At 02:25 AM 9/28/2006 +0000, w7lrd@comcast.net wrote:
Hello How much gain can I expect to get from a 36x30 inch primestar dish. Also
a 54X48 ps dish? I plan to use a 5-6 turn helix feed. I've been googleling around and I can't find out. I have some 7/8 hardline I'll use from my IC-1271A running 10 watts.
73 Bob W7LRD Seattle
Since the dishes are elliptical standard formula for a circular parabolic dish will not properly calculate gain. But if you use the smaller dimension as a diameter in those formula you should come up with the minimum gain.
Using 30-in, gain = 24.1 dBi at 2401 MHz Using 48-in, gain = 29.2 dBi at 2401 MHz, gain = 23.7* dBi at 1268 MHz
* Note: The smaller dish is too small at 1268 MHz and the larger dish may not produce this gain since it < 10 wavelength in diam. 73's, Ed - KL7UW ========================================= http://www.qsl.net/al7eb - BP40iq 144-EME: FT-847, mgf-1801/1402, 4xM2-xpol-20, 170w 432-EME: FT-847, mgf-1402, 1x21-ele (18.6 dBi), 60w =========================================
Using 30-in, gain = 24.1 dBi at 2401 MHz Using 48-in, gain = 29.2 dBi at 2401 MHz, gain = 23.7* dBi at 1268 MHz
- Note: The smaller dish is too small at 1268 MHz and the
larger dish may not produce this gain since it < 10 wavelength
in diam.
I can vouch for that. We just finished a lab where we used some of the little 1.2 and 2.4 GHz TV cameras as signal sources and then used a 24" DIRECT TV dishe to let the students measure the gain between a dipole and the dipole on the dish.
You are correct. There is no meaningful gain at 1.2 GHz. 2.4 GHz gain was striking. I'll wait to see their data before I commit to how much gain we got at 2.4 GHz.
Bob, WB4APR
participants (2)
-
Edward R. Cole -
Robert Bruninga