Thread: Homemade antennas for KU

Hi..

This should be only for temporary replacement of a dish antenna, testing, or just for fun
All these antennas can be made using homemade materials without much building precision

This is my KU-band Linear polarization antennas collection:

Conical Horn antennas

http://www.satelliteguys.us/fta-shac...ml#post2274046


What is the advantage of using a conical horn antenna? Due to their low noise, a conical horn antenna should have +3dB performance than a dish antenna. But their efficiency is around 50/55%.

I made this antennas with alluminium cardboard, to calculate the sizes i use a freeware called HDL_ANT, just insert the frequency, size of Waveguide (LNB), gain, and hdl_ant will make a template. Just print the template (use Corel Draw to open HDL_ANT generated template)..cut..and mount. A 8 (+-25dBi) inch diameter conical horn it´s enough to receive the strongest TP´s from a 54dBW.

But conical horns get very long with >20inch diameter...

Luneburg spherical lens antennas (my baby Lutenna, which is made with sugar eheh)




http://img14.imageshack.us/img14/4554/semttulogmk.jpg

Based on Farragsat antennas, in smaller versions i can get 130% of efficiency (that´s a lot!!!), but bigger the antenna, smaller the efficiency Original Luneburg theory specifies that the antenna should have several layers with different electric constant materials, this one only have one...sugar (ER=2.0)

It´s multibeam antenna (it´s a ball!), with low noise.

Just get a plastic ball and fill it with sugar. just that simple.

Lens antenna
I dont have here any photos, i can get photos in a few couple of days. But it´s very hard to build one that support both polarization (H and V), but if you want to work only in one polarization it´s very simple to build. I use HDL_ANT to calculate the antenna.

Post any info in other homemade antennas for KU



Sorry for the bad english

parabolic antenna's deliver all the signal IN PHASE and are way more efficient, they are fairly easy to find for free or nearly so

Parabolic as in a normal dish? Ya but those aren't as much fun to experiment with. Although I have wanted to make a pie plate dish for awhile now

Originally Posted by Cadsulfide

parabolic antenna's deliver all the signal IN PHASE and are way more efficient, they are fairly easy to find for free or nearly so

Reflector antennas have poor efficiency, i never saw a parabolic antenna with over 130% of efficiency. I made one spherical antenna using sugar and the antenna had 130% efficiency...how many parabolic antennas can get enough signal to receive the strongest TP´s from a 54dBW with only 100mm of diameter?

Conical horn doesnt get much efficiency, but thanks to low noise..it gives a extra 3dB (3dB is plus 50% of diamter of a parabolic with same efficiency)..a 200mm diameter conical horn, will work like a 300mm parabolic dish.

Originally Posted by updatelee

Parabolic as in a normal dish? Ya but those aren't as much fun to experiment with. Although I have wanted to make a pie plate dish for awhile now

I hate buiding parabolic antennas, it require a lot of patient to get mm precision, it´s hard to find the FC, etc. Waveguides antennas is much more simplier

There are few homemade dish on the net, i found this 1.8m dish in a chinese forum..google have strange translations, but i think this dish is performing like a 1.5m, which is pretty good.








Edit:

Not enough signal? just had some CD´s to your dish, and get +10% signal



This is one is made of CD´s

130% efficiency ?

Could be on track to develop the energy source of the future. Put in a gallon, get a a gallon And a liter. Captain Kirk would be proud!
I think what they meant was for the same dia, their sugar ant is 30% more efficient.
Efficiency above 100% is against the laws of physics. Most everything designed for it usually get 60 to 70. Automobiles, I think the number is, around 15%.(energy consumed - miles traveled)
Ok, dish,40% efficiency +(30% of 40) 12 =52% This would represent a ratio of 1.7333 which is the equivalent of 2.38874 dB.
2.38874 dB. is not worth the complexity and cost.
Give me 6 to 10db, and I'd think about it.

The one with the tubular frame reminded me of this:

Originally Posted by stogie5150

I have more levels, angle finders, compasses, machinists scales and such I should be able to BUILD a dish and mount from duct tape and cardboard boxes...

Originally Posted by Anole

Careful what you wish for.
There's a long and old thread over on the Aussie satellite site about doing that very thing.
In fact, the recent "Caribbean" (okay, Cuban) poster who showed us pix of his dish, obviously took his lead from that site.

Originally Posted by Anole

Vetrun.net
Hardware / Dishes
Sticky: 75cm Ku band dish construction

Jhonns2,
Very interesting concepts. With the political situations in some places around the world, it's intersting to see what some folks may have to resort to just to sneak a peek at news not controlled by their government, particularly where satellite equipment might be outlawed in the future. "When satellite is outlawed, only outlaws will have satellite". [My weird sense of humor]
Sky

jhonns2, Don't know if you're the one that posted the formula here:
Looking to build a c/ku-band horn antenna

These are the formulas to generate a conical horn (according to gain) all measures are in mm:

A= wavelength × ( 10^ ( (Gain+2.82)/ 20)

B= A/PI -this gives the diameter of the antenna

C= B×B / (3 × wavelenght)

D= SIN-1 × ( (0.5 × B ) / C )

E= 0.5 x (( B - Waveguide diameter ) / (Tang D) -> this gives the lenght of the cone


--------------------------------------
Example to confirm it: 26dBi , 11750Mhz , 25.5mm , Waveguide 19mm

A= 703.947
B= 224.073
C= 656.324
D= 0.1708
E= 594.4

I had a chance to run some numbers and "D" is a bit confusing. The sample D you get if you only use "( (0.5 × B ) / C )". If I read this correctly, the second part is multiplied by the sin of -1 which gives you -0.8414709848. That would make the answer in the sample D
-0.1437232442