I never thought I'd come to this, what's this aaaaaaaaall about?

[Christos Ricudis]

Hello Kostas!

  On 23 Oct 01, Kostas Liakakis wrote to Christos Ricudis with subject "Re: I
never thought I'd come to this, what's this aaaaaaaaall about?":

 KL> H keraia exei kapoio kerdos (gain). Me alla logia enisxuei thn
 KL> ekpomph. Opos blepeis akomh kai h mh kateu0yntikh exei gain 8dbi. 
 KL> H plhros kateu0yntikh, exei 24dbi gain mias kai ekpempeis pros 
 KL> mia sygkekrimenh kateu0ynsh.

H keraia enisxyei thn ekpomph. Mprabo, molis parabiases thn arxh diathrhshs ths
energeias (ontws, telika ekanan la8os :>). 

Ayto poy allazei einai h pyknothta isxyos, Watts/m^2, kai akribws ayto
ekfrazei to gain. To gain einai o logos ths isxyos poy apaiteitai sthn eisodo
ths keraias mas pros thn isxy eisodou mias isotropikhs keraias wste h entash
toy HM pediou sthn idia apostash na einai idia stis dyo keraies. Se periptwsh
poy den orizetai katey8ynsh, 8ewroume to maximum gain ths keraias, poy
brisketai sthn koryfh toy main lobe - ekei ekfrazontai kai ta 24dbi twn
paraflextors.

H pyknothta isxyos ths isotropikhs keraias se apostash R einai Pdi = Pt/4pR^2.
H pyknothta isxyos ths katey8yntikhs mas keraias me gain G se apostash R,
einai Pd=Pt*G/4pR^2

To orio asfaleias ths IEEE gia pyknothta isxyos einai peripoy 1mW/cm^2 se mh-
elegxomeno periballon. H wavelan kartoula moy exei megisth isxy ekpomphs
nomizw gyrw sta 30 mW.

Epeidh to komodino moy apexei arketa apo to krebbati, h keraia de mporei na
mpei se apostash mikroterh toy enos metrou (100cm) gia na stoxeyei to kefali
moy, ara ypologizoume power density sto ena metro.

Exoume 24db gain, opote :


     30(mW)*10^(24/10)
Pd = ----------------- = 0.0599972873 mW/cm^2
     4*3.14*100(cm)^2

Gamwto, ayto shmainei oti den prokeitai na pa8w karkino akoma?



--
Christos Ricudis

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