Graham began by stating that with small aerials you can’t have all the most desired features regardless of what the advertisements say. He defined what a ‘small antenna’ would be with regards to your available garden. i.e. any antenna too small to be resonant at the desired frequency, a dipole less than a half wavelength, a loop less than one wavelength in circumference, a vertical less than a quarter wavelength in height. However, a small aerial can be effective with careful design.\u00a0 Graham spelled out what we should design for, such as being able to radiate as much RF as possible and to hear weak stations especially on Top Band.<\/p>\n
A number of different matching networks were considered and Graham showed the pitfalls of some and the advantages of others.\u00a0 At this point, he introduced the software programme Sim Smith<\/em> which can introduce various circuit arrangement for best matching and display the results. Some looked like the most used methods of matching but the programme showed heavy losses in their use. The programme showed the advantage and disadvantage of some baluns and ATUs and where they were best placed.<\/p>\n More discussions followed the use of Sim Smith and how the active Smith Chart could actually make design much easier and faster. \u00a0At this point, we ran out of time but Graham said he was willing to come again next week to explain more about the matching conundrum.<\/p>\n","protected":false},"excerpt":{"rendered":" Graham began by stating that with small aerials you can’t have all the most desired features regardless of what the advertisements say. He defined what a ‘small antenna’ would be with regards to your available garden. i.e. any antenna too small to be resonant at the desired frequency, a dipole less than a half wavelength, … Continue reading 10 Mar 2022 – Optimising Small antenna systems by Graham, G4JBD<\/span>