Date: Fri, 19 Nov 93 04:30:31 PST From: Ham-Ant Mailing List and Newsgroup Errors-To: Ham-Ant-Errors@UCSD.Edu Reply-To: Ham-Ant@UCSD.Edu Precedence: Bulk Subject: Ham-Ant Digest V93 #115 To: Ham-Ant Ham-Ant Digest Fri, 19 Nov 93 Volume 93 : Issue 115 Today's Topics: ARRL Handbook - HELP! Compact Quad Discones & Polarization Helical antenna (3 msgs) Inverted V. Tower Guy Anchors Wobulators and Goniometers (2 msgs) 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: 17 Nov 93 16:52:07 GMT From: ogicse!emory!darwin.sura.net!fconvx.ncifcrf.gov!fcs260c!mack@network.ucsd.edu Subject: ARRL Handbook - HELP! To: ham-ant@ucsd.edu In article <2cdevo$6lj@hp-col.col.hp.com> jms@col.hp.com (Mike Stansberry) writes: >RYAN EGELAND (r_egeland@cc.colorado.edu) wrote: >: I'm new to the HAM world, and haven't even bought the ARRL handbook. I've >: heard that this book is definately the best resource for a beginning ham to >: find out about making antennas and matching them with frequencies. I have a >: good physics / math / electronics background, but would just like to find out >: about what HAM radio is all about! Could anyone give me the source for the >: ARRL handbook - I've heard it's around $20, but my Library doesn't have it. >: Thanks in advance, > >: Ryan Egeland > >Since you're in Colorado Springs, try Centennial Electronics on E. Bijou, >just across the street From Montgomery Wards. > >Mike, K0TER > I'd suggest the RSBG books, they're more fo r the technically minded. Joe NA3T mack@ncifcrf.gov ------------------------------ Date: Thu, 18 Nov 1993 08:13:45 GMT From: elroy.jpl.nasa.gov!swrinde!cs.utexas.edu!utnut!nott!cunews!freenet.carleton.ca!Freenet.carleton.ca!aj467@decwrl.dec.com Subject: Compact Quad To: ham-ant@ucsd.edu I am thinking of building a two element 40 mtr quad. I have a space limitation though and am wondering if I can reduce the height to about 20 feet by wrapping the full wave loops twice around the frame, instead of just once. ie two turns @ 19 ft per side for the reflector and two turns of the driven element @ 17 - 18 ft per side for the totals of 152ft for reflector and 140 ft for driven element. How would this affect the F/B and Gain figures? -- Bill VE3NJW Advanced Amateur Packet Address : VE3NJW@VE3KYT.#EON.ON.CAN Freenet Address: aj467@Freenet.Carleton.ca ------------------------------ Date: 12 Nov 1993 13:27:29 -0800 From: overload.lbl.gov!agate!howland.reston.ans.net!europa.eng.gtefsd.com!avdms8.msfc.nasa.gov!sol.ctr.columbia.edu!news.kei.com!ssd.intel.com!chnews!ornews.intel.com!ornews.@dog.ee.lbl.gov Subject: Discones & Polarization To: ham-ant@ucsd.edu In article tomb@lsid.hp.com (Tom Bruhns) writes: >: > >It is my understanding that discones are circularly polarized. >: They're verticals. >Except, of course, for the non-vertically (e.g., horizontally) mounted ones... Wouldn't a Conical Dipole be better in this case? Or is the bandwidth wider with the discone? Why not a vertically polarized conical dipole? It could also be used as a rain gauge. -- zardoz@ornews.intel.com WA7LDV ------------------------------ Date: Mon, 15 Nov 93 13:17:16 CST From: tribune.usask.ca!canopus.cc.umanitoba.ca!mizar.cc.umanitoba.ca!bison!sys6626!inqmind!tmantler@decwrl.dec.com Subject: Helical antenna To: ham-ant@ucsd.edu hello all, I'm planning on building a helical antenna, but I need the formulas for the measurements. Also some tips on construction methods would help. Thanx Tony Mantler, Winnipeg tmantler@inqmind.bison.mb.ca- The Inquiring Mind BBS, Winnipeg, Manitoba 204 668-8845 ------------------------------ Date: 17 Nov 1993 20:38:05 GMT From: elroy.jpl.nasa.gov!news.larc.nasa.gov!arbd0.larc.nasa.gov!zawodny@uunet.uu.net Subject: Helical antenna To: ham-ant@ucsd.edu In article tmantler@inqmind.bison.mb.ca (Tony Mantler) writes: >hello all, > I'm planning on building a helical antenna, but I need the >formulas for the measurements. Also some tips on construction methods >would help. > The helical antenna is very broad banded and very forgiving so construction can be quite easy. The circumference of the helix (length of one turn) is equal to one (free space) wavelength. The pitch of the helix (spacing between turns) can vary between 10 and 20 degrees with 14 degrees being a common value. The 14 degree pitch gives a spacing of about 1/4 wavelength between the turns. The "ground plane" for the helical antenna is usually a disk or screen with a diameter of 3/4 of a wavelength and it may or may not have a rim (making it look like a cakepan) with a height of ~.1 wavelength. The trick part in construction come when doing the impeadance matching. Most of the ones I have built and seen utilize a length of sheet copper soldered to the last eight of a turn on the helix which is then bent to vary the spacing from the groung plane until the desired impedance is obtained. Adding turns to the helix generally dereases beamwidth and increases gain, but only up to a point. When the number of turns gets well above 10 or so, the theoretical beamwidth gets very narrow and the alignment of the turns becomes the limiting factor in the antenna performance. Have fun, -- Joseph M. Zawodny (KO4LW) NASA Langley Research Center Internet: zawodny@arbd0.larc.nasa.gov MS-475, Hampton VA, 23681-0001 Packet: ko4lw@n4hog.va.usa ------------------------------ Date: 17 Nov 93 16:50:14 GMT From: ogicse!emory!darwin.sura.net!fconvx.ncifcrf.gov!fcs260c!mack@network.ucsd.edu Subject: Helical antenna To: ham-ant@ucsd.edu In article tmantler@inqmind.bison.mb.ca (Tony Mantler) writes: >hello all, > I'm planning on building a helical antenna, but I need the >formulas for the measurements. Also some tips on construction methods >would help. > >Thanx > > Tony Mantler, Winnipeg > >tmantler@inqmind.bison.mb.ca- >The Inquiring Mind BBS, Winnipeg, Manitoba 204 668-8845 The formulae etc are in most antenna handbooks (try the RSGB first, and the ARRL if you can't find the RSGB). There are also programs (one called helix I believe that are on BBS's, I'll find it if you e-mail me) to save you looking up tables. There are two main things to know - the bandwidth which is about 2:1 for short helices drops as they get longer - still the bandwidth is enormous compared to any ham band even for long helices. The other is that the impedance is 140ohms which doesn't match anything. You can use a quarter wave transformer, which is narrow band, or put 4 of them together (if you're at UHF or above) or there's atrick using the last 1/4 wave of the helix as a transformer (in RSGB book). Helices tend to be eliptically rather than circularly polarised unless you taper the turns at the furthest end so that sprial in to the axis. Joseph Mack Joe NA3T mack@ncifcrf.gov ------------------------------ Date: 16 Nov 1993 23:01:24 GMT From: elroy.jpl.nasa.gov!usc!cs.utexas.edu!asuvax!ncar!noao!CS.Arizona.EDU!organpipe.uug.arizona.edu!helium!hlester@decwrl.dec.com Subject: Inverted V. To: ham-ant@ucsd.edu Kenneth Opskar wrote: >I'm planning to set up an inverted V, and have heard that the apex angle is >critical. It seems to me that i can't manage more than 80-85 degrees, at least if >the apex angle shall be 0.2 the wavelength above ground. I can manage 110-120 >degrees, but then the feed point will not be more than 27 feet above ground. >I also have heard that the end insulators mustn't get to close to lossy ground. > >At last, the antenna will be surrounded by walls, like streching the feed line >up the corner of a house, and streching the two wires along the walls. The proximity to the walls/houses may have the most (negative) effect on the performance of your antenna, less so the height of the apex and the closeness to ground of the ends. An inverted V "must not" be of an angle less than 90 degrees; I recall 127 degrees is ideal for a 50 ohm match, but I do not think this is awfully critical. I'd recommend the 110-120 degree angle setup, not the 80-85. Make the antenna legs longer than they "should" be so that you'll have some wire to cut off for possible pruning. Thus, two variables are present for matching: pruning the antenna leg lengths (by equal amounts), and varying the apex angle. Howard KE7QJ ------------------------------ Date: Tue, 16 Nov 1993 16:19:45 GMT From: library.ucla.edu!europa.eng.gtefsd.com!howland.reston.ans.net!vixen.cso.uiuc.edu!sdd.hp.com!col.hp.com!fc.hp.com!jayk@network.ucsd.edu