[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

*Subject*: Re: [amsat-bb] todays math problem*From*: K5OE@xxxxxxx*Date*: Tue, 04 Feb 2003 03:29:41 -0500

Bob, One of the biggest factors in dish gain is the efficiency of illumination, but ignoring that complexity (since you didn't give us any specifics) and assuming a 50% efficient dish/feed combination in both cases, a convenient short-cut equation for "typical" dishes at 2.4 GHz is: Gain = Log10(0.256 * Area in sq in.) Thus: 791 sq in = 23 dBi and 1959 sq in = 27 dBi ...for a delta of only 4 dB. Roughly, each doubling of the dish aperture is worth 3 dB when all other variables are unchanged. 73, Jerry, K5OE/G In a message dated 2/3/2003 9:49:50 PM Eastern Standard Time, w7lrd@juno.com writes: > Hello > Bob has two dishes, dish 1 is 1959 square inches. Dish 2 is 791 square > inches. So dish 1 is about 2.5 times larger than dish 2. Bob thinks > dish 1 should be 7.5 db better than dish 2, that's 2.5X3db, > or maybe a > little over one S unit. Is Bob right? > > 73...Bob...W7LRD > Seattle ---- Sent via amsat-bb@amsat.org. Opinions expressed are those of the author. Not an AMSAT member? Join now to support the amateur satellite program! To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org

- Prev by Date:
**Uplink power on L-Band** - Next by Date:
**Re: AO-40** - Prev by thread:
**What can we do for NASA?** - Next by thread:
**Re: todays math problem** - Index(es):