Catherine antenna

[Shabra 23]

Focus point grid antenna (60 x 90)cm is 31.25 cm

Yes I have did it(reflector antenna vertical) and got more little result.

Oneday I'll take photo of the detail.

[Admin 2545]

,, the secondary reflector from the grid antenna is for either vertical or horizontally  polarization ... you need a secondary reflector with circular polarization...!!!

[Harry36 140]

On 09.12.2021 at 7:37 PM, clanon said:

 

focus point is important (distance to reflector) some mm make a huge difference...

did you try with antenna (reflector ) at 90 degrees...VERTICAL...?

Edited Thursday at 07:38 PM by clanon

 

On screen LTE. -/+45°.

Try it.

Edited December 11, 2021 by Harry36

[Shabra 23]

Focus point grid antenna (60 x 90)cm is 31.25 cm

Yes I have did it(reflector antenna vertical) and got more little result.

Oneday I'll take photo of the detail.

[Admin 2545]

,,,Shabra,try to put the plate in the focus of the parabole grid...!!!

[Shabra 23]

Admin,I don't understand what you mean.

May be you can explain to me something in a picture,please!

 

[Admin 2545]

Do you understand what I mean?

[Shabra 23]

Ok.I'm going to try it at fine weather.Tonight is rainy and little thunder at the sky and decrease the indicator of signal.

 

[Admin 2545]

,,, Shabra,how to get a commercial Kathrein vibrator...???

[Shabra 23]

On marketplace online platform

In Indonesia like shopee,lazada,bukalapak,and tokopedia

The seller get it from "flea market"

[Shabra 23]

Internet service provider that have a BTS(Base transceiver station) have to regenerated the sectoral antenna.If it have reached limit of usage will be changed with the new one antenna.

And maybe someone use part of it(kathrein antenna) to get the signal.

And becomes popular.

[clanon 246]

HUMIDITY and MOISTURE inside COAXIAL cable could be a problem...there. over time. a layer of some insulation or cover all in thin PET (nylon) dielectric paint could be better...

Cable changes inside due to WATER and you lose SIGNAL

[Antonius 17]

For connecting cables from semirigid Teflon cables to 5C 75 ohm tv antenna cables should you use a connector like this or is it better to solder it directly? And how long should the cable be?

[Admin 2545]

,,, it depends on what kind (type) of cable it is ... in any case it is not a 75 ohm impedance cable ... !!!

[clanon 246]

if TOLERANCES (diameters on shield , leads , PCBs) are not maintained , impedance would change. I would solder straight from modem , card to antenna , if possible. Keeping distances as short as possible and impedance (cable shape ,curves) as minimum as possible. ALL connectors have loses imho

[Admin 2545]

Coaxial cables with an impedance of 50 ohms (Ω) are used to connect the transceiver to the antenna. The most common cables are RG 58 and RG 213:The RG 58 cable is used for use, which has a diameter of 5 mm and the losses it introduces are insignificant, due to the small length of the cable. One detail that you MUST keep in mind is that a cable must be equal in length to multiples of ½λ to properly transfer the impedance of the antenna. If the length is different then the cable will work as an impedance transformer. In this case, a properly tuned antenna will have a high SWR at the transceiver output. The shortening factor (k) has a special importance in the calculation of the cable length. It differs depending on the dielectric of the cable.

-shortening factor(k) -Solid Polyethylene (PE):  66 %

[swarg_eu 43]

1. the ground of the antenna needs to be at the defined position to get a proper radiation pattern and impedance matching (mount it on a separate horizontal arm)

On 12. 12. 2021. at 10:44 AM, Shabra said:

 2. the parabolic grid antenna is made for a dipole (you don't use the full reflection area of the grid), you reflect only one part of the polarised wave (-3dB for TX and RX, MIMO is not gonna work in this particular case)

an offset satellite dish is a much better choice for a reflector, kip in mind that there is a polarisation change after a reflection (SISO system limitation)

 

[Admin 2545]

Gregorian Antenna – symmetrical reflector...

[clanon 246]

shabra , what swarg is saying (i think) is that you should MAKE sure that the base of the MED sees a GND (center of grid) at the SAME point like in the BASE station (telecom antenna) which means HOLDING it from OUTSIDE and BEHIND with the circle (director) pointing in to the GRID...

And that the lobe of this MED is FAT and goes in two directions (polarizations) meaning that you are spilling some radiation since your reflector (grid) is almost rectangular (Circular would be better to reflect both dipoles) which are at 90 degrees

[Shabra 23]

Thanks for advice.

I'll try someday.

Edited December 14, 2021 by Shabra
Emoticon symbol may be give missinterpretation.

[Shabra 23]

On 12/12/2021 at 4:56 PM, Admin said:

,,,Shabra,try to put the plate in the focus of the parabole grid...!!!

The result is better than ever.

 

 

Edited December 19, 2021 by Shabra
Double pictures.

[Admin 2545]

On 9/12/2021 at 11:49 PM, Harry36 said:

I've been looking at this for a long time

 

 

,,, maybe this profile would be suitable for this type of antenna...

[Harry36 140]

IMHO for lte1700-2700 very nice

Edited May 24, 2022 by Harry36

[Admin 2545]

Yes, I think you're right, try it.

[Harry36 140]

Structural aluminum dipoles are very expensive to make at home, and can be made even easier with galvanized steel.