Date: Wed, 26 Oct 94 04:30:20 PDT From: Ham-Ant Mailing List and Newsgroup Errors-To: Ham-Ant-Errors@UCSD.Edu Reply-To: Ham-Ant@UCSD.Edu Precedence: List Subject: Ham-Ant Digest V94 #356 To: Ham-Ant Ham-Ant Digest Wed, 26 Oct 94 Volume 94 : Issue 356 Today's Topics: ACURATE ROTATORS ??? double delta loop on 2 meters Needed: J-pole measurements Phased array antennas Racal Radio's Re : double delta loop on 2 meters what IS a bevrage antenna? where do I go for local antenna laws Send Replies or notes for publication to: Send subscription requests to: Problems you can't solve otherwise to brian@ucsd.edu. Archives of past issues of the Ham-Ant Digest are available (by FTP only) from UCSD.Edu in directory "mailarchives/ham-ant". We trust that readers are intelligent enough to realize that all text herein consists of personal comments and does not represent the official policies or positions of any party. Your mileage may vary. So there. ---------------------------------------------------------------------- Date: Mon, 24 Oct 1994 22:36:46 GMT From: mack@ncifcrf.gov (Joe Mack) Subject: ACURATE ROTATORS ??? In article itbkl@puknet.puk.ac.za (Keith Laaks) writes: >HI. > >I habve started to experiment with Moonbounce (EME). >Currently I am using only a single long yagi without a rotator. >I am planning to put up an additional 3 long yagi's and am looking for >a rotator that is capable of rotating quite a large array (each yagi is 7 >meters long) in both azimuth and elevation. > >I read somewhere that most of the 'commercial' rotators is not capable of >rotating with an acceptable accuracy for EME. Apparently you need the >rotator to be able to rotate to within 0.5 or 0.25 of a degree (in both >planes). The theory is that drop off is about 1db /deg misalignement so to justify that low noise front end which shaved off 0.1db, you should also point your antennas with equivelent accuracy. > >Does anybody know of a rotator that can do this? >Do you perhaps know of someone doing EME and what is he using for rotation? If you are following an analogue output (eg voltage from a variable resistor that has a weight hanging off theshaft, to get elevation) with an 8 bit DAC, you can only resolve 256 positions. In 90 deg elevation that is about 1/4 degree. If you are using the same system for azimuth you'll only get 1 degree resolution. Most pots aren't any more linear than that. So what they're talking about is what the best of them can get, after a lot of trouble. For what you are doing, I would point it at the moon as best you can and look for the big guns. That 's what I did last year and got W5UN. Joe Mack NA3T . > >All info is welcomed. > >73's >Keith (ZS6TW) > > Potch Univ. Email : Tel: > Potchefstroom itbkl@puknet.puk.ac.za Voice (0148) 992126 > West Transvaal FAX (0148) 992799 > South Africa > > ------------------------------ Date: 25 Oct 1994 15:57:39 GMT From: ftronel@ens-lyon.fr (Frederic Tronel) Subject: double delta loop on 2 meters I've built a double delta loop antenna ,after I've read an article on a french review. The original text has been written by G4ZU Dick. Here's a description of the antenna : (one element) ________ \ / Gain for 1 element :5 Db(d)!!! \ / \ / \/ [] <---- boom /\ / \ / \ /______\ According the author : .On the 10 meters band with 2*2 elements : (Computered) Gain : 10 Db(d) Widthband : 1 Mhz My own experience : .On the the 2 meters band with 2*6 elements : Widthband : 3~4 Mhz (TOS < 1.5) Tos center of the band : 1~1.1 Important gain Fed by two gamma match with 2 capacitors. .polarisation depends of the position of the wire part of the antenna i.e : 6 ________ <------ here it is horizontal \ / 1 \ / 2 \ 8/ \/ [] <---- boom /\ 3 /8 \ 4 / \ /______\ 7 Obviously we have 1=2=3=4 and 7=6 and 8 is an angle .measures: .between elements 0.2 lambda (wave length) .radiator : .1=0.34 lambda .6=0.32 lambda .angle 8 =56 degrees (theorically) ,in practice 70 degrees will be better, in order to stretch the wire part of antenna (I hope it's clear) .reflector : +5% applied to the measures of the radiator .directors : -5% applied to the measures of the last director .feeding : 2 gammas match with 2 capacitors placed on (1 and 3) or (2 and 4). One gamma match is done like this : /\ / \ / \ / \ <- wire / \ / \ / \ / \ / \ / \ /____________________\ | | ----___| |_______| short circuit ---- | | coax capa This figure is done for a simple delta loop ,in the case of a double delta loop, you two gammas : one here _____ another here | | | coax | | For capacitors 10 pF are a maximum ,but they have to be equals. If you have informations about such antenna ,or if you want further info ,my mail: ftronel@ens.ens-lyon.fr 73's from F1SDZ (Fred) ------------------------------ Date: Tue, 25 Oct 1994 13:28:55 GMT From: roberson@HDFS3.UCSD.EDU ( Brad Roberson ) Subject: Needed: J-pole measurements A couple years ago I found an article for a J-pole made of 1/2 inch copper water tubing. The article had the equations for spacings, lengths, and antenna wire placement. If someone could post those measurements I would appreciate it very much. *---------* Applied Computing Devices, Inc. _**_ | RESCUE |_*_ BRAD A. ROERSON IIIIIIIII-|____\ | 95 |---\_ roberson@acd4.acd.com /-------| 91 |< =(O)-------(O)-' Honey Creek Volunteer Fire Department +-(O)-----(O)-+ ------------------------------ Date: 25 Oct 1994 06:08:06 GMT From: garyk9gs@solaria.mil.wi.us (Gary T. Schwartz) Subject: Phased array antennas Jeff Cauhape (cauhape@twg.com) wrote: : Hi, : Can anyone recommend an intro text on phased array : antenna design? Any help would be appreciated. : Jeff Cauhape KB6TDU. ************************************************************************** Hi Jeff, I would recommend getting ON4UN's book: "Low-Band DXing" 2nd edition. It has a lot of info plus many references to Ham Radio, QST articles. Good luck and let us know what you end up building! P.S. The book is available from most dealers and I think the ARRL. 73 Gary K9GS garyk9gs@solaria.sol.net ------------------------------ Date: 24 Oct 1994 23:23:02 -0400 From: sean1916@aol.com (Sean1916) Subject: Racal Radio's In article <38cqbe$q81@mango.aloha.com>, corrigan@aloha.com () writes: Are you interested in selling this radio? if so e-mail me. ------------------------------ Date: 25 Oct 1994 09:05:12 GMT From: moritz@ipers1.e-technik.uni-stuttgart.de () Subject: Re : double delta loop on 2 meters Fred, Since you are reposting this design, some criticism is called for: 1: Although the boom is really short, the elements require a total of about 24 meters of stiff aluninium material, which will not be cheap unless you are fortunate in knowing the right source. 2: It is a homogeneous array, (dimensions and separations of directors are all equal). From homogeneous Yagis it is known that the gain tends to saturate, and all new and optimized designs therefore are inhomogeneous. 3: Although the gain of the 2 ele double delta loop is substantial, I would strongly recomend not to build such a major antenna project as the 6 ele version, unless accurate gain figures are known. May be someone with NEC 2 experience can help there. 73, Moritz DL5UH Disclaimer: The above said does not intend to raise any political, religious ore ethnic issues. ------------------------------ Date: 24 Oct 1994 19:23:33 -0400 From: c002@ns3.CC.Lehigh.EDU (David M. Roseman) Subject: what IS a bevrage antenna? what IS a beverage antenna anyway? and what is it comprized of? LEDs?! thanks David |-----------------------------------------------------------------------| | David Roseman | c002@lehigh.edu | | SysOp of NODE 3 BBS | The Flying HAm - BBS | | Running OBV/2 Software | KBR-9318 - CB | | | N3SQE/SVARC - Ham | | HAmmy in IRC | N3SQE@N3IQD.FN20GO.PA.USA.NA - Packet | |-----------------------------------------------------------------------| ------------------------------ Date: 25 Oct 1994 04:14:25 GMT From: little@iamu.chi.dec.com (Todd Little) Subject: where do I go for local antenna laws In article <1994Oct24.115914.9504@ned.cray.com>, demers@labman.cray.com (Larry DeMers) writes: |>In article jeffp@access3.digex.net (Jeff Poretsky) writes: |>>Hoping for some help: |>> |>>I Don't want to deal with a runaround with my community. |>>Which Municipal office do I contact to find out about antenna |>>laws? |>> |>> |>>Thanks |>> |>>n2top |> |>Contact your local zoning office. They should have the info. You should also check with the inspection services department or whatever the name of the department that deals with building codes enforcement. Some communities cover antenna restrictions (or at least requirements) under their building codes in addition to their zoning codes. Aren't bureaucrats wonderful? 73, Todd N9MWB ------------------------------ End of Ham-Ant Digest V94 #356 ******************************