Date: Sun, 16 Oct 94 04:30:12 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 #347 To: Ham-Ant Ham-Ant Digest Sun, 16 Oct 94 Volume 94 : Issue 347 Today's Topics: A3 Cushcraft in the attic DISTRIBUTION STATUS Is SWR it? Q: VLF antenna design TV Rabbit Ears for 2m ? 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: Fri, 14 Oct 1994 16:04:12 From: JairoE@aol.com Subject: A3 Cushcraft in the attic I just bought a new house and no antennas are allowed in the area. I have a Cushcraft A3, Does anybody have any experience using this antenna inside the attic? and How can I ground the antenna? Thanks in advance JAE ------------------------------ Date: 15 Oct 94 05:43:05 GMT From: POSTMSTR@GSGMVS.EMIS.HAC.COM (Postmaster) Subject: DISTRIBUTION STATUS SMTPGATE.HAMANT DISTRIBUTION STATUS INFORMATION 10/15/94 05:43 :28 ======================================================================= DISTRIBUTION ID: SMTPGATE.HAMANT.3109 SUBJECT : Ham-Ant Digest V94 #346 DOCUMENT NAME : %%DOCNAME DATE SENT : 10/15/94 TIME SENT: 05:41:00 ======================================================================= YOUR MAIL WAS NOT DELIVERED FOR THE FOLLOWING REASON: SNADS STATUS : 0006 X.400 CODE : %%DIAGCODE INFORMATION : %%SUPPLINFO EXPLANATION : SNADS PERMANENT SERVER ERROR ======================================================================= RECIPIENT : CCMAIL.00A8929 LAST NAME : FIRST NAME : MIDDLE INITIAL : INITIALS : NATIVE NAME : COUNTRY : ADMD : PRMD : ORGANIZATION : ORG UNIT 1 : ORG UNIT 2 : ORG UNIT 3 : ORG UNIT 4 : DDA : TITLE : DESCRIPTION : USERDATA : TELEPHONE : ------------------------------ Date: Fri, 14 Oct 1994 22:09:41 GMT From: gary@ke4zv.atl.ga.us (Gary Coffman) Subject: Is SWR it? In article <37kuvb$ji1@marlin.gulf.net> lester@marlin.gulf.net (Sean Lester) writes: >If you match your antenna imedance with your transmition line and >transmitter, then get your SWR down to < 1.2:1, do I have to worry >about anything else for VHF? I put a couple of loops in my feedline >at the antenna as an RF choke, just in case. But, I'm afraid I may be >missing something. Yes, you're missing several things like gain, radiation pattern, and efficiency. A low VSWR only indicates that the transmission line/load are absorbing the power of the transmitter, not that they are doing anything useful with it. A broad flat VSWR curve *may* indicate a very lossy antenna system. Your antenna system may have enough resistive losses that most of your power is actually being turned to heat instead of useful radiation. Your antenna pattern may be such that most of the power that is radiated is directed upward or downward, or otherwise in a non-useful direction. Your antenna may exhibit negative "gain" in the desired direction, etc. All that can exist with a low VSWR reading. So yes, there are lots of things other than VSWR to worry about. Hams tend to be obsessed with VSWR because instruments to measure it are so widely, and cheaply, available. Far more important are the field strength and pattern produced by the antenna. Gary -- Gary Coffman KE4ZV | You make it, | gatech!wa4mei!ke4zv!gary Destructive Testing Systems | we break it. | emory!kd4nc!ke4zv!gary 534 Shannon Way | Guaranteed! | gary@ke4zv.atl.ga.us Lawrenceville, GA 30244 | | ------------------------------ Date: 15 Oct 1994 14:23:39 GMT From: vhansen@ipfy.bau-verm.uni-karlsruhe.de (Wolfgang von Hansen) Subject: Q: VLF antenna design Hi everybody! First of all I want to apologize for my bad english regarding the technical terms--but being a beginner to antenna design implies not knowing all the words correctly. I need some information on how to build a VLF antenna. It shall receive signals at 10-14kHz with an omnidirectional characteristic. It should also be quite small [<=1ft] in size. Currently I am thinking of two ferrite bars (?) which are arranged orthogonally. What I need to know is how to calculate the resonant circuit. I also need infos on how to build a simple amplifier and connect the antenna to it. A transformation of the signal to other frequencies is not necessary. Thaks in advance, Wolfgang -- vhansen@ipf.bau-verm.uni-karlsruhe.de | Gurus use `cat >a.out' instead of gcc float o=0.075,h=1.5,T,r,O,l,I;int _,L=80,s=3200;main(){for(;s%L|| (h-=o,T= -2),s;4 -(r=O*O)<(l=I*I)|++ _==L&&putchar(*((--s%L?