Of end-feds and feed-lines
Simulations suggest end-fed and center-fed half-wave dipoles share sensitivity to various feedline lengths, but in differing and manageable ways.
Simulation
Antenna simulation using NEC (EZNEC, 4nec2) and FDTD.
Simulating the end-fed half-wave (EFHW) dipole antenna
A NEC model that includes the transformer helix helps demystify the end-fed half-wave (EFHW) dipole antenna using the autotransformer as impedance converter.
Antenna radiator decoupling stub flub?
Measurements and analysis suggest why quarter-wave stubs fail to completely isolate radiator conductors on multi-band antennas including the popular rollup 2m/440 J-Pole products. Possible improvements are shown.
Where quarter-wave radiator decoupling stubs work… and don’t work
Tests suggest transmission line decoupling stubs are not immune to the conductor past the stub.
EFHW HT antenna functions without additional counterpoise
EIRP measurements of the 2m end-fed half-wave HT antenna from MFJ aids understanding a dipole is a dipole no matter where you feed it.
Of fields and feedpoints
Understanding how feed position along the half-wave dipole antenna affects the electric and magnetic fields around it.
SlimJIM and Antenna Gainflation
Understanding why SlimJIM antenna aficionados hype the gain in their marketing and discussions.
Slim Jim vs. Traditional J-pole Antenna
Real measurements of a Slim Jim antenna and traditional j-pole antenna reveal the truth about their respective gain and pattern.
NVIS Gain of Loop and Dipole vs. Height
Observations from the Virginia QSO Party confirm simulation results concerning horizontal antennas and NVIS propagation.
Mast Mountable J-Pole Antenna
The J-Pole antenna’s long and storied design history is due for one more chapter to mitigate the longstanding mast current and reliability issues.
Have your J-Pole and ground it too
Tame the predictable mast currents found in any j-pole antenna grounding conductive mast using a simple stub. Shown is empirical evidence why this is a problem and a very simple solution all future grounded j-pole antennas should incorporate.
The Coaxial Dipole
G4CQM provides details on a Yagi-Uda coaxial dipole driver approach for designers lusting after a 50 ohm self-balancing feed.
HF AHVD on 6m – Practical?
Will the KX4O version of the 20-10m Asymmetrical Hatted Vertical Dipole work on 6m? Yes, sort of.
Build this Vertical Portable HF Antenna
The Asymmetrical Hatted Vertical Dipole (AHVD) prototype is an easy to build, portable alternative to other freestanding vertical HF antennas such as the Buddipole.
Asy Hat Vertical Dipole
We re-introduce the theory and origins of Cebik’s (W4RNL) Asymmetrical Hatted Vertical Dipole (AHVD) antenna with the hope to facilitate a vertical polarization portable 20-10m aerial for portable operations.
40m Mastless NVIS Antenna
Yet another 40m Cloud Burner design featuring a folded dipole driven element plus one reflector wire to facilitate 40m NVIS contacts without need of a tall mast. The design uses electric fence posts for support and needs no balun.
Of Horses and Hams
One example of how amateur radio provides safety and service to the pubic providing otherwise impossible communications using the “Magic Band.”
Wideband 80m Dipole
A 1/4 wavelength of 75 ohm coax inline with a full wavelength of 50 ohm coax is all one needs to make a simple 80m dipole become a wideband dipole antenna.
Superbowl HDTV Antenna
Build the venerable Hoverman TV antenna and watch digital broadcast high definition HDTV television this weekend. This version of a HDTV antenna uses amateur radio antenna building techniques to make a lightweight structure.
Copper 6m Coplanar LFA Yagi-Uda
The Coplanar Loop Fed Array (LFA) Yagi-Uda design from G0KSC provides an excellent design foundation for an all copper version of a 3 element 6m balunless beam with superior front to back performance. Shown are comparisons between model simulations and prototype measurements.
Coplanar Loop Fed Array LFA Yagi-Uda Antenna
The clever application of the folded dipole loop, computer science iteration techniques and NEC simulation to Yagi-Uda design results in a panoply of practical planar Loop Fed Array, LFA Yagi antenna recipes.
Improving the Super-J
The traditional collinear J-Pole, aka Super-J, improves the basic J-Pole. Are further improvements possible? By replacing the phasing stub with a simple coil, the answer is yes. The result is the Collinear J-Pole.