The Amazing Doublet Dipole G5RV

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This is post 2471 in a continuing series of simple ham radio antennas.

Another excellent choice for an HF multiband antenna is a G5RV and its variants.

In this video from "Ham Radio CQ", we get a good idea of the preparation and testing needed to make this "classic" HF antenna come to life.

Properly designed, this antenna will give you several Amateur Radio HF bands at a modest cost.

Here are some comments from the author: for more of MY VIDEOS!!! 🔥 As an Amazon Associate I earn from qualifying purchases. 👍 G5RV Antenna: 👍 Icom-7300: 👍 Jacktite Fiberglass Mast: 👍 TekPower: 13.8V Power 👍 Yaesu 891 👍 MFJ manual tuner My favorite ham gear: 👍 Sling Shot 4 tree antenna: 👍 Arborist Throw Box: 👍 Throw Bag2: 👍 Tree Antenna Weight: 👍 Youkits HB1B QRP Rig: 👍 Portable Speaker: 👍 CW Notes, Space Pen: Solder Station 👍 Work Bench found Here: 👍 Weller Solder Iron: 👍 Printed Circuit Board Holder #1: 👍 Printed Circuit Board Holder #2: My Favorite Camping Gear 👍 Foldup Camp Table: 👍 Mr. Buddy Propane Heater: 👍 Columbia Mens Mosquito Shirt: 👍 Hults Bruk Hatchet Axe: Dipole Doublet ~ Best Stealth Small Backyard Antenna for Ham Radio he doublet antenna is a form of dipole that uses a balanced feeder, often open wire feeder and an antenna tuning unit. As open wire feeder is able to operate with levels of standing waves and effectively becomes part of the antenna, it is able to operate over a wide band of frequencies. As a result, the doublet antenna forms a very convenient multiband antenna and it is often used at HF where a number of different HF bands need to be covered, and it is relatively popular with radio amateurs where it enables several bands to be used with a single antenna. Doublet antenna basics The doublet antenna is essentially a balanced system and each half of the top plus each wire in the feed line must be equal in length. The antenna top is not cut to resonate at any particular frequency (unlike the half-wave dipole), and any length may be chosen to suit an individual location. Basic doublet antenna concept Basic concept of a doublet antenna The key to the doublet antenna is the form of feeder used. Open wire or balanced feeders are able to operate as part of the actual antenna itself, not just feeding the power from an unbalanced source. The balanced feeder or open wire feeder is able to operate with standing waves along its length. Note on Balanced Feeder: Balanced feeder can come in one of a variety of forms: open wire, ladder line, or simple ‘ribbon feeder’. It provides the capability for very low loss, provided it does not pass near other objects that might cause imbalanced. Balanced feeder is often used on the HF bands. Read more about Balanced Feeder. Standing waves are a feature of radiating wires, but in the case of the open wire feeder, it consists of two equal length close spaced wires. As these carry equal and opposite currents their radiation cancels. However the feeder still remains part of the overall antenna itself. For a doublet, the top section is typically a minimum of λ / 4 for each section (length L1), i.e. a total length across the top of λ /2. However it is found that the top section, i.e. 2 x L1 can be reduced to about 3 λ / 8 without any major reduction in performance - it has about 98% of the efficiency of a half wave dipole, so the difference will not be noticed. The doublet antenna can operate over a wide range of frequencies and as a result the radiation pattern will change according to its electrical length with respect to the number of wavelengths, or part of that it represents. As the electrical length increases, i.e. as the frequency increases the antenna increases in the number of wavelengths it represents although the physical length remains the same. As the electrical length increases, so the phasing of the fields around the radiating element mean that the radiation changes from a figure of eight pattern for a half wave top radiating element to a pattern that has lobes that increasingly move towards the axis of the doublet antenna.


Thanks for joining us today.

Aloha es 73 de Russ (KH6JRM).


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