₦airaland Forum

HI PEEPS!!!! I BEG OF U, ASSIST ME ON THIS!!!!

I am working on the effect of dish size on reception for my final year project. I was asked to get three to four satellite television antennas(Parabolic reflectors)of different diameters and put them on the same frequency bands(C band, Ku band and Ka band)and compare the effect of their different sizes on reception on each of these bands.

I found out that there is no substitute for more signals from a bigger dish; that a dish needs to be about 40% wider to produce twice the signal received; a 1.2m dish will give nearly 50% more signal than a 1m dish. I later saw a table from a footprint map giving the conventional sizes of dishes with their respetive EIRPs in dBW.It is depicted below.
EIRP(dBW) ; Dish Sizes(cm)
35 ; 300
40 ; 180
42 ; 160
44 ; 120
46 ; 95
48 ; 75
50 ; 60
51 ; 55
52 ; 50
53 ; 45
54 ; 40



It was concluded that EIRP IS A MEASURE OF SIGNAL STRENGTH. HOW WERE THESE EIRPs DERIVED FROM THE RESPECTIVE DISH SIZE? Yesterday, while in the library I found out that the satellite in space have their own EIRPs and also that the Satellite antennas on earth also have theirs.

Though, I saw a formula for EIRP Which is EIRP= Transmitter Power(dBm)+Antenna Gain(dB)-Feedline Loss. I perceive that this formula is for EIRPs of earth stations. BUT,HOW DO I CALCULATE THE TRANSMITTER'S POWER OF C BAND, KU BAND, AND KA BAN? IT'S NOT STATED ON THIS DISHES LNB OR MANUAL?

I quite know that the antenna gain is given as G= Antenna Efficiency x the square of(piD/Wavelength). Do not mind my representation, I can't write it properly at my end here. the antenna efficiency is presumed to be 55%, some say 70%, 80%? WHAT SPECFIC FREQUENCIES DO I USE IN THE RANGES OF C BAND, KU BAND AND KA BAND IN THE CALCULATION OF MY GAIN?

I quite know that the feedline loss is the losses in the coaxial cable and I read '75 Ohms RG U6' from a coaxial cable that connects the LNB to the decoder. I went online to check its rating, I saw that the 75 Ohmsindicated the impedance and I saw a voltage rating of 2700Vrms. The Power loss, I presume should be given as P=V squared/ Z i.e 2700 squared/75. THESE ARE MY PRESUMPTIONS, HOW DO I GO ABOUT IT?

THANK YOU!!!

KIND REGARDS!!

HOW DO I GO ABOUT IT WITH ALL I HAVE PUT ABOVE?

WHO IS GONNA HELP WID THIS?

I am working on the effect of dish size on reception for my final year project. I was asked to get three to four satellite

television antennas(Parabolic reflectors)of different diameters and put them on the same frequency bands(C band, Ku band and Ka

band)and compare the effect of their different sizes on reception on each of these bands.

I found out that there is no substitute for more signals from a bigger dish; that a dish needs to be about 40% wider to produce twice

the signal received; a 1.2m dish will give nearly 50% more signal than a 1m dish. I later saw a table from a footprint map giving the

conventional sizes of dishes with their respetive EIRPs in dBW.It is depicted below.
EIRP(dBW) ; Dish Sizes(cm)
35 ; 300
40 ; 180
42 ; 160
44 ; 120
46 ; 95
48 ; 75
50 ; 60
51 ; 55
52 ; 50
53 ; 45
54 ; 40



It was concluded that EIRP IS A MEASURE OF SIGNAL STRENGTH. HOW WERE THESE EIRPs DERIVED FROM THE RESPECTIVE DISH SIZE? Yeterday,

while in the library I found out that the satellite in space have their own EIRPs and also that the Satellite antennas on earth also

have theirs.

Though, I saw a formula for EIRP Which is EIRP= Transmitter Power(dBm)+Antenna Gain(dB)-Feedline Loss. I perceive that this formula

is for EIRPs of earth stations. BUT,HOW DO I CALCULATE THE TRANSMITTER'S POWER, IT'S NOT STATED ON THIS DISHES LNB OR MANUAL?

I quite know that the antenna gain is given as G= Antenna Efficiency x the square of(piD/Wavelength). Do not mind my representation,

I can't write it properly at my end here. the antenna efficiency is presumed to be 55%, some say 70%, 80%? WHAT SPECFIC FREQUENCIES

DO I USE IN THE RANGES OF C BAND, KU BAND AND KA BAND IN THE CALCULATION OF MY GAIN?

I quite know that the feedline loss is the losses in the coaxial cable and I read '75 Ohms RG U6' from a coaxial cable that connects

the LNB to the decoder. I went online to check its rating, I saw that the 75 Ohmsindicated the impedance and I saw a voltage rating

of 2700Vrms. The Power loss, I presume should be given as P=V squared/ Z i.e 2700 squared/75. THESE ARE MY PRESUMPTIONS, HOW DO I GO

ABOUT IT?

THANK YOU!!!

KIND REGARDS!!

HOW DO I GO ABOUT IT WITH ALL I HAVE PUT ABOVE?