Presentations text content in Basic ½ Wave
Slide1
Basic ½ Wave Dipole Antenna
Presentation By:
Rodney Davis W3LDR and Chris Mabry KF5QIS
Lubbock Amateur Radio Club
Slide2The ½ WaveDipole Antenna
Benefits:Easy to build2.1 dBi Gain TypicalDirect Coax FeedPortable or Fixed Location UseGreat for State Side and DX Contacts
Slide3Dipole Fundamentals
A dipole is an Antenna composed of a single radiating element split into 2 sections. Not necessarily equal lengths. (However for Our Build it WILL Be)The RF power is feed into the splitRadiators DO NOT Have to be Straight
Slide4The ½ Wave Dipole
The length is approximately ½ waveSelf impedance is 40-70 ohms (Considered a good match to coax)Directivity 2.1 dBiSWR Bandwidth is approx 5% of tuned Frequency
Slide5½ Wave Dipole Typical OAL Length per Band
Slide6How to Calculate Length of Antenna
Simply Divide 468/Frequency = Total Wire Length
Total Wire Length / 2 = Each Dipole Leg Length
468 / 7.190mHz = 65.09ft 65.09 / 2= 32.55ft
Add 1ft Extra wire to Each Leg for Tuning
approx
331/2
ft
Slide7Wire Considerations
Solid vs. StrandedSolid Can and Usually will BREAK due to winds and movement. Subject to Corrosion.Stranded More Forgiving and Last MUCH LongerMost Popular wire size is 12-14 ga. Insulated Stranded
Slide8SuggestedBuild Materials
14ga Insulated Stranded Wire2 – Insulators (PVC, Plastic, Ceramic or Glass)Dacron or Quality UV Resistant Rope
Slide9Suggested Build Materials for Center
SO 239 Bulkhead Connector and Small Piece of Coax2” PVC 4-6” Long (Longer if Building Choke Balun)2” PVC Cap2” PVC Plug2” PVC Coupler¼” Stainless Eye Bolt x 3#8 Stainless Machine Screws x2 1 ½” Long, 2 - #8 Nuts, 4 - #8 Washers and 2 - #8 wing nuts (All Stainless)
Slide10Dipole Installation
A Dipole may be erected between 2 supports or with 1 supportA Dipole using one support is known as an Inverted-VThe legs of the Dipole may also be bent to form a Inverted U. The bend should be at least half way to the end of the wire.
Slide11NOW
WITH THE BUILD
Basic ½ Wave
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