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What About the "Slim Jim" Antenna ?
The Slim Jim Antenna
http://www.hamuniverse.com/slimjim.html The Slim Jim is a Vertically Polarized Omni-Directional End-Fed Antenna having considerable gain and this is concentrated almost parallel to ground toward the horizon rather than skyward making it more efficient than a ground plane type antenna by about 50 percent better. http://www.hamuniverse.com/2meter300ohmslimjim.html Due to it's SLIM {Very Thin Shape} used in it's Design, there is very little wind loading. It is fed with 50 ohm coax. http://www.ee.washington.edu/circuit...ntennas/slim_j It uses a 'J' type Matching Stub (J Integrated Matching = JIM), http://www.pcs-electronics.com/en/gu...p?sub=antennas Hense the name SLIM JIM. http://en.wikipedia.org/wiki/Slim_Jim_(antenna) Credit for the original design goes to F.C. Judd [G2BCX]. http://www.ee.washington.edu/circuit...ntennas/slim_j How to make a Weatherproof Vertically Polarised Omni-Directional Aerial http://www.irational.org/sic/radio/omni-aerial.html Choosing the Correct Antenna http://www.marcspages.co.uk/tech/antchose.htm Marc's Technical Pages http://www.marcspages.co.uk/tech/index.htm So could I make one of these Slim Jim Antennas for the Shortwave 49 Meter Band ? ? ? and just how Thin-and-Tall would it be ? ? ? What About the "Slim Jim" Antenna ? http://groups.yahoo.com/group/Shortw...a/message/9180 obtw - too fat to be called 'slim' and my name ain't 'jim' :o) a- iane ~ RHF |
What About the "Slim Jim" Antenna ?
On 22 Apr 2006 11:46:13 -0700, "RHF"
wrote: The Slim Jim Antenna http://www.hamuniverse.com/slimjim.html The Slim Jim is a Vertically Polarized Omni-Directional End-Fed Antenna having considerable gain and this is concentrated almost parallel to ground toward the horizon rather than skyward making it more efficient than a ground plane type antenna by about 50 percent better. http://www.hamuniverse.com/2meter300ohmslimjim.html Due to it's SLIM {Very Thin Shape} used in it's Design, there is very little wind loading. It is fed with 50 ohm coax. http://www.ee.washington.edu/circuit...ntennas/slim_j It uses a 'J' type Matching Stub (J Integrated Matching = JIM), http://www.pcs-electronics.com/en/gu...p?sub=antennas Hense the name SLIM JIM. http://en.wikipedia.org/wiki/Slim_Jim_(antenna) Credit for the original design goes to F.C. Judd [G2BCX]. http://www.ee.washington.edu/circuit...ntennas/slim_j How to make a Weatherproof Vertically Polarised Omni-Directional Aerial http://www.irational.org/sic/radio/omni-aerial.html Choosing the Correct Antenna http://www.marcspages.co.uk/tech/antchose.htm Marc's Technical Pages http://www.marcspages.co.uk/tech/index.htm So could I make one of these Slim Jim Antennas for the Shortwave 49 Meter Band ? ? ? and just how Thin-and-Tall would it be ? ? ? What About the "Slim Jim" Antenna ? http://groups.yahoo.com/group/Shortw...a/message/9180 obtw - too fat to be called 'slim' and my name ain't 'jim' :o) a- iane ~ RHF . . The Slim Jim is another name for a J-Pole from everything I read about it. This is a 1/2 wave antenna over a 1/4 wave matching section so your 49 meter band antenna would be rather tall (about 37 meters). Sure, you could make it ......... would be interested to see your plans for installing it 8-} Howard |
What About the "Slim Jim" Antenna ?
wrote in message ... On 22 Apr 2006 11:46:13 -0700, "RHF" wrote: The Slim Jim Antenna http://www.hamuniverse.com/slimjim.html [snip] So could I make one of these Slim Jim Antennas for the Shortwave 49 Meter Band ? ? ? and just how Thin-and-Tall would it be ? ? ? ~ RHF . . The Slim Jim is another name for a J-Pole from everything I read about it. This is a 1/2 wave antenna over a 1/4 wave matching section so your 49 meter band antenna would be rather tall (about 37 meters). Sure, you could make it ......... would be interested to see your plans for installing it 8-} Howard With the base another 1/4 wave above ground, lo and behold the top of the Slim Jim for the 49 m band would be ==== 49 metres above ground! How slim? Probably transmission line theory here so the dimension is independent of the wavelength. You could probably use 300 ohm twin lead if it wouldn't break under its own weight. Tom |
What About the "Slim Jim" Antenna ?
