Hello all, A few examples from VE7BQH Antenna Tables for 432 MHz (Excel interactive mode): Example 1. Tsky = 27 K, Tearth = 250 K (old value for very quiet condition). G/T result : RA3AQ AQ70-14f  6.73 dB KF2YN Boxkite 16  7.41 dB Example 2. Tsky = 27 K, Tearth = 458 K (rural condition). G/T result : RA3AQ AQ70-14f  6.24 dB KF2YN Boxkite 16  6.71 dB   Example 3. Tsky = 27 K, Tearth = 1794 K    G/T result : RA3AQ AQ70-14f  3.96 dB KF2YN Boxkite 16  3.82 dB        etc for any modeles... Vladimir, UR5EAZ. 31 января 2018, 10:57:23, от Justin via Moon-net <moon-net(a)mailman.pe1itr.com>om>: I think it is also important to note that the VE7BQH table G/T results are based (largely) on 4 antennas stacked to DL6WU formula spacing and G/T calculated in TanT with the antennas elevated at 30 degrees. Ideally, a set of 4 antennas is best optimised manually with perhaps the DL6WU spacing being used as a starting point. Yagis optimised for outright gain and those optimised for best signal to noise ratio behave differently and under or over stacking can cause ‘spike’ lobes or weird shaped rearward and down-facing patterns. Therefore, while a give array may give a very good figure in TanT at the default 30 degrees, it’s results when parallel to ground or at other elevations angles may not compare quite so favourably.   Justin G0KSC   From: Moon-net [mailto:moon-net-bounces@mailman.pe1itr.com] On Behalf Of Hartmut Kluever via Moon-net Sent: 29 January 2018 18:32 To: Fred Stefanik <n1dpmfred(a)gmail.com> Cc: Vladimir <ur5eaz(a)ukr.net>et>; John Regnault via Moon-net <moon-net(a)mailman.pe1itr.com> Subject: Re: [Moon-Net] Dec. 2017 1 yagi vs 2 yagi?   GE Fred,   sure, doesn't that example show in a nice way what happens when we increase the noise sphere temperature? The 'noisier' Yagi is still behind. The lower noise pickup one still in front G/T wise.   With the CC4218 the effect comes out clearly:   The CC4218XL compared to the 14 LFA: at 200 / 1000 K = the LFA is 0.56 dB/k ahead in antenna G/T at 200 / 5000 K = the LFA is 1.35 db/K ahead in antenna G/T   with mean you should in theory in average be able to rx by 1.35 dB more sensitive using a 4 bay of 14 LFAs compared to using a 4 bay of CC4218s in the 5000 K man-made noise environment.   Which be almost equal to using a LNA one with NF 0.5 dB, the other with 0.5 dB + 1,35 dB = 1.85 dB NF.   - - -   It is understood that all these are average or median figures and numbers. Very individual noise patterns might need other settings. If you have sole heavy source of noise just from the rear of your 'moon window' while the rest of the horizon is very quiet and that is your only application you be droping out of the averaging scheme and hence might look of max. F/B and F/R only apart from boresigth gain.   It further should be understood that the Yagi model and a real world build must match by means of a thorougly build Yagi with good matching correction factors. But this now is as you well know a necessity for whatever Yagi and no issue bound to the G/T tables especially.   vy73, DG7YBN, Hartmut - - - - - - - - - - - - - - - - - - - - - - - - More data? See "www.dg7ybn.de"     Gesendet: Montag, 29. Januar 2018 um 16:25 Uhr Von: "Fred Stefanik" <n1dpmfred(a)gmail.com> An: Vladimir <ur5eaz(a)ukr.net> Cc: "Hartmut Kluever" <dg7ybn(a)gmx.de>de>, "John Regnault via Moon-net" <moon-net(a)mailman.pe1itr.com> Betreff: Re: [Moon-Net] Dec. 2017 1 yagi vs 2 yagi? Looks to me like the G0KSC 14 LFA 3R is still the best with either TEarth of 1000K or 3000K. 73 Fred N1DPM   On Mon, Jan 29, 2018 at 10:46 AM, Vladimir via Moon-net <moon-net(a)mailman.pe1itr.com> wrote: Hello,   For example, of the difference Antenna G/T: 1. VE7BQH Antenna Table screen at Tsky = 200 Kelvin and Tearth = 1000 Kelvin:   Antenna G/T for CC4218XL = -1.48 dB/K. Antenna G/T for WB9UWA = - 1.61 dB/K.   In first place CC4218XL with minus 1.48 dB/K.   2. VE7BQH Antenna Table screen at Tsky = 200 Kelvin and Tearth = 5000 Kelvin:   Antenna G/T for CC4218XL = -3.71 dB/K. Antenna G/T for WB9UWA = - 2.45 dB/K.   In first place WB9UWA with minus 2.45 dBK dB/K.   Link:  http://www.bigskyspaces.com/w7gj/6mTable.htm     Vladimir, UR5EAZ.     --- Исходное сообщение --- От кого: "Hartmut Kluever via Moon-net" <moon-net(a)mailman.pe1itr.com> Дата: 28 января 2018, 13:25:31 Hello there,   could you please add this message to   Dec. 2017 [Moon-Net] Thread:   1 yagi vs 2 yagi?   