sideways V antenna?
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Fellow Elecrafters,
There's lots of stuff in the antenna literature about inverted V antennas, i.e., where the feedpoint is higher than the ends. But I can't find anything on dipoles and such in which the ends are not in the same vertical plane as the center. I'm thinking of putting up a stealth antenna that would be an OCF dipole with the feedpoint at the peak of my roof, and the ends extending toward two trees alongside the house. I've taken some measurements and calculated the angle between the legs as being about 97 degrees - but of course in the horizontal plane, not the vertical plane like an inverted V. I'd feed it with ladder line and my good ole Johnson Viking Matchbox, so I'm not worried about effects on feedpoint impedance. I imagine it would exhibit some directionality, probably toward the open side of the V ? Anyone see any major pitfalls with this approach?? 73 Ray K2HYD KX-1 # 608 _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Real world implementations of antennas are constrained by the type and location of support structures that are on site. That said, put it up and see how it works. Any antenna is better than none. Bob K3YT _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Albers-3
Albers wrote:
> Anyone see any major pitfalls with this approach?? Tom, N6BT (founder of Force 12) has been known to say, "Everything will radiate." He often shows pictures of his "Illuminator" antennas to prove it. One is a light bulb on a post fed with coax and a current balun at the socket. He's actually worked a surprising amount of DX on it. He also has the "Phased Illuminator," three bulbs in a Vee arrangement with the power divided between them. My main antenna for the low bands is a non-resonant inverted vee about 70' at the apex, about 155ft on each leg, with the legs ending just a bit over head height, and a central angle of about 120 deg. It opens to the east. I adjusted the leg lengths to give tractable impedances at the feed point on 30 - 160, and a section of 450 ohm ladder line (length calculated using N6BV's TLW that comes with the ARRL Antenna Book 20th ed) feeding a 4:1 DX Engineering balun near the bottom of the tower w/ coax to the house. It is pretty much omnidirectional on 40 and below, and a cloud warmer on 80 and 160. The pattern gets pretty goofy above 30m. My guess is that your arrangement may exhibit similar characteristics, but then, antennas can be magic. Stick it into EZNEC and see? Fred K6DGW Auburn CA CM98lw Fred K6DGW Auburn CA CM98lw _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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If I recall correctly, John Heys' (G3BDR) Practical Wire Antennas published
by RSGB has a discussion on the Vee Beam (horizontal Vee, twin fed vertical element) antenna. As I recall it was a practical wire antenna with directivity in some bands. ;) I think if you find Jimmy Hoffa, you will find my copy of the book, as I can never find it when I need it. 73, Gil NN4CW _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Albers-3
I've used a center fed antenna like that with good results. The same rule
apples as applies to an Inverted V: keep the angle >90 degrees to avoid excessive signal cancellation. Feeding it off center means your "feed line" is not just a transmission line: it's another radiating element in the antenna. Since the load is unbalanced, the currents will be unbalanced, no matter what you do at the rig end with baluns, etc. So be sure your feedline runs as short a distance as practical near the house, through walls, etc. You didn't say how long it'll be, but at frequencies where the legs get to be a couple of wavelengths long or more it'll start to show directivity in the direction of the open angle of the V. Ron AC7AC -----Original Message----- Fellow Elecrafters, There's lots of stuff in the antenna literature about inverted V antennas, i.e., where the feedpoint is higher than the ends. But I can't find anything on dipoles and such in which the ends are not in the same vertical plane as the center. I'm thinking of putting up a stealth antenna that would be an OCF dipole with the feedpoint at the peak of my roof, and the ends extending toward two trees alongside the house. I've taken some measurements and calculated the angle between the legs as being about 97 degrees - but of course in the horizontal plane, not the vertical plane like an inverted V. I'd feed it with ladder line and my good ole Johnson Viking Matchbox, so I'm not worried about effects on feedpoint impedance. I imagine it would exhibit some directionality, probably toward the open side of the V ? Anyone see any major pitfalls with this approach?? 73 Ray K2HYD KX-1 # 608 _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Albers-3
My group usually puts up a V antenna for 80 and 40 on field day and
makes quite a few contacts on it each time. It works and is fairly directional. We feed it with ladder line as I recall and use a balun. The angle between the legs was around 60 degrees, I'm not sure what a 97 degree antenna would do. Maybe you could get somebody to model it on elnec or similar. ----Dave VE7HP On Sat, Dec 09, 2006 at 04:30:11PM -0500, Albers wrote: > Fellow Elecrafters, > > There's lots of stuff in the antenna literature about inverted V antennas, i.e., where the feedpoint is higher than the ends. But I can't find anything on dipoles and such in which the ends are not in the same vertical plane as the center. > > I'm thinking of putting up a stealth antenna that would be an OCF dipole with the feedpoint at the peak of my roof, and the ends extending toward two trees alongside the house. I've taken some measurements and calculated the angle between the legs as being about 97 degrees - but of course in the horizontal plane, not the vertical plane like an inverted V. I'd feed it with ladder line and my good ole Johnson Viking Matchbox, so I'm not worried about effects on feedpoint impedance. I imagine it would exhibit some directionality, probably toward the open side of the V ? > > Anyone see any major pitfalls with this approach?? > > 73 > Ray K2HYD > KX-1 # 608 > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com -- David Dawson The greatest dangers to liberty lurk in insidious encroachment by men of zeal, well-meaning but without understanding. -- Justice Louis D. Brandeis _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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L.B. Cebik calls this configuration a "quadrant" antenna when the angle
is 90 degrees, and provides some information (patterns and feed impedance) at http://www.cebik.com/gup/gup37.html Jack K8ZOA www.cliftonlaboratories.com home of the Z90 >> Fellow Elecrafters, >> >> There's lots of stuff in the antenna literature about inverted V antennas, i.e., where the feedpoint is higher than the ends. But I can't find anything on dipoles and such in which the ends are not in the same vertical plane as the center. >> >> I'm thinking of putting up a stealth antenna that would be an OCF dipole with the feedpoint at the peak of my roof, and the ends extending toward two trees alongside the house. I've taken some measurements and calculated the angle between the legs as being about 97 degrees - but of course in the horizontal plane, not the vertical plane like an inverted V. I'd feed it with ladder line and my good ole Johnson Viking Matchbox, so I'm not worried about effects on feedpoint impedance. I imagine it would exhibit some directionality, probably toward the open side of the V ? >> >> Anyone see any major pitfalls with this approach?? >> >> > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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