Projects 
QO100 
Technology 


2020 

PrimeFocus The Prime Focus Antenna (parabolic antenna) is a satellite antenna which is perfectly round. It is absolutely symmetric built and has a parabolic shape. The focal point is in the middle of the dish. That's why the LNB is mounted centrally at the focus, where it can collect all incoming signals. Such a satellite antenna is typically larger than 1.2 meters. 
Advantages The Prime Focus Antenna (parabolic antenna) is a satellite antenna which is perfectly round. It is absolutely symmetric built and has a parabolic shape. The focal point is in the middle of the dish. That's why the LNB is mounted centrally at the focus, where it can collect all incoming signals. Such a satellite antenna is typically larger than 1.2 meters. 
Disdvantages Rain and snow can easily collect in the dish and could interfere with the signal. Because of the LNB is mounted centrally, a lot of the incoming signals are blocked by the LNB on the way to the antenna surface. 

Focus Reference: 
Another interesting formula for calculating the dimensions of a home made dish are given by: which is used for curvature calculations of the dish 

PA1A Ground Station Location 

Gain The gain of the paraboloid is a function of aperture ratio (D/λ) (D/lambda) D = The Diameter of the Dish (3m) k = ANT Efficiency 49.88% C = 299,792,458 m/s f = Frequency 24.15 GHz (0.01241377 m) 


Efficiency


F/D


Angle of Radiation Helix Angle = 2 * 

Beamwidth G is the gain over an isotropic source in dB D is the diameter of the parabolic reflector 
It is possible to estimate the beamwidth reasonably accurately from the following formula: All dimensions must be in the same units for the calculation to be correct, e.g. both diameter and wavelength in metres, or both in feet, etc. 

Beamwidth 
Antenna design is a compromise. The best large antennas do not have exact hyperbolic and parabolic subreflector and main reflector. They have slightly distorted shapes. The idea is to get a main dish illumination so that it is broadly flat but with a low in the centre, opposite to the subreflector obstruction, and low near and at the edges to minimise sidelobes. The pattern of a good dish may have highish first sidelobes (e.g. 13 to 15 dB) but these are at close angles off boresight that are less than the satellite to satellite spacing and then low sidelobes further out to meet the tight specified sidelobe mask, to minimise interference to and from other satellites.


Beamwidth PA1A The results of this calculations are only an approximate simulation. The professional method, which should give more exact results, uses complex antenna design software, but often still needs, as an input the measured pattern, power and phase angles of the feed itself. 
@3m PA1A Dish / @ 2.415 GHz / Efficiency = 48.5% 

EIRP 
ERP 

EIRP
It is the output power when a signal is concentrated into a smaller area by the Antenna. The EIRP can take into account the losses in transmission line, connectors and includes the gain of the antenna. It is represented in dB. Enter the transmitted power, cable loss and antenna gain to calculate the EIRP 


Calculation 

Used References: 1W = 30dBm An ideal isotropic radiator/antenna is used as the reference point. It emits power equally in all directions. If the antenna has a gain, this power gets concentrated in a particular direction. This is known as EIRP. The EIRP allows comparisons between different emitters regardless of type, size or form. If you know the EIRP and the gain of the real atenna, it is possible to calculate the real power and field strength. The calculator above calculates EIRP based on the Power, Gain and Losses that you enter. 

Helix Helical Antenna Design Calculator 1 Bauvorschlag DuoFeed Helix/LNB für HailSat QO100 von Günter DF2GB




Helix Feed für es'hail2 DJ0ABR  
>NEXT PAGE>  