## 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.

## Validation of loop efficiency calculator

Efficiency and gain of Small Transmitting Loops (STL) referred to an online calculator (Calculate small transmitting loop gain from bandwidth measurement) for estimating the efficiency and gain of an STL.

This article documents an NEC-4 article of a 1m diameter tuned loop of 20mm diameter copper at 7MHz with a driving loop of approximately 0.2m diameter. Continue reading Validation of loop efficiency calculator

## The magic of small transmitting loops

Small Transmitting Loops (STL) are loops of less than about 0.1λ in diameter or about 0.3λ in circumference. Below these limits, the current around the loop is almost uniform and this permits a simplified analysis. (A stricter definition of 0.3λ in circumference could be argued.)

These antennas are ascribed all sorts of magic properties, low noise, able to create band openings when conditions are poor etc. Continue reading The magic of small transmitting loops

## Efficiency / gain of a Small Transmitting Loop – a worked example

This article uses a report of an experimental small transmitting loop (STL) for 20m to demonstrate application of the calculator Calculate small transmitting loop gain from bandwidth measurement to predict efficiency and gain of the circular STL from the loop radius, conductor radius and measured half power bandwidth. Continue reading Efficiency / gain of a Small Transmitting Loop – a worked example

## Efficiency and gain of Small Transmitting Loops (STL)

Small Transmitting Loops (STL) are loops of less than about 0.1λ in diameter or about 0.3λ in circumference. Below these limits, the current around the loop is almost uniform and this permits a simplified analysis.

STL are commonly known by Hams as “magnetic loops”, but that term is rarely used in recognised antenna text books.

The efficiency and free space gain of a circular STL can be easily estimated by calculation from simple measurements. Continue reading Efficiency and gain of Small Transmitting Loops (STL)