Derek,
The horn antenna is an impedance matching device for getting between 50 ohm
lines and 377 ohm free space while launching TEM mode wave fronts.
You could use the commercially available one which has an awful antenna
factor. It's broadband as a result of the ribs placed in the horn.
Just guessing, but if you want 1 V/m which is around 2.7mW in free space
(4.3 dBm, 0.367Vac in a 50 ohm system) and your antenna factor is around
34dB, you'll have to power the antenna with 38.3 dBm (6.8W, 18.4Vac)
The antenna will probably take that.
However, if you want to get to 3V/m you'll then need (61W, 55Vac) and might
be overpowering the antenna.
For 10V/m you need (680 W, 184 Vac) Wow! Assuming 1 dB drop in your cabling
and you dissipate 70W there!
Sorry, don't know antenna design enough to tell you if you can improve that
antenna factor but my guess is no, or the EMC supply houses would have been
supplying those antennas already. The best bet is to go for octave band
antennas with only 10-16dB antenna factors and change the antenna a lot.
- Robert -
Robert A. Macy, PE [email protected]
408 286 3985 fx 408 297 9121
AJM International Electronics Consultants
619 North First St, San Jose, CA 95112
-----Original Message-----
From: [email protected] <[email protected]>
To: [email protected] <[email protected]>
List-Post: [email protected]
Date: Monday, March 06, 2000 12:55 PM
Subject: Horn Antenna
>
>Hi,
>
> I'd like to construct a wide band horn antenna covering from about 1 GHz
to 10 GHz or so.
>
> This is used only to generate a field inside a small EMC Chamber ( about 1
metre by 0.7 metres ), so I'm not worried about gain flatness etc.... I just
want field;-)
>
> Any thoughts about:
>
> 1) How these things work
>
> 2) The best way to go about modelling this
>
> 3) The best way to make one
>
> Thanks in advance
>
> Derek Walton
>
>
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