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Antonius

Catherine antenna

55 posts in this topic

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.

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

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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.

image_31690.png

Edited by Harry36
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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.

tmp-cam-7885600490158515936.jpg

tmp-cam-8318565331446372002.jpg

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tmp-cam-1282207880387534431.jpg

tmp-cam-2614000541556298711.jpg

tmp-cam-3086528052692711081.jpg

tmp-cam-1030659425933383618.jpg

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

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Admin,I don't understand what you mean.

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

 

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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.

 

tmp-cam-18587475777611885.jpg

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

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tmp-cam-8174757563326704163.jpgOn marketplace online platform

In Indonesia like shopee,lazada,bukalapak,and tokopedia

The seller get it from "flea market"tmp-cam-766346691459643408.jpg

tmp-cam-2907823111363092398.jpg

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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.

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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

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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?

VideoCapture_20211213-165005.jpg

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

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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

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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 %

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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:

tmp-cam-8318565331446372002.jpg

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 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)

 

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Gregorian Antenna – symmetrical reflector...

gregorian_image002_0000.jpg

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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

33-997-212-04.jpg

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Thanks for advice.

I'll try someday.

Edited by Shabra
Emoticon symbol may be give missinterpretation.
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On 12/12/2021 at 4:56 PM, Admin said:

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

tmp-cam-5786940898015854984.jpgThe result is better than ever.

 

 

Edited by Shabra
Double pictures.

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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...

a08526d431ce2271458d7ed16fbdcd6c.thumb.jpg

PS-100-Structural-Aluminum-Extrusion-Profile-Dimensions.jpg

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IMHO for lte1700-2700 very nice

52fbcb8bf07aadcd162b450389ae2032.jpg

068906521d8ca695f4d08de4e3988fb4.jpg

Edited by Harry36

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

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

 

 

IMG_20220524_120928_893.png

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