For FDD systems that require a minimum frequency separation between Transmitters and receivers, one should always follow a standard high/low frequency plan. In fact for efficient use of the band for all parties, the high/low plan should be followed religiously. Violating the established high/low is referred to as a high/low “buck” or “bucking” station and doing this makes it much harder for the next path planned at the site, as the interference potential would now be co-located rather than at the far-end.
If you’re connecting into established sites or mountain tops, it’s sometimes required to have a buck in order to match the prevailing plan at the established site. In these instances, one would want to have as much frequency separation as possible between T & R at the co-located site. Sent from my iPad Sent from my iPad > On Mar 13, 2020, at 8:38 PM, Tim Hardy <thardy...@gmail.com> wrote: > > The radios certainly don’t have any isolation from this type of > interference, so what you’re relying on is totally on the antennas - there’s > not much FSL on these and I wouldn’t bet my life on a 2’ Category B to > provide the kind of close-coupling loss needed on a co-located system. AT&T > and MCI used to do it when they had completely back-to-back horns or > ultra-high performance antennas but they provide about 80 dB of > discrimination front-to-back. > > Sent from my iPad > >>> On Mar 13, 2020, at 8:31 PM, Colin Stanners <cstann...@gmail.com> wrote: >>> >> >> To my knowledge the radios and dishes have enough isolation that H/L match >> at a site is not necessary unless you're almost pointing in the same >> direction with those dishes (or have a TX frequency at one site overlapping >> a RX) . The opposite polarity increases the isolation so you have even less >> worry in this case. That H/L match idea is more of a tendency and to >> simplify planning than a rule. >> >>> On Fri, Mar 13, 2020, 6:52 PM Ken Hohhof, <af...@kwisp.com> wrote: >>> I am having some 11 GHz links coordinated and the draft PCNs they sent me >>> have one site high on one link and low on the other link. They are however >>> different sub bands, and one is HPOL and the other is VPOL. Does this make >>> it OK? I could probably do one of the links in 18 GHz. >>> >>> >>> >>> I had internalized the idea that you never had high and low at the same >>> site. >>> >>> -- >>> AF mailing list >>> AF@af.afmug.com >>> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> -- >> AF mailing list >> AF@af.afmug.com >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com
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