Basic ½ Wave Dipole Antenna Presentation By: Rodney Davis W3LDR and Chris Mabry KF5QIS Lubbock...
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Transcript of Basic ½ Wave Dipole Antenna Presentation By: Rodney Davis W3LDR and Chris Mabry KF5QIS Lubbock...
Basic ½ Wave Dipole Antenna
Presentation By: Rodney Davis W3LDR and Chris Mabry KF5QIS
Lubbock Amateur Radio Club
The ½ WaveDipole Antenna
Benefits:
Easy to build
2.1 dBi Gain Typical
Direct Coax Feed
Portable or Fixed Location Use
Great for State Side and DX Contacts
Dipole 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 split
Radiators DO NOT Have to be Straight
The ½ Wave Dipole
The length is approximately ½ wave
Self impedance is 40-70 ohms (Considered a good match to coax)
Directivity 2.1 dBi
SWR Bandwidth is approx 5% of tuned Frequency
½ Wave Dipole Typical OAL
Length per Band
How 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
Wire Considerations
Solid vs. Stranded
Solid Can and Usually will BREAK due to winds and movement. Subject to Corrosion.
Stranded More Forgiving and Last MUCH Longer
Most Popular wire size is 12-14 ga. Insulated Stranded
SuggestedBuild Materials
14ga Insulated Stranded Wire
2 – Insulators (PVC, Plastic, Ceramic or Glass)
Dacron or Quality UV Resistant Rope
Suggested Build Materials for
CenterSO 239 Bulkhead Connector and Small Piece of Coax
2” PVC 4-6” Long (Longer if Building Choke Balun)
2” PVC Cap
2” PVC Plug
2” PVC Coupler
¼” 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)
Dipole InstallationA Dipole may be erected between 2 supports or with 1 support
A Dipole using one support is known as an Inverted-V
The 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.
NOW
WITH THE BUILD