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

[Christos Ricudis]

Hello Kostas!

  On 24 Oct 01, Kostas Liakakis wrote to Christos Ricudis with subject "Re: I
never thought I'd come to this, what's this aaaaaaaaall about?":

 >> poy den orizetai katey8ynsh, 8ewroume to maximum gain ths
 >> keraias, poy brisketai sthn koryfh toy main lobe - ekei 
 >> ekfrazontai kai ta 24dbi twn paraflextors.

 KL> Nai mana mou, alla auth ton 24dbi einai kateu0yntikh me euros 10
 KL> moires V kai 5-6 H.

Ma ayto akribws ekfrazei to noumero twn 24 db*I* - thn entash pediou metrhmenh
STON KYRIO LOBO, *anaforika* me thn isotropikh keraia. 

 >> 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.

 KL> Ego to exo diabasei san 14dbm. Einai 25mW. sto egrapsa.

To kserw matia moy, alla milas gia 25mW isxy ekpomphs - ase poy h ETSI orizei
ws maximum isxy ekpomphs 100mW, oxi 25 (kai ontws, de 8a breis poy8ena
/nomimws/ eksoplismo 802.11 me isxy ekpomphs megalyterh twn 100mW sthn eyrwph).
Epishs to regulation leei pws den mporeis na syndeseis tipote me gain anw twn
24dbi. me 100mW kai 24dbI, to power density sto 1 metro bgainei 0.199990958
mW/cm^2, poy einai poly konta sto 1991 IEEE standard for safety levels with
respect to human exposure to RF fields. Blepeis poy merikes fores ta standards
symfwnoyn metaksy toys? :> 

 >> Exoume 24db gain, opote :
 >>      30(mW)*10^(24/10)
 >> Pd = ----------------- = 0.0599972873 mW/cm^2
 >>      4*3.14*100(cm)^2

 KL> Eimape, den einai omni-directional, alla uni-directional. H omni
 KL> pou exo ypospin mou einai gyro sta 8dbi.

Akribws epeidh einai uni-directional exeis 24dbi *metrhmena sthn idia ey8eia me
ton kyrio lobo*. 

Sthn periptwsh ths omni-directional exeis akoma mikrotero power density (poy
einai apolytws logiko), kai bgainei 
    
     30(mw) * 10^(8/10)
Pd = ------------------- = 0.00150706372 mW/cm^2
     4*3.14*100(cm)^2

se apostash 1m apo thn keraia. (twra, se toso mikres apostaseis den kserw an
isxyei o typos, isxyei mono gia to far field, kai bariemai na briskw pws na
ypologizw poy einai to orio near/far field s'aytes tis keraies) 

--
Christos Ricudis

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