Re: wifi-plus antennas, was VT problem
Jim Thompson <[email protected]>
| Newsgroups | gmane.network.wireless.seattle.general |
|---|---|
| Message-ID | <[email protected]> |
Franklin S Werren wrote: > Here is a good question.... about antennas > I am also very familiar with the DBS and the older BUD satellite systems > Why did the 2 DBS companies go with left hand and right hand circularly > polarized > antennas ??? Receiving the signal of a spinning satellite with either a horzontally- or vertically-polarized antenna will produce a rapid fading of the downlink. > And I did not by the over priced circularly polarized antennas that is > out there > for my link... I used the $80 specials 25 db gain antennas... > and they work even under snow.... unless it is wet.... > And that problem happens on the DBS satellite systems... > and the Big Ugly Dishes as well.... worse on ku.... > > > Franklin S. Werren www.bagpipes.net www.chautauqualake.net > > My 2 cents: Never get caught between an ISP and a telco in a pissing > match!! > The customer looses every time!!! > > > > > ----- Original Message ----- From: "Jim Thompson" <[email protected]> > To: "SeattleWireless Talk List" <[email protected]> > Sent: Wednesday, January 26, 2005 7:21 PM > Subject: Re: wifi-plus antennas, was VT problem > > >> David Josephson wrote: >> >>> It's too bad that the antenna people in this business so often make >>> their case with so much smoke and noise that the average user can't >>> tell what's real and what's fluff. Wifi-plus is nothing more or less >>> than stacked, radome-enclosed, more or less circularly polarized, >>> array antennas such as have been used for FM broadcast for 40 years >>> or more. There is some benefit to this, particularly in urban areas, >>> but no antenna is magic, and no antenna is going to make pine needles >>> and leaves disappear. Any antenna produces "gain" solely by directing >>> more of the power you feed it in one direction and less in others; a >>> circularly polarized antenna can actually result in lower signal >>> strength because part of the signal is radiated in a polarization >>> that isn't received by a given, optimal, receiving antenna. Over a >>> point-to-point link you're not going to do any better than well >>> matched parabolic antennas aligned to the same polarization. >> >> >> Well-said. Agreed, even. (Though if you match the polarizaion of >> any two antennas, you'll not see the effect you state.) That, and >> you'll need to restrict "do better" to "have more link margin", since >> the higher directivity may actually lead to more OBSS interference, >> since the other STAs won't see a high-enough signal level to set CCA. >> >> But I digress. >> >> I was 'holding back' not wanting to provoke a vendor war. >> >> There is a *lot* of BS in the wireless world. >> _______________________________________________ >> Talk mailing list >> [email protected] >> http://seattlewireless.net/mailman/listinfo/talk >> >> >> > > > _______________________________________________ > Talk mailing list > [email protected] > http://seattlewireless.net/mailman/listinfo/talk _______________________________________________ Talk mailing list [email protected] http://seattlewireless.net/mailman/listinfo/talk