It's the KE5KAF Dstar system in Laredo. 2 Meters 120 watts after duplexers Telawave 4 cans 600 Split Coax LMR-400 80feet Antenna I want to put up is a Commercial Anitron-150 Similar to a DB220
--- In Repeater-Builder@yahoogroups.com, Nate Duehr <[EMAIL PROTECTED]> wrote: > > atms169 wrote: > > Hey guys, I'm trying to find radiation patterns or a calculator to see > > what would be the best possible coverage for our repeater. > > There's a number of calculators on the web, and some good links in the > RB website for Excel spreadsheets where you can see the math if you like. > > > We are in the very flat lands of Texas and our repeater is only up 50 > > feet (total of 530 above sea level). With 120 watt output. > > 120 watts after the duplexer loss, or before? What kind of duplexer, > feedline, etc. > > Assuming 50' for the transmitter and 8' (I'm being generous) for a > mobile rig, the radio horizon between those two is approximately 14 > miles, according to the popular calculators. > > Anything else isn't line of sight propagation. > > > Which do you think would work better? A dual folded dipole antenna > > with low angle of radiation or a fiberglass vertical at 6db? > > Let's assume power doesn't matter for a moment, and just break it down > into comparison of the antennas. > > Remember, altitude trumps all, antenna gain and feedline losses next, > and the PA is *last* place you want to make up for a weak antenna > system. The antenna is gain both directions, transmit and receive. The > PA only helps people hear the repeater... it doesn't help them get into it. > > So... the important info is missing in your question... > > What band? Can't answer the antenna question without knowing what band > you're looking at to compare different sized antennas. Makes a big > difference. I will assume VHF for these answers for the moment. > > You say 6dB. Is that 6 dBd or 6 dBi? That also makes a big difference, > since we're going from your numbers for the one antenna, and don't know > which other antenna you're comparing to. > > What specific antennas are you looking at? Spec sheet on the web > somewhere to reference? For both... the dipole array and the stick. > > Most dual-dipole-array antennas claim about 6 dBd gain when set up in an > elliptical pattern. That assumes a 1/2 wave spaced (from the mast) > dipole array, like this Sinclair: > > http://www.sinclairtechnologies.com/catalog/product.aspx?id=1680 > > There are different configurations for 1/4 wave spaced (from the mast) > dipole arrays, the lowest gain being the purely omni-directional setup. > The "offset" setup where you pick a direction to "push" your RF one > way more than the others, gives you a little more gain that direction at > the expense of the other side. > > http://www.sinclairtechnologies.com/catalog/product.aspx?id=326 > > Generically, there's no free lunch. The same sized antennas exhibit > much the same gain, but you can do tricks with the dipoles a stick can't > do... like offset the pattern a bit. > > You could always go for an enormous VHF corner-reflector! > > (Yep, they make 'em...) > > http://www.sinclairtechnologies.com/catalog/product.aspx?id=1403 > > It's ONLY 10' wide... hahaha... > > More info needed... the devil is in the details. > > Nate WY0X >
