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I needed an antenna to chase down a noise source.. After much ado I settled on some plans I found on the web, added my own modifications & took some photos along the way. It has a cardoidal pattern with a deep null on the rear. I made a few minor changes to the original design but these were mostly for structural integrity, looks & ease of assembly.
This antenna will DF noise or signals in the area of the 2 meter amateur radio band..(144 - 148 MHz). I have tried it as high as 155MHz with good results. It is flexible so it won't break or bend as will most commercial directional antennas. It also tunes well on the 2 meter band.
You will need the following:
# A tape measure with a 1 inch wide steel tape. (Or a replacement tape)
# 3 PVC crosses for 1/2 inch pipe.
# ~3 ft section of 1/2 inch PVC pipe.
# 2 stainless hose clamps for 1 1/4 dia hose.
# Electrical tape.
# Soldering iron & associated tools.
# 6 feet or more of 50 Ohm coax & connector (BNC, PL-259, SMA...)
# Scissors or small shears to cut steel tape.
# Hack saw or tubing cutter to cut pipe.
# A Dremel tool is handy but sandpaper will do.
# You will need a receiver that has an "S-meter" to locate the direction of the signal.
This antenna will DF noise or signals in the area of the 2 meter amateur radio band..(144 - 148 MHz). I have tried it as high as 155MHz with good results. It is flexible so it won't break or bend as will most commercial directional antennas. It also tunes well on the 2 meter band.
You will need the following:
# A tape measure with a 1 inch wide steel tape. (Or a replacement tape)
# 3 PVC crosses for 1/2 inch pipe.
# ~3 ft section of 1/2 inch PVC pipe.
# 2 stainless hose clamps for 1 1/4 dia hose.
# Electrical tape.
# Soldering iron & associated tools.
# 6 feet or more of 50 Ohm coax & connector (BNC, PL-259, SMA...)
# Scissors or small shears to cut steel tape.
# Hack saw or tubing cutter to cut pipe.
# A Dremel tool is handy but sandpaper will do.
# You will need a receiver that has an "S-meter" to locate the direction of the signal.
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Signing UpStep 1Cutting the tape measure
Remove the tape from the tape measure and use the tail end for your elements.. This part sees much less wear & tear than the first 10 ft or so.
Measure your elements to the following dimensions.
# Reflector: 41 3/8 inches
# Driven element: 35 1/2 total.. cut in half for 2 @ 17 3/4 inches
# Director: 35 1/8 inches
These can be cut with regular scissors.. BE CAREFUL.. The ends will be quite sharp. I cut all ends with 45 degree angles. Some folks have taped or dipped the ends in Plasti-Dip but I just sanded mine a bit to take the sharp corners off.
Measure your elements to the following dimensions.
# Reflector: 41 3/8 inches
# Driven element: 35 1/2 total.. cut in half for 2 @ 17 3/4 inches
# Director: 35 1/8 inches
These can be cut with regular scissors.. BE CAREFUL.. The ends will be quite sharp. I cut all ends with 45 degree angles. Some folks have taped or dipped the ends in Plasti-Dip but I just sanded mine a bit to take the sharp corners off.
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Adam
KJ4ZVQ
If there's a ham in your are with an antenna analyzer then some experimentation will set you on course.. The short answer is... as the frequency decreases, the element length increases. Make one with ALL elements a couple inches longer then trim to the resonant frequency.
73 & good luck.
Fn
For 2 meter work I'd recommend staying with the 50 ohm coax. Most 2 meter gear is made to a 50 ohm standard.
Strength and rigidity are NOT the strong points... Flexibility & ease of use apply far better.
That "flexibility" was one of the things I liked about the idea. If you're fox hunting and need to run thru the brush then hold it in front of you with the convex side forward & it folds around you. Try that with an Arrow Antenna!!!. Similar specs with a 50 dollar price tag!!! One day of fox hunting & you have some scrap aluminum.
73..& sorry bout delay in response..
FN
73's, KC2VDM
Good Luck & 73
N1MLF ..fn64.. Jon