I agree. This is one reason I always remove the frequency-dependent component when I do path loss analysis for a particular orbit.
73, Ken N2WWD
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Alan Bloom Sent: Monday, July 23, 2007 12:13 PM To: Rick Hambly (W2GPS) Cc: 'EAGLE' Subject: [eagle] Path loss (Was: A new opportunity (Phase 4 lite?))
On Sun, 2007-07-22 at 13:17, Rick Hambly (W2GPS) wrote:
- Use 10GHz as the region 1 downlink. This would require a new antenna
array and we would need to deal with the issues associated with the higher path loss while keeping things simple for our average users.
On Fri, 2007-07-20 at 17:42, John B. Stephensen wrote:
The increased gain of the earth station antenna compensates for the path loss.
Right. People say that path loss increases proportional to frequency (6 dB more path loss every time you double the frequency). But that is true only if you assume the antenna gain at both ends of the link is kept constant as you change frequency.
However, if you assume antenna APERTURE is constant with frequency, then path loss is actually INVERSELY proportional to frequency (6 dB LESS loss every time you double the frequency). In other words, for constant-size antennas, the higher the frequency the better.
So what does that mean for Eagle?
If you assume satellite antenna gain does not change with frequency (so as to keep the beam width just wide enough to illuminate the earth) and earth station aperture does not change with frequency (to keep the same dish size), then path loss is independent of frequency.
Al N1AL
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