Dale [W4OP] - Most 'xyz' dB Gain claims are relative.
Now take this classic Paper Clip it has an 'xyz' dB Gain over the common Paper Staple . . . As a matter of fact Two Paper Clips can be used to form a Multi-Band 'Folded' Dipole Antenna. One Paper Clip when thoroughly straighten-out can be used as a Full-Wave Horizontal Wire Antenna -OR- That same Paper Clip when thoroughly straighten-out can be used as a Quarter-Wave Vertical Wire Antenna Then again a Bent Paper Clip could be used as an Inverted "L" Antenna -or- an End-Fed Inverted "V". Same basic Paper Clip - simply different applications. well i am feeling a little bent out of shape right now cause in this vertual-paper-less society my paper clips are going the way of buggy whips - iane ~ RHF http://en.wikipedia.org/wiki/Buggy_whip |
What About the "Slim Jim" Antenna ?
On 22 Apr 2006 19:59:17 -0700, "RHF"
wrote: Dale [W4OP], "Since the vertical angle of radiation is so narrow, about 8 degrees toward the horizon, it usually out performs 5/8 wave or groundplane type construction due to their much higher angle of radiation. It is estimated that the Slim Jim has about 6dB gain over a 5/8 wave antenna due to the extreme low angle of radiation." "Editor's Note: There are many gain figures quoted for this antenna and also various descriptions of the actual type of antenna on various websites. Some have even stated that, "In fact I found it outperformed a 1/2wave over 1/2wave over 1/2wave colinea" For many of the design applications as a Transmitting Antenna in the 2-3 Meter range; and a receiving Antenna for the FM Band. This Slim Jim Antenna is effectively a small space Antenna that performs well for it's size and when compared to the greater space requirements of other Antennas. iane ~ RHF . . . . . RHF, This is what is claimed on the website though it is indeed not a true representation of how the antenna performs. They perform no better and no worse than any other half-wave antenna, besides look at how they phrase it "estimated 6dB gain over...." which says that is not calculated, tested or proven. If somebody built a slim-jim (j-pole) that outperformed a colinear with multiple half-wave sections I'd look at how each antenna was installed (height, clear of buildings etc) the type of cable used (well we used hard-line with the slim-jim and 200 feet of RG-174 with the colinear) and wether or not that colinear was properly constructed tuned. Hey, I'm not trying to rain on your parade or be the guy who has to tell you that Santa Claus & The Tooth Fairy or the Easter Bunny don't really exist - but in the end the slim-jim/j-pole just doesn't perform as claimed on the website you have visited. Howard |
What About the "Slim Jim" Antenna ?
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What About the "Slim Jim" Antenna ?
On 22 Apr 2006 11:46:13 -0700, "RHF"
wrote: excerpted This looks like what hams call a J-pole antenna. J-poles are popular on the VHF and UHF bands. There's not much use of them on the HF bands because they would be way, way huge -- your 49 meter version would be about the size of a telephone pole. Rhf, ya really oughtta go to Amazon.com and pick up a used copy of the ARRL Antenna Book; David's advice was right on. bob k5qwg |
What About the "Slim Jim" Antenna ?
Them J-Pole Antennas are supposed to be good,Noc war,Tiem La?
google,Wabash Cannonball Midi Ladies and Gentlemen,Boys and Girls,,, crank that puter bolume wideeeee open.Enjoy. cuhulin |
What About the "Slim Jim" Antenna ?
I own a few slim jim auto car door lock picks thingy.(they look sort of
like extra long strange lookin hacksaw blades) I am not a car thief dude though. cuhulin |
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