This article discusses the characteristics of a 102 ft. center-fed dipole antenna strung between two 37 ft. poles. It explores predicted feedpoint impedance variations across different frequencies and the corresponding impact on the VSWR for various feedlines, based on EZNEC antenna modeling software predictions. It also analyses how alterations in element lengths of antennas significantly affect their performance at higher frequencies.
C1 250pF or more C2 250pF or more L1 31 mH 39 turns, 2 Inches (51mm) Diameter, 4 Inches (102mm) long. Tapped at 20T, 14T, 9T, 5T L2 0.25 mH 4 turns 1.2 Inches (30.5mm) Diameter, 2 Inches long. I used silver plated copper wire for L1 and L2. If you use enamelled copper wire,
EH Antenna for 80 meters band,
an ultra compact antenna for 3.6 MHz
A moxon beam antenna for 10 meters band
By Kees Wiegers, PA5CW (ex-PA3BHS) It looked impossible to get a large beam for 20 meters up a tower, but it was something I always wanted. So after attending a presentation by John Devoldere, ON4UN, of Merelbeke, Belgium, I decided to try and build my own beam. At the presentation, John demonstrated software for designing
A four element Yagi Antenna for 50 MHz band. The reflector and the director elements can be mounted directly to the metallic boom, while the Driven element must be insulated from the boom. The driven element is basically a simple folded dipole and foreseen a 4:1 balun. Usage of a folded dipole as driven element
Article by M0DGQ This yagi antenna is particularly suitable for those with small plots ( myself included ) who wish to use a 2 element 20m yagi. The design is by AB4GX, the original article is listed below ( PDF ). Here different materials have been used for construction as these are easy to obtain
Quadruple Quad by Richard Price BSc. MSc. GW0VMW A suitable high gain 70cms antenna for SOTA operation was sought that did not have the drawbacks of a long Yagi antenna, principally a narrow beamwidth and bandwidth. This is important as operating from a hilltop on a relatively under used band requires as broad a catchment
Article by N5ESE Here’s yet another handy little Altoids QRP project. This makes a great travel companion to the 1:1 current balun and is intended to aid in tuning a balanced antenna or feedline that has a high impedance (100-600 ohms). I’ve even used it successfully to tune a 20 meter, 1/2-wave vertical with 4
Article by N5ESE Here’s another handy little Altoids QRP project. For Field Day 2002, I wanted to use my new Elecraft K1 (which has an automatic antenna tuner built-in) to feed a full-wave loop on 40 meters, to use on all bands 40 – 15. To preserve the feedline balance (I used 300-ohm ladder line),