The J-Pole antenna is herewith fixed
For what it’s worth, the myths surrounding the J antenna have been sorted out resulting in an improved version.
EFHW
The end-fed half-wave… discussing this is the equivalent of touching the third rail of antenna discussion in the various forums…. second only to “Pactor in ham radio.”
Adding 0.05 wavelength wire to EFHW antenna
I add a 0.05 wavelength wire to my previous end-fed vs. center-fed dipole tests and plot the results.
BOB, the battery operated “beacon” for APRS
I built a prototype APRS beacon, dubbed Thor Hammer (big), to test back-packable APRS 2m beacon concepts.
Electrically isolated end-fed vs. center-fed dipole radiation
Testing confirms an end-fed dipole can energize the radiator nearly as well as a center-fed without need of additional counterpoise or other extraneous conductors.
Not all mobile antennas are the same
Mobile antennas have been around for decades, but assuming they perform the same is, sadly, a poor assumption as this comparison of Laird and Larsen VHF NMO EFHW aerials reveals.
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.
EFHW transformer two ways
I take a moment to document observed differences between end-fed antenna transformer topologies with and without ferrite core materials with a focus on the reactance compensation.
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.
HT Antenna Comparisons
Does one really need to upgrade the antenna that came with your HT? Presented are EIRP measurements of various aftermarket HT aerials to help understand the trade space.
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.
Diamond NR770HBNMO vs. Comet M-24M
The Diamond Antenna NR770HBNMO paired with their K515S insulated luggage rack mount provides measurable and observable upgrade for my 2015 Subaru Forester 2m/440 mobile.
Displacement Currents
Displacement current explains why the ends of dipole antennas have something more than zero current.
Of fields and feedpoints
Understanding how feed position along the half-wave dipole antenna affects the electric and magnetic fields around it.
The dipole antenna, how industry defines it
Is a dipole antenna defined by its behavior alone or also how one energizes it? The answer exists in IEEE and historical literature.
EFHW LNR Precision EF-10/20/40MKII Test Data
Basic tests of the LNR Precision EF-10/20/40 multi-band portable HF EFHW antenna including S11, SWR and a bandwidth check of the match box.
EFHW LNR Precision EF-10/20/40MKII Examination
The background and details of the LNR (Par Electronics) EF-10/20/40 end fed half-wave multi-band portable HF antenna. Come see what’s inside the mysterious “black box.”