From owner-qrp-l@Lehigh.EDU Sat Sep 6 09:41:52 1997 Received: from fidoii.CC.lehigh.EDU (fidoii.CC.lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.8.5/8.8.5) with ESMTP id JAA01785 for ; Sat, 6 Sep 1997 09:41:51 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.Lehigh.EDU with SMTP id <35327-23028>; Sat, 6 Sep 1997 09:41:16 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.Lehigh.EDU with ESMTP id <35267-24312>; Sat, 6 Sep 1997 09:40:16 -0400 Received: from x3.boston.juno.com (x3.boston.juno.com [205.231.100.22]) by nss2.CC.Lehigh.EDU (8.8.5/8.8.5) with ESMTP id JAA40754 for ; Sat, 6 Sep 1997 09:40:02 -0400 Received: (from wb2vuo@juno.com) by x3.boston.juno.com (queuemail) id J\Q11574; Sat, 06 Sep 1997 09:36:07 EDT Message-Id: <19970906.093519.2127.0.wb2vuo@juno.com> Date: Sat, 06 Sep 1997 09:36:07 EDT Reply-To: wb2vuo@juno.com Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: wb2vuo@juno.com (William K Hibbert) To: "Low Power Amateur Radio Discussion" Subject: Vee Beams for HF/VHF X-To: aamos@gic.gi.com, qrp-l@Lehigh.EDU, n2tuk@frontiernet.net, cg091@freenet.buffalo.edu, EVMAN@ix.netcom.com, bobkowa@netacc.net, billy@frontiernet.net, djw@dos.nortel.com, wfking@kodak.com, kg2f@frontiernet.net, wb8ygg@juno.com, rindiano@rpa.net, duanekf2jc@aol.com, kf2xc@frontiernet.net, X-Mailer: Juno 1.38 X-Juno-Line-Breaks: 0-138 X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO Vee Beams The Vee Beam is one of the earliest, and simplest directional arrays in radio. Basically, a Vee Beam is a pair of long wires (1-wave or greater), aligned in such a way that the major lobes (points of greatest radiation) combine additively producing a sharper beam pattern, and greater gain. The gain of a Vee Beam, according to the ARRL Handbook, 1947 edition, "increases with the length of the wires, but is not exactly twice the gain for a single long wire..." As an example, the Handbook states that the gain of a Vee Beam, 8- waves per leg would be around 12 dB whereas doubling the gain of a single 8-wave longwire would result in approximately 9 dB. This "extra" gain is due to mutual coupling between the wires. The directional pattern for a Vee Beam is bidirectional (no Front-Back ratio), with the strongest lobe along the bisector of the included angle. As the leg length increases, the included angle (V in the drawing) decreases. The antenna is fed with open-wire, ladder line, twin lead or other balanced lines, and the longer arrays show very good multi-band characteristics. Let's say that you wanted to cover the 20 thru 10 Meter bands, including the 17 and 12 Meter bands. Due to the broadbanded characteristics, you could design a Vee Beam for the center of this range, (15 Meters), and tune it to all the bands. Your wave angle would be higher on the lower bands, and the beamwidth a bit narrow on the upper bands, but you would get reasonable gain and directivity thru the entire range. A good example, listed in the ARRL Antenna Book for decades, would be a 3-wave Vee Beam for 15 Meters. The leg length would be 135 feet for 21.2 MHz. This is 2 waves on 20 Meters and 4 waves on 10 Meters (2.5 waves on 17 M and 3.5 waves on 12 M). The gain would be approximately 6 dB on 15 Meters, 5 dB on 20 Meters and 6.5 dB on 10 Meters. A fair gain comparison is a 2-element yagi. So, the gain of the Vee Beam would be in line with a 2-element tri-bander, but on 5 bands, and at a much reduced cost. The included angle for the 3- wave Vee Beam is 60-degrees, so 3 supports would be required, falling on the corners of an equilateral triangle with sides of 140 feet. This is about the space needed for a 1-wave loop for 160 Meters. Here's a "drawing" of the Vee Beam: b / / / / / / / / / a./ \ Feed at points ac. L = ab c. V ab = cd; V = Included angle \ / \ \ \ \ \ \ \ \ \d The included angle "V" decreases as the leg length "L" increases. Here's a chart with Included angle, base on wavelengths, and (very) approximate gains: Waves "V" Gain (App'x) 1 110-degrees 3.5 dB 2 71-degrees 5.0 dB 3 60-degrees 6.0 dB 4 52-degrees 7.0 dB 5 45-degrees 8.0 dB 6 40-degrees 9.5 dB 7 37-degrees 10.5 dB 8 35-degrees 12.0 dB This is not to say that you can't go past 8-waves for a leg length, but that's as long as most hams can handle in the HF spectrum, or even the low VHF spectrum. 8-waves on 6 Meters is about 160 feet, and is almost 65 feet even on 2 Meters. With our 3-wave, 15 Meter design, one can make it into a steered all-bander by putting up a total of 4 wires, spaced 60 degrees and selecting the desired two for the band of interest. It would look something like this: d e \ / \ / \ / \ / -----------O---------- a b c With line ac running from West to East, you can steer it on 20 - 10 by selecting ab and bd, bd and be or be and bc, giving you 3 different bi-directional patterns, 60 degrees apart. On 40 and 30 Meters, you can select ab and be or bd and bc for two bi-directional patterns 120 degrees apart, and on 160 and 80 Meters you can select ab and bc for a "dipole". By feeding with a 4-wire balanced line, you can select the appropriate wires in the shack, or with a relay box at the base of the pole ("O"), they can be switched remotely. This array would require 5 poles and would take up 3/4-acre, quite a bit of real estate! Not for the City Lot, unless you have VERY understanding neighbors! An old idea, but my 10 -Meter Vee Beam plays really well. Give is a try if you have the room... 72/73, Keith, WB2VUO, QRP-L #582, scQRP 40, AR QRP #68, 100% QRP Tech Specialist (ARRL/WNY), ARRL Life Member, Trustee, NQ2RP/B 10 Mtr QRP Beacon (125 mW @ 28.287 MHz) "In the Depths of the Great Bergen (NY) Swamp...FN13ac" Packet - wb2vuo@w2im.#wny.ny.usa.noam *** Email - wb2vuo@juno.com SnailMail - CBA *** Phone - 716.494.1239 "My Night Light runs more power than my Rig!!!"