Build a hanging dipole for 2 metres

Described here is a simple omnidirectional, vertically-polarised dipole for 2 metres (145 MHz). Made from coaxial cable, it can be rolled up and stored in a small container. It may be used as is indoors, or waterproofed for use outside. No extravagant gain claims are made; this dipole has no more gain than any other. However, it should be significantly more effective than the antenna that came with your handheld. The cost of building the project is around five pounds. Allow about 20 minutes to construct and erect the antenna.

A single length of 50 ohm coaxial cable forms both the antenna element and the feedline. The antenna is made by removing a quarter wavelength of outer jacket and bending the braid back along the cable towards the transceiver to form a vertical dipole. This means no metal work or wiring is required (apart from attaching the BNC or PL259 plug).

Parts required

• 3-4m RG58 coaxial cable (not critical - use longer length if height is needed or the operating position is distant from the antenna)
• PL259 or BNC plug (to suit transceiver)
• small metal lug, washer or nut
• tape measure, scissors, small screwdriver, long-nosed pliers, multimeter, fishing line, soldering iron

Construction

• Solder the PL259 or BNC plug to one end of the RG58 cable.
• From the other end of the cable remove 50cm of the black plastic outer covering to expose the braid.
• With a small screwdriver (Phillips head is best) gently part the braid to make a small hole near where it ceases to be covered by the plastic jacket. Aim to make it about 5mm in diameter.
• Use either pliers or a screwdriver to pull the inner conductor out from inside the braid through the hole in the braid (Fig 2c).
• Fold the braid back along the cable towards the plug. Solder the end of the braid to prevent fraying.
• Remove about 5mm insulation from the inner conductor.
• Solder the end of the inner conductor to a small metal lug or nut.
• Thread fishing line through the lug or nut and hang the antenna in its desired position.

Your antenna is now operational. Check for VSWR of 2:1 or lower.

NB: This design could be used for any band as long as each of the elements are a 1/4 wavelength long for the band you want to use.

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