advantages of horn antenna

Hello people do you know where I can find out some simple things that you cannot find in the antenna theory books. I need to know like:
an introduction on horn antennas,
why are they used, where, what is the advanteges of them, disadvantages.
where why they used. stuff like that easy stuff. What is the average gain of a horn antenna how do you get better gain?

thanks guys

here ur request

thanks a lot
I need more thanks

Added after 2 minutes:

I need more on the applications and advantages and disadvantages that major for me please thanks

try that

That is more theory but thanks I need somehtign very simple what are the advantages and disadvantages..Thanks for the info, but I need more info on advantages and dis and intro, history thanks

please can someone tell me what are the advantages of a horn antenna, what would be a average gain of a horn antenna or what would be a good efficiency? please I need this.

corrugated horn is the best one ,gain is depend on the aperture dimension.

anything else? what is a good average gai nfor horn antennas

corrugated horn can have an efficiency of over 90%. It has equal beamwidth at E and H plane. It is good selection as a feed for poarabolic reflector antenna

well what would be the disadvantages of a horn antenna? does anyone know where I can get a good picture of a horn antenna on a satelite? thank you

A very good and exaustive book is:
P.J.B. Clarricoats, A.D.Olver - "Corrugated horns for microwave antennas" - IEE Electromagnetic Waves Series 18 - 1984 Peter Peregrinus Ltd London.

Also, papers wrote by G. James and by P.J.B. Clarricoats from '70 and '80 years are important milestones.

Last, I would point your attention to the question you are asking.
Once accepted that corrugated horn is the most performant antenna used to feed a large reflector, it's size, weight, and phase center variation along axis may be choosen at the moment of reflector design rather than horn design because it's "optic" matter rather than horn related matter.

In other words:
- a prime focus illumination require smaller horn rather Cassegrain illuminators.
- a prime focus, High F/D ratio (i.e. 0.6) is more efficent rather than Low F/D ratio (i.e 0.3)
- a Cassegrain, low Magnificator Factor Dish Structure (i.e. 5) require a smaller and more phase stable horn rather than an high magnificator factor (i.e. 10)

hey sergio you are from italy? anche Io sono Italiano. My family is living rome. Is there any work for english speaking electrical engineer around Italy, I speak italian but not professionally. Please let me know and thanks for the info.

Added after 1 minutes:

just one question what is the differance between a conical horn antenna and pyramidal antenna? why use conical over pyramidal? what are advantages? thanks

about private questions, I'll answer You privately.

About the difference between conical and piramidal... well, each one form has it's own property, but is the illumination requirements that set the needed form of the horn.

Basically, corrugated horns have lower cross-polarization and cleaner (say low sidelobe) beam than smoot walled horns.

The conical corrugated horn is used where a perfect (say almost perfect) pencil beam is required, while piramidal ones are historically used as standard gain horn.
The word "standard" means metrologic measurent instruments; since the gain is well predictable by geometric dimensions. In other words the standard horn appear as mechanically very simple to build but it came with a certificate, so it's a very expensive device.

Recentely the conical corrugated horn has been proposed to became a standard.
The advantage is that the corrugated path inside the horn is very, very, very low loss (say 0.001 to 0.01 dB/m) , so i'ts omhic losses need to not be known. Also conical corrugated has tipically an extreme low reflection coefiicient (i.e -30dB).

For requirement that are asking a beamwidth large in one dimension but small on the other one (i.e 90° x 1°) a special rectangular horn is used. It's called "sectorial horn" . The simple description is a piramidal horn with thin and long rectangular aperture.
Placing the long side vertically, You may broadcast a land whitout loose energy on the sky or on the ground.