Basic ½ Wave

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Basic ½ Wave

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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 build2.1 dBi Gain TypicalDirect Coax FeedPortable or Fixed Location UseGreat 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 splitRadiators DO NOT Have to be Straight


The 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


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





Wire 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


SuggestedBuild Materials

14ga Insulated Stranded Wire2 – Insulators (PVC, Plastic, Ceramic or Glass)Dacron or Quality UV Resistant Rope


Suggested 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)


Dipole 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.




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