Two Element Phase Vertical Dipole Array

---It fits in a skibag

Needs on 15

• Directional• Easy to set up• No ground plane• Highly portable• Materials mostly available from current

stock • Fair amount of bandwidth 

"Creating" Gain(A measure of the effectiveness of a directional antenna as compared to a standard nondirectional antenna.)

This is how gain is created--by arranging the currents in an antenna so that the fields they radiate sum together in a few directions and cancel elsewhere.

-- ARRL Continuing Education Program

Antennas do not somehow magically create power but simply focus the radiated RF into narrower patterns such that there appears to be more power coming from the antenna in the required direction. -- Marc Dekenah

Phasing, in general

Imaging a tank of water with some sort of vibrating element to generate waves stuck into it. If another vibrating element is stuck into the water operating at the same vibration rate and same intensity, it will generate waves of the same frequency and height (or "amplitude"), but the peaks and valleys of the waves generated by the second vibrating element will not necessarily coincide with those of the first. In other words, they won't have the same "phase".   Greg Goebel, Basic Principles Of Radar 

But, "...two currents are in-phase when they reach their maximum values, in the same direction, at the same instant. "  ARRL Antenna Book.

Phasing

phased array: A group of antennas in which the relative phases of the respective signals feeding the antennas are varied in such a way that the effective radiation  pattern of the array is reinforced in a desired direction and suppressed in undesired directions.

  Federal Standard 1037C,  Telecommunications: Glossary of Telecommunication Terms 

Arrays

A simple directional antenna consists of a linear array of small radiating antenna elements, each fed with identical signals (the same amplitude and phase) from one transmitter. As the total width of the array increases, the central beam becomes narrower. As the number of elements increases, the side lobes become smaller.

Toby Haynes, A Primer on Digital Beamforming

 Or, even simpler:

A phased antenna system consists of two or more active antenna elements, arranged so the electromagnetic fields effectively add in some directions and cancel in other directions. This produces enhanced transmission and reception in the directions where the fields add, and reduces the strength of radiated and received signals in the directions where the fields cancel.

Whatis.com

One element out of phase

180 degrees

Phasing Graphs

 

Some of the ways to phase

 

Blockish Diagram

Feedline can be any length

Rendering

Radiation Pattern

SWR in theory (and in practice, too)

Calculations for the Aluminum

468 / 21.2 = 22.0754717    (468 / 21.2) / 2 = 11.0377358

Both the bottom and top must be little more than eleven feet.  Therefore there must be 1' of overlap between the sections.  1.  Mark it2.  Clamp it3.  Use Penetrox

Gravity should hold most of this together.

Close-up of center Insulator

Alternate guy ring

Delrin Rods

Clamp forelectrical connection

Single Element

Array In Action

Possible other kinds of bases

Ingredients

Tips

• Use high-quality hose clamps• In your “kit” include a 8mm Y-wrench

(sold primarily to bicyclists)• Include some ties to ensure that

coaxes leave insulator at 45 degree angle 

• Wrap all ropes neatly around tent stakes

• Penetrox • Put something on top like a soda

bottle • Take care in drilling holes in project

box. 

Some variants

• Stacked Verticals (i.e. colinear)• “diamond” loop-like thing as used on VP6• More verticals dipoles• The whole thing elevated• Parasitic elements (switchable)• Move verticals to beach•  Hats on low bands

Thanks

Nasra/KB3OLPJohn/N3HBXChris/KB3CS Bill/NG3KDavid/KB3NAI Megan/KB3RGW