the best was neither vert or horizontal, and continously changing, well slowly changing faraday rotation. plus why would you want to aste n extra 3 db if you have it to be used?
Joe WB9SBD The Original Rolling Ball Clock Idle Tyme Idle-Tyme.com http://www.idle-tyme.com On 4/1/2010 2:27 PM, Mark Lunday wrote: > Would this also be accomplished in "poor man's design" by simply having one > yagi vertical and one horizontal? > > > Mark Lunday > WD4ELG > Greensboro, NC - FM06be > [email protected] > http://wd4elg.net > http://wd4elg.blogspot.com > > > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of Idle-Tyme > Sent: Thursday, April 01, 2010 1:53 PM > To: [email protected] > Subject: [amsat-bb] Re: Arrow and EME? > > Another very important thing is polarity. > the ability to change polarity can easily me a completed QSO or one > where not a peep was heard. > > In the late 80's early 90's I had a small station of 4 eight element 2 > meter yagis. I think they were a W1JR design? > > anyway I mounted them in a way that i could rotate them in polarity also. > > It was amazing I never thought i could do moonbounce with them but just > for kicks was listening down at the bottom of the band one day and heard > someone CQing and wortking someone off he moon. of course it was W5UN. > but a random call when he finished and we had a complete QSO in the log > with no repeats solid exchange both ways! > > what make this amazing was I was using a kenwood TS700 rig into a old > KLM (remember KLM amps?) a 70 watt one that was tired and only putting > out about 35 watts, into a run of rg 213 50 feet to the antenna, no pre > amps at all. and on CW by ear! no filters either just the standard 2.XX > whatever wide filter. > But the polarity made all the difference! In horizontal mode i heard > NOTHING. but somewhere inbetween H and V he wa solid copy and he had no > problem hearing me too. > > I eventually went on to work about 30 other stations as small as other 4 > yagi stations. The ability to make polarity changes is a GIANT advantage! > > Joe WB9SBD > > The Original Rolling Ball Clock > Idle Tyme > Idle-Tyme.com > http://www.idle-tyme.com > > On 4/1/2010 12:11 PM, Mark Lunday wrote: > >> I have been doing some reading on this also. Although I have not yet made >> any EME contacts, I have been uncovered the following: >> >> 1. Moonrise/moonset will enhance signals because of ground reflections, >> something like 6 dB. Many folks intentionally use moonrise and moonset >> attempts for this reason. >> >> 2. Mast mounted pre-amp is essential >> >> 3. Higher frequencies need more gain (so I have been told). But the 440 >> > MHz > >> part of the arrow antenna should have a LOT more gain than the 2 meter >> > part. > >> 4. Low loss coax is very important, esp at VHF. Keep the runs short and >> > use > >> something equiv to LMR 400 (50 foot of the good stuff is probably under >> $100, and worth it. >> >> 5. Definitely try to set up a sked with W5UN. If you can hear him, then >> > you > >> are halfway there! >> >> 6. Monitor websites like http://www.chris.org/cgi-bin/jt65emeA >> >> 7. 2010 appears to be a promising year for EME, here is a good calendar: >> http://www.vhfdx.net/w5luu.html >> >> >> Mark Lunday >> WD4ELG >> Greensboro, NC - FM06be >> [email protected] >> http://wd4elg.net >> http://wd4elg.blogspot.com >> >> >> >> -----Original Message----- >> From: [email protected] [mailto:[email protected]] On >> Behalf Of MM >> Sent: Thursday, April 01, 2010 8:37 AM >> To: [email protected] >> Subject: [amsat-bb] Arrow and EME? >> >> Arrow Antenna and EME: >> >> It is possible to work Earth Moon Earth with an Arrow Antenna. >> >> Of course, it is. You just need to make a schedule with someone on the >> other side of the link with enough Antenna Gain. You also need to be >> running the new digital text messaging mode called JT65B >> >> Link for JT65 >> http://www.physics.princeton.edu/pulsar/K1JT/ >> >> Definitions: >> In this document I will refer to all antenna gain values based on the >> > number > >> of elements. >> >> Example: A Single half-wave Dipole = 0 dBd >> Elements 2 = 3 dBd >> Elements 4 = 6 dBd >> Elements 8 = 9 dBd >> Elements 16 = 12 dBd >> >> The Arrow antenna (Model 146/436-10) has 3 elements on the 2-meter band, >> > so > >> its maximum theoretical "Element Gain" is 4.5 dBd. >> >> With the invention of the JT65 protocols, thousands