Pirate Nation Radio - Amplified Dipole Antenna
Description: Hello home builders, this time we build an Amplified Dipole Antenna.
This design is a 1 stage amplifier that has about 12db of gain and includes a low pass filter
to reduce the harmonic content. This amplifier is suitable for an input of 25 to 100 MW
depending on the length of the feed line. In this setup we used 25' of RG-6 and approx rf input of 50MW
for an output at the antenna of about 160-175 MW. The transistor is a NTE346.
The dc voltage is fed through the cable to the Amplified Dipole Antenna and is about 18 volts
being provided from a standard power inserter, typically used for cable or sattelite tv line amplifiers.
PCB ready for parts placement Construction: The unit is constructed with copper clad board, a 2.5" x .75" piece is used as the construction surface. I used a dremel tool to remove the copper between the traces (you could make a conventional pcb also). All the resistors are 1/4 watt type and use 22 awg enamel wire for the two coils. Use type 43 material for the ferite bead. I used 75 ohm cable and F type connectors because that what the power inserter used and they are cheaper. The enclosure is short length of 3/4" schedule 40 PVC pipe and a pair of end caps. A small slot on each side allow the the dipole wire leads to exit the enclosure. Drill a hole for the F connector in the bottem end cap. You could also add a hook in the top end cap to hang it from. If you don't glue them on, you can easily open the unit up for maintainance. This unit has no swr protection and requires the dipole antenna leads to be placed before applying power and drive. 
Completed Amplified Dipole Antenna, ready for the enclosure Tune up and use: This unit requires no tune up, as it is a broad band amplifier thats almost flat in performance accross the 88-108 Mhz frequency range. If your planning to use the Amplified Dipole Antenna outdoors you will need to seal the enclosure with silicon glue to keep out the harmful effects of the weather. Also you will need to seal the coax connector at the bottem with tape or heat shrink. The wire leads need to be cut for your desired frequency or left at 32" per side for the bottem (88-90 Mhz) of the band. You can use string or fishing line, tied to the ends to suspend the dipole, like for example, installed in the attic of your house! 
Amplified Dipole Antenna - ready to install 
Amplified Dipole Antenna - (Prototype circa 1998) - DJ Pirate Joe |
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