Offset Antenna 2.4 Ghz

[Vondertrenk]

A friend of mine told me he was given this antenna for free and wants to know what he can do on C-Band. What is his best option? What does he needs to receive C-Band? Also what are the options for KU and what does he needs?

The antenna seems to have been used for data transmission.

 

[KE4EST]

Do you have a picture of the front of it? Do you know the size?

 

[primestar31]

That's a offset Prodelin dish. Maybe even a 6-footer, which is a good start for anybody! Yes, it'll do C-band, though it's made for KU

There are MANY threads for people here that have these dishes. You shouldn't have any issues finding them. Just try searching on " Prodelin " as a search term.

 

[DJdish]

There are some recent threads on folks getting started on Ku, which may provide you with some interesting info.
As mentioned above that dish can be used for Ku, and even for some C-band use.

 

[Vondertrenk]

It is actually a 2.4 mts dish, I have been flying RC planes recently and they use the new Spectrum 2.4 Ghz band transmitter. This shall be the reason why I entitled this thread as Offset Antenna "2.4GHZ" instead of 2.4 mts. Sorry for the mistake.
Are you guys sure this is a Prodelin offset dish? There was no label with any type of brand or model, just the attached picture showing the size (2.4 mt reflector). If that is the case, he might be able to go with any C-Band LNB with the conical scalar ring. (I will recommend him the Titanium PLL C2)
The modem is EF DATA model RFT-505 that TX/RX in 4 and 5 GHz.
This is a fibreglass antenna. See additional pictures.

 

[primestar31]

It absolutely is a Prodelin dish. The mount is a dead giveaway.

 

[scarecrovv]

Just like mine. 2.4 meter. Removed the transmitter lnb jobby and put combination c and ku band on it , pointed at 99w and bobs your uncle. Had to bend the back piece that held the old lnb. Sorry can't post picture....usb shagged up on this computer. Dish is a heavy sob you will need help. Put mine up myself and it damn near killed me.
"If that is the case, he might be able to go with any C-Band LNB with the conical scalar ring." Yeah I use a conical scalar on mine.

 

[FaT Air]

Is that 'thing' in Central America? It's an offset dish but at that angle it's looking like straight up.
Commercial 2.4 meter should work pretty well on C band.

 

[Vondertrenk]

Is that 'thing' in Central America? It's an offset dish but at that angle it's looking like straight up.
Commercial 2.4 meter should work pretty well on C band.

Close. I am going to visit him on vacations and he has asked me to help him with it. The guys has a cottage where not even the eagles dare and no local TV at all ( the hills block it).
This dish might be the solution, even if not for local, at least for some type of entertainment. I will be flying this evening and wanted to make sure I am brining the right stuff, however I dont have a good C-Ku band LNB, that would be possible to do the C-band LNB on the mount and another Ku aside?

 

[KE4EST]

Yes with an offset dish like that you can mount a Ku as a side car.

 

[Vondertrenk]

Yes with an offset dish like that you can mount Ku as a side car.

What the #@$##$*#!, You are right! People do that all the time, they even add a front bar with up to 10 LNBs!

I guess since I am running out of time am getting a little bit confused, I will be flying this evening and need to buy whatever is required to do the job; I did it myself with my 6 ft dish, see attached pictures; 1 Titanium PLL C1 for C Band circular and one BSC-621 for linear C and Ku. And all of them work perfectly..

Now I have to take a while and find out what is out there available in the caribbean and the best bird to shoot at with the dish, I guess browsing Lyngsat and footprints will give me a better idea

 

[FaT Air]

99W, most 'good stuff' is Horizontal Polarity. So maybe with the existing LNB/feed 'set' appropriately?

 

[scarecrovv]

Don't forget the offset angle of 22.3 on that dish so you will have to point it 22.3 degrees lower than a prime focus to pick up your sat.

 

[migold]

99W carries programming for the Virgin Islands, should be available in most of the Caribbean. My avatar shows 2.4 meter prime focus with main LNBF for 99W and offset for 105W.

 

[Vondertrenk]

Don't forget the offset angle of 22.3 on that dish so you will have to point it 22.3 degrees lower than a prime focus to pick up your sat.

Hi Scarecrovv.
Do you know if the angle found with Dishpointer is just for prime focus? So if the dishpointer result is for example 42.3 deg means the real angle for this dish is 20 deg?

 

[Titanium]

Your calculation is probably very close.

Offset dishes are looking at a point higher in the sky than what the reflector is pointed at. This is because the offset design places the feedhorn below the center of the dish.

DishPointer is like all satellite position calculators and provides the actual elevation angle for the satellite. If aiming an offset dish that has a scale on the mount, set to this same angle. If the offset dish does not have an elevation scale on the mount, you must know the offset angle of the dish to subtract from the satellite angle for calculating the reflector's angle measured on the face. The angle finder can then be placed on the vertical plane of the reflector to aim at the satellite position.

Satellite Elevation Angle - Dish Offset Angle = Actual Dish Angle (measured from the top edge to bottom edge).

 

[scarecrovv]

Your calculation is probably very close.

Offset dishes are looking at a point higher in the sky than what the reflector is pointed at. This is because the offset design places the feedhorn below the center of the dish.

DishPointer is like all satellite position calculators and provides the actual elevation angle for the satellite. If aiming an offset dish that has a scale on the mount, set to this same angle. If the offset dish does not have an elevation scale on the mount, you must know the offset angle of the dish to subtract from the satellite angle for calculating the reflector's angle measured on the face. The angle finder can then be placed on the vertical plane of the reflector to aim at the satellite position.

Satellite Elevation Angle - Dish Offset Angle = Actual Dish Angle (measured from the top edge to bottom edge).

What he said

 

[Vondertrenk]

You are right Brian. The offset dish (most of them) already define the the elevation scale on the bracket. That's my friend Franco changing the LNB to test the antenna performance before moving it to his country house. We shall be testing it either tomorrow or during the weekend.