Interesting. How do you get them slightly out of phase? Is the difference in length of the LMR, enough? And is the distance apart the mechanism to increase downtilt, or the amount out of phase? I'm assuming distance apart?
Tom DeReggi RapidDSL & Wireless, Inc IntAirNet- Fixed Wireless Broadband ----- Original Message ----- From: "Chuck McCown - 2" <[EMAIL PROTECTED]> To: "WISPA General List" <wireless@wispa.org> Sent: Sunday, January 13, 2008 4:47 PM Subject: Re: [WISPA] 5.8 vertical antenna w downtilt > Two vertical collinear antennas. One mounted above the other. Fed > slightly > out of phase. You can have as much downtilt (or uptilt) as you want. > > ----- Original Message ----- > From: "rwf" <[EMAIL PROTECTED]> > To: "'WISPA General List'" <wireless@wispa.org> > Sent: Sunday, January 13, 2008 1:41 PM > Subject: Re: [WISPA] 5.8 vertical antenna w downtilt > > >> Thanks for the suggestion. >> >> I am not a fan of any omnis, really, but this needs to be an omni because >> this is a mesh AP. Not only that, it is a gateway or root (place where >> bandwidth is injected). I don't have the option of different RF hardware. >> An array would work, but I don't really want the (RX) loss from a power >> divider and an omni will do the job. It is a historic bell tower, used in >> many popular movies and the array would also be a lot harder to stealth. >> >> The reason I want severe downtilt is that in a mesh, you need to make >> sure >> that you don't make yourself heard by radios that are too far away >> because >> CSMA will keep both them and you from being able to transmit and will >> seriously harm the rest of the mesh. If I could get the antenna lower, I >> would. Unfortunately this is only mounting location choice to achieve LOS >> for this area. >> >> I am familiar with the 2 degree downtilt antennas, but for this case, I >> need >> much more that that I believe for this short of a range. >> >> >> >> -----Original Message----- >> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On >> Behalf Of Tom DeReggi >> Sent: Sunday, January 13, 2008 2:27 PM >> To: WISPA General List >> Subject: Re: [WISPA] 5.8 vertical antenna w downtilt >> >> Yes, to not use an Omni, but to use an Array. >> >> Max Rad made some of the first ones for 2.4G. >> Hyperlinktech makes some 4 sector arrays for 5.8Ghz. >> If needing only Verticle polarity, this is easy. Thats the configuration >> they sell them in. >> Will probably cost you around $600, for the kit with all antennas and the >> combiner. >> You could always make your own. >> >> With a mount hieght of only 50 ft though, not sure why this is a problem, >> if >> >> you are only needing to extend 1/10th of a mile coverage. >> A nice 10dbi Omni with 2 deg elect downtilt, Proxim makes one, or >> Tessco's >> terrawave Omni, would probably work just fine for that application. >> >> For such short range, even a 7-9db antenna would be fine, giving you a >> plenty large enough verticle beamwidth and high enough power. >> If its not good enough because of NLOS foliage or Noise, I'd argue you >> shouldn't be using an Omni in the first place. >> >> If a low bandwdith applications, as perfect application for a StarOS >> system, >> >> using 4 radios (or 3 radio in this app), each on their own 5 Mhz channel, >> using directional antennas using the Front to back ratio advantage, >> buying >> verticle pol 120 deg sector antennas for under $150 each. Its sometimes >> easier to do that, than get 1 channel to survive the noise in all >> directions. >> >> Tom DeReggi >> RapidDSL & Wireless, Inc >> IntAirNet- Fixed Wireless Broadband >> >> >> ----- Original Message ----- >> From: "rwf" <[EMAIL PROTECTED]> >> To: <wireless@wispa.org> >> Sent: Sunday, January 13, 2008 11:14 AM >> Subject: [WISPA] 5.8 vertical antenna w downtilt >> >> >>>I have an application where I need a 5.8 omni antenna with downtilt. >>> The coverage diameter of the area is only about 1/10th of a mile total, >>> and >>> my HAAT is about 50 ft so I will need some pretty severe downtilt. >>> Gain doesn't really matter, but a higher gain antenna is going to give >>> me >>> a >>> flatter pattern- I just need it to be tilted down. >>> >>> This is to keep an access point from interfering with a mesh deployment >>> further out that I want to protect as much as possible. >>> >>> Anyone got a suggestion for such an antenna.. >>> >>> Oh yeah- this has to be vertically polarized >>> >>> >>> >>> >> ---------------------------------------------------------------------------- >> ---- >>> WISPA Wants You! 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