The Flexible Arnold is a simple antenna for VHF
This antenna is particularly suitable for WICEN/DARES activities
(after an article by DARES, this after an article by PC1D, translated for WICEN by VK2MOH, redacted by VK2FEB, proof readied by VK2VAN, technical scrutiny by VK2YVA)
The antenna has several remarkable features: It is cheap, easy to build, hardy and above all easy to carry, making it a great WICEN antenna.
In fact, this antenna is an end fed half wave dipole. It is made by stripping about half a wavelength of coax from half of the outer jacket and winding the coax on a piece of PVC pipe into a coil at the other end.
Use is made of the property that the shield of a coaxial cable can carry different high-frequency currents on the inside and outside. Due to this property, the feed point is positioned at the halfway point of the antenna construction. (A/B junction) The currents flow from there through the stripped core to one end, and along the outside of the mantle to the other end. At that point, the coil (choke) ensures that the HF on the outside cannot continue.
We have adapted the design for 4 bands. The ARRL handbook from 2002 presents a similar design for the HF bands. The antenna can be used both horizontally and vertically and upside down. Hanging from a squid pole should give a good setup. Conductors in the immediate vicinity can influence the SWR.
The material needed is a piece of PVC pipe, 75mm, 45mm or 90mm length, 2cm of heat shrink, RG58 coax, cable ties and a plug. For 2 meters and VHF we use 25mm pipe and for the 6 meters, a pipe with a diameter of 50mm.
|BAND||Freq (MHz)||A (in mm)||B (in mm)||C (in mm)||WINDINGS|