Thank you in advance. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -   I see comments about the Antenna G/T tables that I like give some explanations to:   General and Stacking Distances:   The G/T table gives Antenna G/T at stacking distances per DL6WU as base number. It has to give at least G/T numbers at a shared base procedure as a basis for a direct comparison between variousy designs. In case the designer adds an own recommend for stacking E and H distances a row marked with an asterisk with these numbers is added.   Other stacking distances:   Individual under- or overstacking scenarios, simulated and or tested are very useful but would exceed what the tables can deliver. Hence F/R, 1st and 2nd sidelobe levels are given as a hepling number beyond being able to pick a less noisy design from the more noise pickup ones. For the very majority of designs i.e. patterns the one with less side and rear lobes will make the cleaner stack. So reading the antenna temperature and G/T ant DL6WU stacking for judging two designs on their possible performance when understacked (less distances compared to what the DL6WU formula gives) the one that produces better G/T still will when simulating both understacked. Same to the reciprocal way: using 15 percent larger distances the bay with lower antenna temperature and same G/T will still be 'less noisy'.   Sidelobes and F/R:   VE7BQH adds the following lines to the 144 MHz G/T Table: "Low sidelobe and F/R antennas with good (G/T) may provide further signifcant benefit if you have local man made noise that is in directions where these kinds of antennas provide additional suppression."   Re: John, G4SWX:   There is nothing mythical in computing Antenna G/T. It is a mathematical model and a set of formulas which are clearly layed out. Calculating antenna temperature and G/T is described in every serious antenna book as well as in a number of articles in the Dubus magazine starting with DJ9BV's "Effective Noise Temperatures of 4-Yagi-Arrays for 432 MHz EME" in Dubus 4/1987.   However what can be discussed are the individual as well as a increasing general man-made noise level quantities. Simply put the used number for T_earth in the G/T tables. For this the 144 and 432 MHz tables are 'interactive' since a few issues. The user can enter an own T_earth and all the antenna rows will adapt in antenna temperature and outcoming G/T. But anyway a Yagi that is producing a better G/T at a low level of man-made noise environment will produce an even clearer advantage in S/N with increasing noise level.   Use for extra-terrestrial and terrestrial communication:   As the use for EME is clear higher elevation angles very low angles need an eye on the 1st and 2nd sidelobe quantity. Which is why both numbers are given in the G/T tables.   Terrestrial communication now is different. Antenna temperature and the model to compute it draw their 'drive' from the difference in illumination of parts of the pattern by earth and sky hemisphere temperatures at elevation angles. With the boresight of a directional antenna towards the horizon there is an even illumination and the outcome in antenna temp. is just the mean temperature between T_sky and T_earth no matter what the pattern shape is. Nevertheless as the G/T number is a good index for directivity factor or simply put 'pattern cleaness' we can deduce the Yagi with the lower antenna temperature at same G/T to produce the better S/N in situations like a contest, heavy man-made noise at QTH and such. If only the major noise source does not come in from boresight direction / within the main lobe.   73, Hartmut, DG7YBN       - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -     vy73, DG7YBN, Hartmut - - - - - - - - - - - - - - - - - - - - - - - - More data? See "www.dg7ybn.de" _______________________________________________ Moon-Net posting and subscription instructions are at http://www.nlsa.com/nets/moon-net-help.html     _______________________________________________ Moon-Net posting and subscription instructions are at http://www.nlsa.com/nets/moon-net-help.html   _______________________________________________ Moon-Net posting and subscription instructions are at http://www.nlsa.com/nets/moon-net-help.html