[Antennas] passive reflector ?

2003年8月02日 10:17:48 -0500

Hi Danilo,
I don't have the "simple formula" for you but have worked with them for 
years in the FAA, thank goodness the only maintenance is periodical 
mechanical alignment. There is no gain and in fact there will be a loss 
which is part of the total path loss for your link. From your post I 
assume, the TX/RX for each location has already extablished as well as the 
location for the passive reflector (passive repeater). With one RX/TX site 
being 4 km from the passive repeater site, the other 1 km. The angle which 
you say is 45 degrees has to be determined, and actually there is two angles 
to be considered. Are you saying that the beam angle from BOTH sites are at 
45 degrees from the reflecting surface is 45 degrees? Obviously there is a 
practical limit on the area of the reflecting surface (cost is always a 
limit). Both sites must illuminate the reflector, and the actual area of 
the reflecting plane is dependent on the angle the reflector makes with the 
beam. The reflector surfaces should be within 1/16 wavelength of the 
waveplane. To get the optimum angle(s) it would be nice if you had an 
assistant adjust the orientation of the reflector while you monitor the agc 
of the microwave receiver for maximum reading. You would need to 
communicate with your assistant to inform him that he has reached the 
optimum angle.
The path loss is determined by the formula 10 log {(wavelength to the 4th 
power times the distance of path 1 squared times the distance of path 2 
squared) divided by (projected area Tx times projected area Rx times area of 
the reflector surface)}
If the angle is 45 degrees I am suspecting the Rx projected area and the Tx 
projected area (assuming both angles are 45 degrees) are equal and would be 
.707 of the total area of the reflector.
Sorry I couldn't provide more info. Let me know what your final results are 
(you got me curious).
>From: "Danilo" <[email protected]>
>To: <[email protected]>
>Subject: [Antennas] passive reflector ?
>Date: Fri, 1 Aug 2003 23:22:30 +0200
>>Gentlemen,
>>does anyone has an simple formula
>for the microvawe passive reflector calculation?
>>E.g.:
>- qrg 1G2
>- d1 14 km
>- d2 1 km
>- angle 45 deg
>- TX 1 W
>- RX 0.5 uV
>>thanks, Danilo
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