Subject: Tower Guy Anchors To: ham-ant@ucsd.edu Gary Coffman (gary@ke4zv.atl.ga.us) wrote: : If you can get access to a cable tension gauge, set the guy tension to : 50-75 pounds depending on temperature, the tower will "grow" in warm : weather so use the higher tension setting then. The guys will loosen in : cold weather as the tower shrinks. : Gary The Rohn catalog says to tension the guys to 10 percent of their rated value (when using the proper size guys they recommend for various towers). I'm no expert on why, but thats what is says. 73, Jay K0GU jayk@fc.hp.com ------------------------------ Date: Mon, 15 Nov 1993 16:06:06 GMT From: unogate!news.service.uci.edu!usc!howland.reston.ans.net!europa.eng.gtefsd.com!gatech!swrinde!cs.utexas.edu!csc.ti.com!tilde.csc.ti.com!cauldron!ra.csc.ti.com!fstop.csc.@mvb.saic.com Subject: Wobulators and Goniometers To: ham-ant@ucsd.edu Regarding goniometers, I remember something from my days in field service on instrument landing systems. Some one of the other normal pieces of airport electronics, the VHF OmniRange (VOR), I think, used something the guys that worked on it called a goniometer as an antenna. The basic idea was that a properly phased signal or set of signals applied to this device would cause an RF beam to sweep through 360 degrees in some specified interval after a omnidirectional burst occurred. By measuring the interval between the arrival of the omni burst and the sweep, one could determine their position relative to the station transmitting the signals. This would seem to fit with Tom's "device to measure angles" definition. I could be all wet on this. It has been nearly 20 years since I worked in that field and I have slept since then. ********************************************* | Steve Brown, WD5HCY | | | sbrown@charon.dseg.ti.com | Simplicate | | wd5hcy@wd5hcy.ampr.org | and add | | [44.28.0.61] | lightness. | | wd5hcy@kf5mg.#dfw.tx.usa.na | | ********************************************* ------------------------------ Date: 16 Nov 1993 13:06:32 GMT From: olivea!inews.intel.com!ilx018-bb.intel.com!ilx049!dbraun@uunet.uu.net Subject: Wobulators and Goniometers To: ham-ant@ucsd.edu In article , tomb@lsid.hp.com (Tom Bruhns) writes: | | |> "Wobulator" (or wobbulator) wasn't in the unabridged Webster's I used ;-) Well, MY Webster's (the really gigantic Merriam-Webster one) does have "wobulator". I was amazed. -- ------------------------------------------------------------------- Doug Braun Intel Israel, Ltd. M/S: IDC1-41 Tel: 011-972-4-655069 dbraun@inside.intel.com ------------------------------ Date: 12 Nov 1993 13:14:51 -0800 From: overload.lbl.gov!agate!usenet.ins.cwru.edu!magnus.acs.ohio-state.edu!math.ohio-state.edu!sol.ctr.columbia.edu!news.kei.com!ssd.intel.com!chnews!ornews.intel.com!ornews.@@dog.ee.lbl.gov To: ham-ant@ucsd.edu References , <2bttse$ol@ornews.intel.com>, s. Subject : Wobulators and Goniometers In article jholly@cup.hp.com (Jim Hollenback) writes: >Jim Garver (zardoz@ornews.intel.com) wrote: >: Sacrilegious plastic 450 ohm line. I was unable to find a real wobulator >: of suitable size, only those dinky ones found in ARC-5 transmitters. > >I know what an ARC-5 transmitter looks like, but pray tell, what is >a wobulator? I may be full of it, but I believe its a sorta link-coupled transformer where the secondary winding is mounted inside the primary on a shaft attached to a knob. Turning the knob will vary the transformer coupling by twisting the secondary windings turns with respect to the primary windings. Its commonly used on shipboard transmitting equipment among other places. There its usually housed in a separate box but may be integrated into the transmitter as in the ARC-5. Why its called a wobulator I don't know execpt to guess its because the secondary wobbles inside the primary. Why is a goniometer called a goniometer? What is a goniometer? A weird antenna gizmo with crossed windings used for direction finding. -- zardoz@ornews.intel.com WA7LDV ------------------------------ End of Ham-Ant Digest V93 #115 ****************************** ******************************