of Amateur Radio >> stations running a Single Yagi 2-meter antennas, now have access to the >> > Moon > >> and EME contacts. >> >> To make a contact on Moon bounce, the "Total Antenna Gain" from both >> stations is added up and will need to be in the approximate range of >> > 25-30 > >> dBd. With this gain and the average transmitter power of (100-400 watts) >> you will have a 10-20+ percent chance of completing a 2-way EME JT65B >> > link, > >> with another station. >> Note: There are many other factures used in EME gain calculations. For >> simplicity, we will just focus on the antenna Gain. >> >> The amount of Total Antenna Gain required depends on the mode you wish to >> use. The wider the mode, the more gain that is required. The mode JT65B >> > is > >> a very narrow mode and requires less gain. I am not going to go over all >> > of > >> the details of JT65 in this article, look it up. >> >> Gain required by mode: (All values are approximate) >> >> JT65 28-30 dBd (1-Yagi + 4-Yagi) >> CW 30-40 dBd (4-Yagi + 4-Yagi) >> SSB 40-50 dBd (8-Yagi + 8-Yagi) >> FM 60-70 dBd (16 + 24) Guess >> >> >> The Mode JT65B requires approximately 30 dB of Total Antenna Gain for an >> > EME > >> contact. >> If we assume the average 12-element 2-Meter Yagi has 10.5 dBd (round to 11 >> for easy math) of "Element Gain", then the more Yagi's you stack, the >> > more > >> gain you will have. In EME lingo, 1x12 means, you have One Yagi, with 12 >> elements, 4x12 means you have a stack of 4 yagis with 12 elements each >> > (48 > >> elements total) and an approximate gain of 17 dBd. >> >> 1-Yagi = 11 dBd >> 2-Yagi = 14 dBd >> 4-Yagi = 17 dBd >> 8-Yagi = 20 dBd >> 16-Yagi = 23 dBd >> 32-Yagi = 26 dBd >> 64-Yagi = 29 dBd (W5UN) >> >> >> A Single-Yagi station (11 dBd) calling a 4-Yagi (17 dBd) station will >> > have > >> approximately 28 dBd Total Antenna Gain. The 4xYagi stations are very >> common on JT56B EME. >> >> Let's go back to the Arrow Antenna: >> >> We need 30 dBd of total antenna gain. >> The Arrow antenna has 4.5 dBd. >> The Arrow also has a Maximum power limitation of 150 watts (10 watts if >> > hand > >> held). >> >> If you are running the maximum 150 watts on your Arrow antenna, you >> > should > >> be able to work stations with 32 to 64 Yagi's. There are not very many 64 >> Yagi stations out there, however Dave W5UN has been active on JT65 EME >> recently. >> >> If you want more of a challenge, you can try QRP at 5 watts and your Arrow >> antenna. >> Reducing you power from 150 watts to 5-10 watts, will reduce your >> performance by 12 db. >> To compensate for the reduce power, you will just need to find a station >> with a bigger antenna. >> >> There is another big gun on EME. Two weeks ago, Arecibo was on EME, >> > running > >> CW, working EME stations on the 440 band. The antenna used at Arecibo is >> > a > >> simple 1,000 foot dish. The actual gain for 2-meters is not known, >> > however > >> I will assume it is more than 64-Yagi's. >> >> http://www.naic.edu/ >> >> So here is your chance. Make a schedule with Arecibo and go for QRP, EME, >> with a held Arrow antenna, or if you know of any good contacts at Arecibo, >> send me the data and I'll try to arrange a schedule and try it from my >> station. >> >> Other Hardware: >> A good Receiver Preamp (similar to ARR) >> http://www.advancedreceiver.com/ >> >> A good SSB 2-meter Transceiver (the best ever made Yaesu FT-736R) >> http://www.xs4all.nl/~ketel/ham/ft736.htm >> >> Good Coax (RG-8 coax is 11 Millimeter coax. That is ok for 50' EME runs, >> for longer runs use 12+ Millimeter coax) >> >> 73 >> >> WF1F >> www.marexmg.org >> >> >> >> >> >> >> >> >> >> _______________________________________________ >> Sent via [email protected]. Opinions expressed are those of the author. >> Not an AMSAT-NA member? Join now to support the amateur satellite program! >> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb >> >> _______________________________________________ >> Sent via [email protected]. Opinions expressed are those of the author. >> Not an AMSAT-NA member? Join now to support the amateur satellite program! >> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb >> >> >> >> > _______________________________________________ > Sent via [email protected]. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > > > > _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
