Page 36 May June 2014 TCA

Building The Slap Shot: A Hockey Stick Satellite Antenna

Christopher Friesen, CET, VE4CWF
2013 began with the National Hockey
League (NHL) in a labour lockout and,
while most Canadians were lamenting the
loss of their favourite winter sport, I was
not. I was busy building a portable
antenna for satellite operation, one that
would shoot the fve watts from my
handheld transceiver into the fve-hole of
SO-50. To score that goal I needed to
build an antenna that was lightweight and
ergonomic and able to stand up to the
extremely cold temperatures of my
northern climate. The “Slap Shot” was the Figure 1: Cross-section of a half-folded dipole driven element.
result. A portable, cross-polarized VHF/UHF
antenna, designed specifcally for working and is workable with simple hand tools. own so I inserted tubular aluminum,
Low Earth Orbit (LEO) Satellites, using a Cross sectional dimensions of 1 1/8" x ¾" held in place with stainless steel hose
plastic foor hockey stick for the boom. provide the perfect spacing for the folded clamps, to provide the correct length and
dipole design and, at a price of $5.49, well some adjustability. The 2 metre driven
DESIGN PARAMETERS within the budget of the thriftiest Amateur. element was built from one-half of a VHF
The antenna itself is not original. I used The blade of the hockey stick provides a folded dipole so there was no need to
the “Cheap Yagi” dimensions found on convenient point to rest the antenna at the create a bend in the aluminum. If you are
Kent Britain’s, WA5VJB, website. His hip, providing a pivot point to rapidly unable to fnd a similar antenna for use in
design and construction methods are change polarity while supporting the your project, you can build a gamma-
readily available as a PDF download from antenna with only one hand. matched driven element, or use brass
his website. I chose to build the 2 metre CONSTRUCTION rods for the 2 metre elements.
portion with three elements and the 70 Mark the Boom and Drill all Necessary Holes
centimetre portion with 5 elements. Build the 70 cm Elements
Britain’s design uses half-folded dipoles The 70 cm elements were made using The length of hockey stick will affect the
for the driven elements. This design is #10 AWG bare copper wire originally used size of the fnished antenna so choose
easy to construct and easy to feed with to make decorative garden ornaments. element quantity and spacing with that in
coax. The shape of the driven element is mind. Remove the blade from the hockey
shown in Figure 1 and the element Any stiff wire, rod or small diameter tube stick and, using the design dimensions,
lengths and spacing I used are shown in can be used for these elements provided mark it with the locations of the elements.
the Tables below. Other than the hockey it is long enough and pliable enough to Drill appropriately sized holes; this is best
stick boom, the Slap Shot is a junkbox form the half-dipole on the driven element. done with a drill press as it ensures the
antenna. For my prototype, the elements I used a broomstick to form a one-inch holes through the boom will be perfectly
and mounting hardware were all derived radius in the wire. aligned. Hand drills will also produce
from salvaged parts. Build the 2 metre Elements acceptable results.
WHY A HOCKEY STICK? The 2 metre elements were built using Install the 70 cm Elements
Floor hockey sticks have several advantages salvaged parts from old TV antennas. The 70 cm elements can be pushed through
for antenna construction. They are made Figure 2 shows the hockey stick boom laid the holes, centred and held in place with
from rectangular, tubular plastic which out next to salvaged elements and the adhesive of your choice. I used hot
provides nice fat surfaces for mounting mounting hardware, along with my glue, but thermal cycling from bringing the
antenna elements. The plastic provides prototype UHF receiving antenna built on antenna outside in winter, then back
an insulated lightweight boom, accepts a wooden boom. The TV antenna inside, causes the elements to expand
wood screws without requiring pre-drilling elements were not long enough on their and contract and break free from the glue.
ELEMENT DIMENSIONS

2 metre Dimensions
Element Refector Driven (L) Director
Length 40.5" (1029 mm) 38.5" (978 mm) 36.5" (927 mm)
Spacing 0.0 8.5" (216 mm) 19.75" (502 mm)

70 CM DIMENSIONS

Element Refector Driven (L) Director 1 Director 2 Director 3
Length 13.5" (343 mm) 13.0" (330 mm) 12.5" (318 mm) 12.25" (311 mm) 11.75" (298 mm)
Spacing 0.0 2.5” (64 mm) 5.25” (133 mm) 12.0" (305 mm) 18.5" (470 mm)

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