The Super J Pole antenna is a co-linear vertical consisting of a number of half wave length vertical elements separated with half-wave length stubs (Tuning stub) feed with a folded matching stub. The sub doesn’t receive or radiate any energy; it is simply a way of picking off the desired feed impedance.

Additional half wave length section can be added with addition of a half wave length tuning section (Tuning stub). The addition of half vertical elements could be added indefinitely, subject to reality of diminishing returns. This arrangement can be applied practically and usefully on bands within the VHF and UHF spectrum. The use of the J pole feed arrangement creates an antenna that is relatively ground independent compared to many other designs.

DIAGRAM OF THE SUPER J-POLE
Frequency: 435Mhz
Polarisation: Vertical
(A) Main element: 502mm (0.75 Wavelength x 300/f x k)
(B) Matching stub: 167mm (0.25 Wavelength x 300/f x k)
(C) Additional section 334mm (0.50 Wavelength x 300/f x k)
(D) Tuning stub: 334mm (0.50 Wavelength x 300/f x k)
(E) Feed point: Approximately 10 – 30mm from the bottom.

Practical construction
Construction is very simple. After determining the various element lengths, mark them out accordingly on a continuous length of copper wire and bend to achieve the antenna shape. The tuning section that separating the additional half wave length elements can be bent around to form a semicircle (see photos). Tape the wire formed antenna to a suitable length of dowel or fibreglass rod for stability.

After successfully impedance matching the coax feed point with a VSWR meter the antenna can be mounted inside a suitable length of conduit to protect the antenna from the effects of weathering.

It is recommended that the coax be attached through some sort of feed line choke arrangement to mitigate possible common mode currents in the transmission line.