Fibo 1.2m v Channel master 1.2m

Riverblue

Regular Member
Joined
Jul 25, 2012
Messages
598
Reaction score
419
Points
63
Age
62
My Satellite Setup
See Signature
My Location
Near Brighton
I was chatting to a guy the other day that was trying to sell his beaten up Fibo 1.2m dish and he reckoned that it had the performance of a 1.8m dish :rolleyes: Now I'm no expert but I know that when it comes to satellite dishes there is no substitute for size, so I cannot see how a Fibo can be that good! But it did get me thinking, I have a Channel Master 1.2m which I'm very happy with, but how does it compare with a Fibo 1.2m? How do the two heavyweights of the 1.2m department measure up against each other, which gives the most with a like for like install (if possible) the Channel Master 1.2m or the Fibo 1.2m? Are they both of similar size? What are the advantages of the "gregorian" dish over an offset dish, if any? I know there are members of this forum that have one or the other of these dishes, but what about those that have both, or have had both, what's your opinion or experience of these dishes? :)
 

AndyX

Member
Joined
Sep 26, 2005
Messages
326
Reaction score
342
Points
63
Location
Scotland
My Satellite Setup
TM-F3/5
Octagon SF4800
Octagon SX88
Fibo Gregorian 1.2m
Motec Positioner
Inverto c120 twin LNB
My Location
Central Scotland
I have the Fibo 1.2m dish. I would say it has the performance efficiency of 1.4m dish. It has a sub reflector which catches the signal from the main reflector refocusesand it before bouncing the signal into thelnb. Full details are below:
Offset antenna efficiency calculator
Antenna Beamwidth@11.7GHz1,45 degrees - 1,5 degrees theoretical
Antenna Offset18 degrees
Waveguide FlangeC120
Reflector typeGregorian offset - two reflectors
Antenna MaterialAluminium
Antenna surface & feedsupportCrom & epoxy
Polarmount+/-90 degrees
Weight11 kg
Elevation range30-75 degrees
Declination range30-75 degrees
Wind speed limit
Pipe for Polarmount/Fixed mount76mm X 5mm
Bolts on reflectorM8
Distance between bolts205x170
Suited LNBsInvacom C120 Single,Twin,Quad etc., MTI AP8-TW,Digistar SC-1
LNBs that does NOT fitDigistar TC-22,MTI AP82-TW,MTI-AP84-TW
 

sonnetpete

Grumpy Old Retired Moderator and quiz inquisitor..
Joined
Dec 13, 2008
Messages
8,954
Reaction score
3,497
Points
113
Age
73
Website
wordpress.com
My Satellite Setup
Laminas 1.2M fibre dish with an IBU, on a Clarke Tech USALS motor, covering 57E - 24.5W to an Octagon SX88. Displayed on a 20" Dyon LED TV.

Seperate 80 cm dish on 28E with a Humax Freesat for SWMBO.
Free Sat V8 meter. Sony Bravia 46" LCD, Sony BluRay and Home Cinema.
My Location
Normandy, France

CROSSBONES

Specialist Contributor
Joined
Jul 23, 2005
Messages
2,009
Reaction score
192
Points
63
My Satellite Setup
1.2m channel master on a jeager 1224 motor. 55cm fibo Gregorian. VU solo2.
My Location
S.Wales
The fibo is 1.4m tall and 1.2m across.
It is also said the 55cm Fibo performs like an 80cm.
 

