Mapping the Radiation Pattern of a Fixed Long Wire Antenna

The simple 20 meter pull-up vertical antenna I described last time has been working well.  I've been putting my efforts into working DX stations and have found that the vertical often does almost as well as the Off Center Fed Dipole (OCFD) despite its generally lower gain.  Part of the reason is that there are... Continue Reading →

Advertisements

A Simple Pull-up Mono-Band Verticle Dipole Antenna Design – and 4NEC2 Tutorial

I have a nice off-center-fed dipole (OCFD) antenna that is my mainstay for multi-band HF work, but I would like to understand it better.  With a wire antenna tied to trees it is not a simple matter to quantitatively determine the antenna's radiation pattern experimentally.  One way to get a handle on this is to compare... Continue Reading →

EPA’s Proposed Imidacloprid Exposure Limitations are Not Strong Enough

Our comment letter to EPA follows below.   OPP Docket Environmental Protection Agency Docket Center (EPA/DC), (28221T) 1200 Pennsylvania Ave. NW. Washington, DC 20460-0001   Re: Pollinator Ecological Risk Assessments: Imidacloprid Registration Review EPA-HQ-OPP-2008-0844   To whom it may concern, We would like to offer some comments on the regulatory endpoints that are proposed in... Continue Reading →

RTL-SDR Pan-adapter using HDSDR with the IC-751A

There is little doubt that the RTL-SDR tuner dongle radio receivers are the hottest new thing for the amateur radio experimenter.  Re-purposing the $10 tuner dongle to be an extraordinarily wide-band software defined radio is the subject of countless internet articles and videos.  Here I am adding my experiences to the crowd.  What I will describe... Continue Reading →

Antenna Comparisons using JT65 & JT9 Signals along with NEC Models

True understanding of a problem is confirmed when one can validate theoretical model predictions with measurements.  It is too easy to believe pretty pictures that modeling programs produce, especially when making meaningful measurements is so difficult.  In this article I try to take the bull by the horns and see how close I can come to... Continue Reading →

The Off-Center-Fed Dipole Antenna – Design

There are a few ways to build multi-band HF antennas.  These include multiple resonant dipole arrays, trapped dipoles, resonant loops and the off-center fed dipole, OCFD.  I'm going to look at the OCFD because it is relatively simple to construct, yet gets quite decent performance.  I also am fortunate to have some nice tall trees... Continue Reading →

Create a free website or blog at WordPress.com.

Up ↑

%d bloggers like this: