Continuing my review of antenna basics, two nuggets of knowledge emerged after reading about attenuation and propagation velocity, written by Joel R. Hallas, W1ZR in Antenna Basics: Understanding Practical Antennas and Design (2012). The American Radio Relay League is responsible for publishing his work, and in my opinion, is a sincere credit to Hallas for extending wireless communication as an artform. Likewise, kudos to the League's publishing department for producing material of this caliber, it is an organizational strength.
My first knowledge nugget is attenuation and the use of open-wire line made of two parallel wires using air dielectric and spacers with a Zo of 600 Ohms according to Hallas (2012).
He suggested that losses within such a line are low including his nugget that is keep such line well spaced from metal objects and do not coil (2012). In contrast, the advantages of coaxial line include running inside conduit; can be coiled; and placed next to other wires. The current landscaping project in our regulated community may necessitate running my RG213 coaxial cable through PVC piping instead of laying on the ground. It's not conduit but it is good to know if one needs to route coax to a location inside the house.
Additionally, Hallas (2012) in the section propagation velocity on page 5-4, described why it is important to know velocity in relationship to timing and antenna pattern. He stated, "If a transmission line is used to provide two signals of different phase, we need to know how fast the signal propagates in order to determine the required line length."
His explanation resonanted with me and understanding why velocity factor is important when building phased verticals. It was, an imagine that, at least for my inner engineer.
Overall, learning about Zo that is do not coil open-line (600 Ohm) and keep it away from metal objects, was a knowledge nugget moment. Would Hallas' caution also apply to ladder line (450 Ohm) typically; I've never seen this type coiled although some suggested stand-off insulators during routing. Additionally, his propagation velocity explanation, answered my question about antenna pattern and phased verticals that is the importance of timing and line length.
Lastly, as we take this journey through the literature, let's keep in mind Micro dB Theory, and the impact of incremental changes effecting one's RadioSport score.
73 from shackadelic near the beach.