_ <373266$30m9@info2.rus.uni-stuttgart.de>, <682014245wnr@ifwtech.demon.co.uk> Subject: VHF/UHF DX book In article <682014245wnr@ifwtech.demon.co.uk> G3SEK@ifwtech.demon.co.uk writes: >In article: <1994Oct7.223912.2532@arrl.org> zlau@arrl.org (Zack Lau (KH6CP)) writes: >> > from Ian G3SEK | Editor, _The_VHF/UHF_DX_Book_ > Abingdon, England | > g3sek@ifwtech.demon.co.uk | "In Practice" columnist for RadCom (RSGB) > Thank you for the VHF/UHF DX book, which is the best ham book I have read in probably 15-20 years. Very inspiring. I got mine by chance. WHen I tried to get another for a friend I couldn't find it anywhere in the US, for love or money. THe ARRL doesn't have it, major ham sotres don't have it, minor ham stores don't have it. There isn't an address to get it from in the front cover. How do I get one, if I only have US$? (getting a bank draft is a minor pain and costs $5.00). Joe Mack NA3T ------------------------------ Date: 15 Oct 1994 07:21:50 -0400 From: beau@enterprise.america.com (J. E. Winburn) References<36i2i6$jja@enterprise.america.com> <37c73c$1nl@jericho.mc.com>, <37h46n$qn6@hplvec.lvld.hp.com> Subject: Re: Tiger Tail (HT antenna) Scott Turner (scott@lvld.hp.com) wrote: : Bob Levine (levine@mc.com) wrote: : : I discovered that in the plane of the HT (my FT530), the signal strength : : is greatly increased with the TT.(>2x) The signal strength directly : : above the HT goes way down. The TT seeems to increase the lobes : : in the horizontal plane and reduce the amount of energy going : : vertical. I did these tests the best I could with the HT in : : a plastic holder and keyed up from about 5 feet away with a : : speaker mic so I would interfere as little as possible. : Bob, I would respecfully submit that your test is a bit flawed. For : normal usage, you *are* part of the antenna system on an HT. Performing : the test with your body away from the antenna won't give you realistic : results. : Some time ago, a friend was playing around with a network analyzer and : decided to look at his 2 meter HT antenna. He was somewhat surprised to : find that it appeared to be resonant outside the 2 meter band. He then : moved his head next to the antenna and tried again. You guessed it. : The antenna was now nicely resonant inside the band. : My guess is that your body's proximity to the antenna will have about as : much positive affect as the TT does. In other words, I remain sceptical. Scott, I have run test on the tiger tail myself and firmly agree with you. Running the test without the body in close proximity is unrealistic. When the tigertail is tested with the HT close to the body there is NO noticable change in the signal transmitted with or without the TT. The received signal isn't really considered as the HT will be able to hear signals that it cant reach unless it is another HT. Beau ------------------------------ Date: 15 Oct 1994 16:46:14 GMT From: little@iamu.chi.dec.com (Todd Little) References<37idkr$78t@mozo.cc.purdue.edu> <37kvvb$cn2@nntpd.lkg.dec.com>, <37lmsm$2rca@info2.rus.uni-stuttgart.de> Reply-To: little@iamu.chi.dec.com (Todd Little) Subject: Re: 2m quad construction - help! In article <37lmsm$2rca@info2.rus.uni-stuttgart.de>, moritz@ipers1.e-technik.uni-stuttgart.de () writes: |>>That quad should give around 10 dBi |> |>Todd, |> |>Is that all? I know a design for a 7 ele yagi that gives an extra |>two dB for the same amount of material and is also pretty wide band |>and forgiving. The added advantage is, that it is fed ba a folded |>dipole with a propper balun. |> |>So the 4 ele VHF quad seems to be easy to build but doesnt work too well. Well I don't know of any other 1/2 wavelength antennas that give that kind of gain. A 7 element yagi is going to twice as long. And for doubling the length it only gives 2 dB more gain? ;-) 73, Todd N9MWB ------------------------------ Date: 15 Oct 1994 16:42:46 GMT From: little@iamu.chi.dec.com (Todd Little) References<36q6d6$s60$1@mhade.production.compuserve.com> , <5O0XpBk.rutledges@delphi.com> Reply-To: little@iamu.chi.dec.com (Todd Little) Subject: Re: Antennas are prohibited ...!!!!!!.. In article <5O0XpBk.rutledges@delphi.com>, Priscilla Rutledge writes: |>Just to provide the Devil's advocate, it is not just a pretty looking |>neighborhood that we, your neighbors, want. As you may have noticed, |>most folks in late 20th century America make decisions based on perception, |>rather than real risk. I personally don't mind even a 20m antenna if |>you don't let it get rusty and tumbledown. What happens, though, is that |>when I go to sell my house (and since so many of the people in my |>association are military, 10-20% of them are on the market at any given time) |>the eco-wimps ask worried questions about the "invisible rays" zapping |>through the children's little bodies. If they heard you use the phrase |>"Radiation Pattern" they probably wouldn't move into the same county. |>This foolishness can trim $10-15K off my final selling price. True, it This may be your perception, but there are no studies that I'm aware of that support that supposition. In fact, there are studies to the contrary, and in addition, if it was $10-15K, there would be something in an appraisers handbook about it, but there isn't. |>is neither my foolishness nor yours, but I reserve the right to |>from whatever "liberty" anyone chooses to take with it! Taking away the rights of others in the pursuit of liberty sounds just a little bogus. 73, Todd N9MWB From ham ------------------------------ End of Ham-Ant Digest V94 #347 ******************************