Original article from: Wayne Sarosi 
 Reposted by Rob Dennis,Moderator HAM_TECH,for use of the FIDO HAM_TECH echo.
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SUBJECT: Part 2,Bird Feeder Antenna
 Now,I admit,this design sounds a bit far fetched,but it works. The vertical
dipole,inside the PVC push-up,is invisable. It moves up and down and can be
removed without drawing attention to the fact that it contains an antenna.
 The flagpole design has some problems.
 Not all PUDs,condos,or apartments allow flagpoles. They represent a 
ermanent
fixture. Not all associations or managers are that patriotic.
 Although you can pack a good vertical in a flagpole,there is the problem of
radials.
 You can run the vertical without radials,but that's another compromise.
 The design for the Bird Feeder Antenna is very simple. Drawing it here is
another problem. Ascii Graphics really do not exist,so a description is in
order. You can build the vertical dipole without much trouble.
 The dipole consists of up to 16 wire 1/4 wave elements.
 There are eight on each leg of the dipole.
 You may use less,it's up to you. You know the bandwidth of a wire dipole and
you know the band spread on 10m. If you are a general or above,you will want
the extra wire elements to give you the bandwidth you need.
 First,let's look at the PVC tubular mast / bird feeder support.
 Most hardware and home improvement center have PVC tubing.
 Like the steel counterparts,the mast will be graduated (large at the bottom
and smaller at the top. I'm not going to recommend sizes here as availability
at your store is going to dictate what sizes you will need. I will state the
the top tube should be 2" in diameter or better. You will need that size to
support the bird feeder and give the mast some strength.
                                ___
                                | | <-------  Attach upper ring
                                | |           inside
                                | |
                                | |
                                |_| <-------  Attach next ring
                               |   |          inside
                               |   |
                               |   |
                               |   |
                               |___| <------- Attach feed ring inside
                              |     |<------- Attach feed ring inside
                              |     |
                              |     |
                              |     |
                              |_____| <------ Attach feed ring
                             |       |        inside
                             |       |
                             |       |
                             |       |
                             |       |
                             |_______| <------ Attach bottom ring inside
                   Figure 1.
 The wire elements are attached in a ring format,evenly spaced,in a 360 
egree
pattern. Locations are noted in figure 1. This allows the dipole to be folded
up when the mast is lowered. More than eight wires on each leg of the dipole
tends toward snags when raising and lowering.
 Dipole wire element sizes are calculated by 246 / f Mhz.
 But I recommend shorter lengths if eight elements are used.
 A BALUN can be inserted,but is not necessary. I feeder coax is needed from
the dipole feed to the base of the mast. A UHF bullet (female to female) to
attach your coax to.
 NEXT: How to lay the coax without looking like you're doing it and Bird
Feeder mast install.
NEXT ANTENNA: Mobile resonators and hiding them.
-WS
--- GoldED 2.42.G1219
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