Parabolic antenna 2.4 GHz

[Pupe 7]

Good afternoon, I'm trying to make an antenna for 2.4. the emitter shows good parameters, but when I put the mirror on, the parameters float away a lot. I set the calculation to parmetrezation in order to change the focal length. What could be the reason for such results? can you suggest literature/articles on how to design a mirror? when calculating, I used the formulas that I attach.

[Pupe 7]

the polyimide case does not wag, calculations were made with it and without it, it did not play a role

 

[Admin 2578]

 I think it must be f/D=0,6

Did you get the antenna from this forum...????

What is the diameter of the parabola...???

[Pupe 7]

yes, I took the antenna in your image and likeness and slightly adjusted it to the 2.4 range. the mirror diameter is 780 mm, the required gain is 25 dB, f=350 mm, the parabola equation is x^2= 1.404*y

[Admin 2578]

,,,but f/D=0.,448 ,it must to be 0,6...!!!

[Pupe 7]

I am thinking about changing the position of the antenna along such a trajectory, but I did not find information on which arc to move along

[Pupe 7]

7 minutes ago, Admin said:

,,,but f/D=0.,448 ,it must to be 0,6...!!!

Okay, thanks, I'll try to count it now!

[Pupe 7]

9 minutes ago, Admin said:

,,,but f/D=0.,448 ,it must to be 0,6...!!!

Does this rule apply to all parabolic antennas?  And another question is about the efficiency coefficient and the utilization coefficient of the surface of the parabola. I chose both of these values for 0.9, but perhaps they should be changed... how are these parameters normalized?

[Admin 2578]

No, this is not a general rule....what do you mean by efficiency coefficient...!!!...???

[Pupe 7]

antenna effeciency 

[Admin 2578]

0.01 dB

[Admin 2578]

,,,this is the simulation with your parabola(f/D=0,6)...

and Efficiencies...

And this is the antenna...

[Pupe 7]

I'm probably using the wrong formulas... the shape of the mirrors in your project and mine are very different. here is my calculation. the Kp value was 0.83 and 0.6 (surface utilization factor)

25dBi_2400MHz.cst

[Pupe 7]

of course there are flaws, the f parameter does not accurately display the distance between the antenna and the mirror, but I think that's not the problem with my poor results

 

[Admin 2578]

,,,take this...

parabola0,6.cst

[Pupe 7]

Yes, that was a mistake... I was multiplying the coefficient and I had to divide it)

[clanon 258]

The shape of the main LOBE IIRC at -6 db affects efficiency...

 

[clanon 258]

I think he means -6 db lobe pattern guarantees good efficiency for shallow dishes (with -4 loss at the border)

Edited November 24 by clanon

[clanon 258]

10 db is when losses are at minimum for both Spillover and illumination...

Edited November 24 by clanon

[Admin 2578]

,,,read this..https://www.antenna-theory.com/antennas/reflectors/dish3.php#:~:text=Aperture Taper Efficiency&text=This efficiency can be improved,the spillover efficiency%2C discussed next.

[Admin 2578]

,,,f/D=0.25...you can see the difference...!!!