RimaNTSS

Super Moderator
Staff member
Joined
Jan 7, 2009
Messages
5,614
Reaction score
6,101
Points
113
Age
58
My Satellite Setup
Some SAT-related hardware.
My Location
N-E from Riga
Hi! I like this topic!
Before we start to compare different sat-systems, could we agree on methodology how to do measurements and then compare results with final goal to be able to say something like this: System A performs 10% better than system B!
Any ideas?
I have several offset, prime-focus and Gregory dishes and for long time wish to find formula how to compare their performance.
Last summer I did some measurements on 1,8m offset dish and then converted it to Gregorian type, and according to my way of thinking got up to 8% of improvement.
I only think I was calculated %% not the way they should be calculated.
Topic is here
 

Riverblue

Regular Member
Joined
Jul 25, 2012
Messages
598
Reaction score
419
Points
63
Age
62
My Satellite Setup
See Signature
My Location
Near Brighton

CROSSBONES

Specialist Contributor
Joined
Jul 23, 2005
Messages
2,009
Reaction score
192
Points
63
My Satellite Setup
1.2m channel master on a jeager 1224 motor. 55cm fibo Gregorian. VU solo2.
My Location
S.Wales
Yes but the Fibo looks nicer IMO :D
 

hvdh

Specialist Contributor
Joined
Dec 10, 2004
Messages
2,365
Reaction score
3,351
Points
113
Age
60
Website
gso-satellites.nl
My Satellite Setup
Dr.HD F16, TBS 5927, T-55, Laminas 120 cm
My Location
Oss, NL (5.5°E 51.8°N)
Theoretical advantages for reception, of gregorian style dishes over offset dishes:
LNB overspill is more into the cold sky, instead of warm walls etc. (Depending on install location.)
No cross-polarisation degradation.
 

RimaNTSS

Super Moderator
Staff member
Joined
Jan 7, 2009
Messages
5,614
Reaction score
6,101
Points
113
Age
58
My Satellite Setup
Some SAT-related hardware.
My Location
N-E from Riga
I think, theoretically and practically Fibo1,2m (not warped) will outperform CM1,2m (can not be warped). And this out-performance will be 5-10%.
But, at the same time, CM1,2m with properly designed and attached subreflector will perform not worse than Fibo 1,2m.
 

Riverblue

Regular Member
Joined
Jul 25, 2012
Messages
598
Reaction score
419
Points
63
Age
62
My Satellite Setup
See Signature
My Location
Near Brighton

BlindFaith

Specialist Contributor
Joined
Oct 2, 2011
Messages
639
Reaction score
309
Points
63
Age
43
My Satellite Setup
-
120cm Echostar and 70cm (2nd location)
TBS 5925
My Location
52,0°N, 4,3°E and 52,5°N, 13,4°E
90cm = 110cm operating at 122.22%

55cm = 80cm operating at 145.45%

Sounds like speculation to me, or the larger dish is nowhere near as effective, probably the former.

Well, you haven't done your maths correctly ;) You have to compare the area and not the diameter :)
 

Riverblue

Regular Member
Joined
Jul 25, 2012
Messages
598
Reaction score
419
Points
63
Age
62
My Satellite Setup
See Signature
My Location
Near Brighton
Well, you haven't done your maths correctly ;) You have to compare the area and not the diameter :)
Even as a rough calculation (which it was) the figures would still be about the same as working out the area exactly and comparing them percentage wise . . . There would be a vast difference between "the claimed" performance of these dishes that doesn't equate when you scale them up. In other words something is not right with these claims!

Doing the maths properly . . area = π(length a/2)(length b/2)
90cm (0.69979m²) = 110cm (0.88844m²) Triax td110 = 126.96%

55cm (0.25918m²) = 8ocm (0.42883m²) Technomate TM80cm = 165.46%
 

Trust

Specialist Contributor
Joined
Jul 18, 2004
Messages
1,134
Reaction score
1,619
Points
113
Age
77
My Satellite Setup
1.8 m CM at SMR 1224 + Elev. with 7 lnb changer Ku (lin - circ) - Ka (lin - circ) C (lin - circ)
My Location
Nijmegen Netherlands
Have to dissapoint some people , made a test against my Fibo 120 years ago wenn Laminas came with his first OFC 1200
Both equipt with BU single lnb , no difference between them at Nilesat .
A member at a dutch board claims to have a better signal on his no-name 120 offset dish , he is living ± 50 km more south to me .
 

