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Getting
the biquad antenna parts
The
materials for the biquad are simple: copper wire, printed
circuit board (PCB), copper pipe, coaxial cable and "N"
type connector.
Depending
on your locale you may have to mail order some of these parts.
HAM radio
stores and radio amateur swap meets are great places to
get the stuff. Ebay is also a good place but expect to pay
more because of shipping costs for individual items. I have
ordered biquad kits on Ebay at a price that beats getting
all components separately.
Along
with microwave cable the "N" connector is probably
the hardest piece to find. Special low loss microwave LMR
400 cable is recommended but the length of cable used in the
antenna is so short that any 50 Ohm cable will work just fine.
Tools
Cutting
copper pipe is a slow process unless you have a good metal
saw. Another tool of great importance is the soldering iron.
You will need a lot of heat because of the heat dissipation
in the large metal mass you are trying to soldier. My electric
soldering iron was not working for this at all and I used
a small butane
torch from Radio Shack. I love this tool! It's very versatile
because it doubles as a soldiering iron and there are no cables
dangling.
Drilling
the PCB is very easy but you will need a range of drill bits
to build up the hole size for the copper pipe to fit through.
One type of drill bit I find particularly useful for this
type of work is called step bit [Fig. 1].
Fig. 1 Step bits by Fourman
If
you don't have access to a good vise
you can make a simple hands-free rig out of a short wood board.
Drill a hole just barely tighter than the copper pipe in the
middle of the board. Cut two short board pieces for feet and
nail the board with a hole on top of them [Fig. 2]. This tool
will allow you to jam the copper pipe tight into the wood
and lay the PCB at a perfect 90 degrees angle [Fig. 3]. The
metal pieces will get very hot during soldiering. Wear work
gloves or avoid touching metal while hot.
Fig. 2 Simple biquad assembly bench
Fig. 3 Copper pipe and square PCB on the bench
Once
you are finished building the biquad you may consider placing
it in an enclosure for protection. See the enclosure building
instructions here.
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