and should be touch each other (electrically connected)? Also does the thickness of disks matter, thinking about using 0,5mm copper???

[Admin 2683]

,,,the material doesn't matter...the main thing is that it can be welded...!!!
,,,for your frequency range a smaller thickness is preferable...!!
,,,all the antenna elements are electrically connected...!!!

[papagayor 8]

PERFECT, I'm going on construction

[papagayor 8]

Good morning, forgot to ask something, what if tube is a bit different like 6 or 8mm instead of 7, because 7 is a difficult dia and cannot find it easily

[Admin 2683]

,,,choose the tube with 6 mm diameter...!!!

[papagayor 8]

The file you send me before is not correct and need to be modified in red line points as follow:
1. At these points the tubes are soldered on Reflector.
2. Tubes have the same length with the other 2 opposite tubes.
3. Under these 2 tubes, 2 SMA or N-type ports will be soldered.
So I send you back the .cst file, I changed the dipoles size, but
cannot modify tubes length and holes so that tubes electrically
connected on reflector.
If you have some time modify it and maybe new drawing be better, or mod it for 3.5GHz, it's very easy to be constructed.

 

3.52-1ghz.cst

[Admin 2683]

,,,you know how to work with cst-studio...???

[papagayor 8]

Trying to learn

[Admin 2683]

,,,see it...!!!