Dipoles fed with an open wire line are called “Double-Zepp” or “Doublet”. The dipole (2 x Xm) may have any length, the open wire feeder (2 x Ym ), too. You can choose the lengths as your local facilities allow.
At the feedpoint Z Z is a random impedance Z, which can be matched to 50 Ohm with an antenna tuner. We must differ three cases:
1. The impedance is very low. That is hard to match and the losses are high.
2. We have impedances from 15-100 +/- j X Ohm. In that case a Balun 1:1 is the right choice for open feeders.
3. We have medium impedances (200-600 +/- j X Ohm). That can be matched without any problems with the most tuners. If you have an asymmetric ATU use a balun 1:4 to match the open wire feeder.
4. The impedance is very high (> 1 KOhm). Most tuners have difficulties and the voltage in the matching system is extreme high.
1 and 4 should be avoided.
But how can we calculate the impedances at Z Z? The first method is “trial and error”. Connect the tuner and try to match the system. In many cases that will be successful, but it may be that some bands cannot be tuned. Then make the feeder shorter or longer and try it again.
ARRL is now accepting applications from individuals interested in becoming part of the new Volunteer Monitor program, a joint undertaking of ARRL and the FCC. The program seeks volunteers who — working under the direction of ARRL — will mon... Read more
More
![Ham Fair 2015 – Tokyo – Japan [ Video ]](https://qrznow.com/wp-content/uploads/2015/08/10984611_500529533435333_3509911180292586052_n-90x60.jpg)
By BOB BECKSTEAD MASSENA — Some J.W. Leary Junior High School students have discovered the joys of communication using technology that’s more t... Read more
The winning article for the November 2018 QST Cover Plaque award is “Build an Inexpensive Dummy Load with Wattmeter” by Jack Purdum, W8TEE, and Al Pet... Read more
As part of our quest to make it easier for new people to get into the hobby, Essex Ham has launched the Foundation Online Training Course. This new on... Read more
The 40/80/160 Meter Coil-loaded Inverted V Dipole Antenna See all details: Link Read more
This video shows how easy is is to set up an end-fed HF antenna and a fiberglass pole, even in non-ideal weather. Sorry for the water on the lens; the... Read more
Starting on August 1, the International Amateur Radio Union (IARU) will follow revised guidelines for satellite frequency coordination. Educational sa... Read more
International Space Station (ISS) Expedition 50 Commander Shane Kimbrough, KE5HOD, will take one more spacewalk on March 30 before he heads back to Ea... Read more
Organized ByBulgarian Federation of Radio Amateurs Date and periodThe weekend before the last full weekend of November (the weekend before CQWW CW con... Read more
The PowerGenius XL is a 100% duty cycle, legal limit (1500W ICAS) 1.8-54 MHz RF amplifier intended for both amateur and government use. It incorporat... Read more
Here are my thoughts and some preliminary test results with the Xiegu G106. It is a lack-luster radio, but I think they have fixed most of the bugs. Read more
The FCC Enforcement Bureau has called on on marketers of light-emitting diode (LED) signs to ensure that these lights comply with FCC rules. Since Mar... Read more
History of Morse Code Day April 27 is Morse Code Day, and it’s to honor its creator, Samuel Morse, who was born on April 27, 1791. The inventor played... Read more
The deadline to submit a design for the 2018 QST Antenna Design Competition is just ahead — September 1! The competition challenge is to design the be... Read more
It turns out that radio still gets results. Amid all the changes in television and digital media, a report from Nielsen released Tuesday found that ra... Read more
Testing the Wadetenna on 7 MHz SSB. Only 500 milliwatts was used instead of the usual 5 watts. Contacts up to about 500km, mostly to portable stations... Read more
More
Massena junior high school students honing skills in Morse code, ham radio operation
W8TEE and AC8GY Win the November QST Cover Plaque Award
Foundation Online – Amateur Radio Training
The 40/80/160 Meter Coil-loaded Inverted V Dipole Antenna
HF Portable Par End-Fedz EF-20, Jackite Fiberglass Pole Deployment
IARU Revises Satellite Coordination Guidelines to Align with WRC-15 Decisions
Ham-Astronauts Engaging in Series of Spacewalks; Two Heading Home Soon
LZ DX Contest
![PowerGenius XL – RF amplifier [ Brochure and Video ]](https://qrznow.com/wp-content/uploads/2017/02/amp-190x122.jpg)
PowerGenius XL – RF amplifier [ Brochure and Video ]
Xiegu G106 – My Thoughts and Test Results
FCC Tells LED Sign Marketers to Abide by Statutes and Rules
Morse Code Day
QST Antenna Design Competition Submission Deadline Looms
Radio audience hits all-time high
500 mW on 7 MHz with the Wadetenna
Warning: file_get_contents(https://plusone.google.com/_/+1/fastbutton?url=https%3A%2F%2Fqrznow.com%2Fthe-random-wire-double-zepp-antenna%2F): failed to open stream: HTTP request failed! HTTP/1.0 404 Not Found in /home/qrznow/public_html/wp-content/themes/goodnews5/framework/functions/posts_share.php on line 151
