Additional loss due to VSWR – a quite flawed concept

The concept of “additional loss due to VSWR” is so engrained in Ham mythology.

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Here it is detailed in the latest version of TLW announced in QST June 2014. On the second last line TLW lists “additional loss due to SWR” as 0.003dB, which seems ok in relative terms as the cable is nominally matched (VSWR=1.03). Continue reading Additional loss due to VSWR – a quite flawed concept

A QRP small transmitting loop evaluation

The ‘net abounds with articles describing easy to build low cost small transmitting loops (STL).

This article describes measurement of a STL for 4MHz using RG213 coaxial cable for the main loop and its tuning capacitance, and a smaller plain wire loop for transformation to 50Ω. Continue reading A QRP small transmitting loop evaluation

ARRL Antenna Book 21 on small transmitting loops

The ARRL Antenna Book 21 (Straw 2007) gives equations and advice for design of small transmitting loops.

Many Hams have used these formulas and method for their designs, and some have even produced design tools (online calculators and spreadsheets) implementing these formulas.

This article reviews these formulas and advice. Continue reading ARRL Antenna Book 21 on small transmitting loops

OCF dipoles

Off centre fed (OCF) dipoles are very popular with Hams on HF.

Many claims are made for variations of the theme, but the essential common feature is that the offset feed point provides a feed point impedance that is not too unsuited to 50Ω coaxial feed line at the fundamental resonance of the dipole and half wave harmonics. Continue reading OCF dipoles