Antennas – disturbing the thing being measured – open wire lines

A common question in online forums relates to inability to reconcile analyser measurements of an antenna system with the transmitter system antenna facing VSWR meter. The cause is often that the antenna system was changed significantly to connect the analyser. Seeing recent discussion by the online experts of how the measure the impedance of an … Continue reading Antennas – disturbing the thing being measured – open wire lines

Radcom Feb 2019 “cable balun” – a deeper look

This article is a continuing discussion of Radcom Feb 2019 “cable balun”. The article Baluns in antenna systems explores some different dipole and feed line configurations and the effectiveness of common mode chokes at various locations on the feed line. Models 1, 2 and 3 particularly show the effect of a quarter wave vertical common … Continue reading Radcom Feb 2019 “cable balun” – a deeper look

A low Insertion VSWR high Zcm Guanella 1:1 balun for HF

This article describes a Guanella 1:1 current balun which has high common mode impedance (Zcm) and low Insertion VSWR. It is for application on antennas that have low VSWR(50) on at least some bands, especially if they would be used without an ATU on some bands. The purpose of the balun is to minimise common … Continue reading A low Insertion VSWR high Zcm Guanella 1:1 balun for HF

Analysis of a certain dipole animation – OCF implications

A correspondent having read Analysis of a certain dipole animation questioned the validity of the lossy transmission line model of the dipole, citing the case of an OCF half wave which has an approximately resistive feed point. Since the OCF lacks the symmetry exploited in earlier study, we must consider each half of the OCF … Continue reading Analysis of a certain dipole animation – OCF implications