BlindFaith

Specialist Contributor
Joined
Oct 2, 2011
Messages
639
Reaction score
309
Points
63
Age
43
My Satellite Setup
-
120cm Echostar and 70cm (2nd location)
TBS 5925
My Location
52,0°N, 4,3°E and 52,5°N, 13,4°E
@Riverblue, you don't have to take the length into account, cos from the satellite an offset dish is seen as a circle.

It's only the width that counts. The gain is proportional to the effective area of the dish. Comparing 110cm to 90cm yields a theoretical gain of -> 20log(110/90)= 1,74dB and 80cm /55cm -> 3,25dB

@hvdh has described the advantage of a gregorian dish correctly. The effective area is increased due to a more precise illumination. But don't believe in wonders ;)
 

BlindFaith

Specialist Contributor
Joined
Oct 2, 2011
Messages
639
Reaction score
309
Points
63
Age
43
My Satellite Setup
-
120cm Echostar and 70cm (2nd location)
TBS 5925
My Location
52,0°N, 4,3°E and 52,5°N, 13,4°E
@Trust1, IMHO it's not that easy to compare the dishes. A gregorian dish normally comes with a matched feedhorn which could give an additional advantage compared to a standard offset-LNBF.
 

Captain Jack

Retired human
Joined
Oct 21, 2006
Messages
11,826
Reaction score
8,014
Points
113
My Satellite Setup
See signature
My Location
North Somerset
I have made practical comparisons between a 1.2m Channel Master and a Fibo. Bottom line - the Fibo is slightly better than the CM but only just. And my 1.5m Gibby walks all over the Fibo. Search for my thread title 'Fibo project' and it will be on the 4th or 5th page. Can't do it here as I am in bed on my phone.

It's a good, efficient dish but it doesn't perform magic tricks.
 

RimaNTSS

Super Moderator
Staff member
Joined
Jan 7, 2009
Messages
5,614
Reaction score
6,101
Points
113
Age
58
My Satellite Setup
Some SAT-related hardware.
My Location
N-E from Riga
And, as I mentioned before to compare dishes you have to have
Fibo1,2m (not warped)
But, unfortunately, after so many years and stormy days it is not so easy to find Fibo in ideal shape (except Fibo55, cuz they seem unbreakable).
 

Riverblue

Regular Member
Joined
Jul 25, 2012
Messages
598
Reaction score
419
Points
63
Age
62
My Satellite Setup
See Signature
My Location
Near Brighton
@Riverblue, you don't have to take the length into account, cos from the satellite an offset dish is seen as a circle.

It's only the width that counts. The gain is proportional to the effective area of the dish. Comparing 110cm to 90cm yields a theoretical gain of -> 20log(110/90)= 1,74dB and 80cm /55cm -> 3,25dB

@hvdh has described the advantage of a gregorian dish correctly. The effective area is increased due to a more precise illumination. But don't believe in wonders ;)
Sorry to be a thicko but could you explain your calc to me please, how do you get dB? What is 20log?
Okay, my methods may be wrong but even so your calcs still show a disproportionate amount of gain re difference in size, if I'm understanding them correctly. Which still suggests that one of these claims is wildly inaccurate, or am I interpreting this all wrong?:confused
 

Captain Jack

Retired human
Joined
Oct 21, 2006
Messages
11,826
Reaction score
8,014
Points
113
My Satellite Setup
See signature
My Location
North Somerset
20log is a logarithmic scale - can be found on most ' scientific' calculators. Been a long time since I had to do those types of calculations!
 

Riverblue

Regular Member
Joined
Jul 25, 2012
Messages
598
Reaction score
419
Points
63
Age
62
My Satellite Setup
See Signature
My Location
Near Brighton
Having just "googled" for more info on logarithmic calcs and non linear scales I can honestly say that my head hurts, it must be all that extra gain in knowledge! :-wow Unfortunately it's about as clear as mud :confused
 
Top