Magnetic loop antenna build

The magnetic loop design leads to antenna which is tuned to a very narrow frequency range, giving good selectivity. However, it also requires retuning quite often in order to stay on-band. Magnetic Loop Antennas for The Radio Operator with Limited Space pt.

In part one of this series, I covered the use of one brand of commercially available, small transmitting loop antennas , also known as ‘ magnetic loops ’. Ham radio folks: please comment!

Base is a (sadly now discontinued) speaker tripod stand. Reports on usage and tips to build the support. MHZ, description, construction details, homemade.

Well, its time to have a look at the first prototype. I’ve published the first build video and I thought it would be a great idea if I publish a page detailing all components, links, tools, and build ideas that have gone into making this video. I looked for alternative antenna designs online and discussed my challenging situation with other local hams, which led me to look into the magnetic loop antenna.

This type of antenna is a lot smaller than its more popular alternatives and is also a lot less efficient.

First, I tried something simple. Using the software at the bottom of this page, I worked out that a 36cm length of wire, will need a capacitance of around 3. Build a simple magnetic loop antenna. A key characteristic of magnetic loop antennas is the very narrow bandwidth when tune so that if you QSY a few kHz you need to retune the loop.

Loop antennas ( magnetic ) are known to accomplish this. So I build this simple active receive loop antenna to see if they work… and they do. The noise has reduced a lot and listening to the low bands is not annoying anymore. The simple active receive loop used was found on the internet (link = broken).

NEC simulation model adapted by me from Carol Milazzo, KP4M ref. A loop antenna is actually sensitive to the magnetic field and not the electric field (it is also called a magnetic loop ). Having built magnetic loop antennas thus far, using three different vacuum variable capacitors, generally I have found that when using this stepper motor, only about 250mA per phase is requ ired to reliably turn the capacitors (see antenna descriptions further down the page). What is a Tuned Loop Antenna ? Indeed there are two different types of loop antennas , The first of these is the ferrite bar as build into practically every portable radio, the other is wound on an air-core form, and is. Magnetic loop antenna enables the radio to pick up waves and convert them into sounds.

The best thing about these magnetic antennas is that they are very quiet, and electrical interference can’t affect them. There are several ways to build such an antenna , which have different names.

But they are all loop antennas. You need to remember to turn your antenna tuner off (or switch it to by-pass) each time you go to another frequency that puts your SWR above 2. This antenna works on 1 2 and meters, with the best bandwidth on meters. The bandwidth on and is quite small but usable.

This interesting feature makes the ground plane losses very low and generally this antenna has little dimensions. This article describes how to build a relatively small loop antenna which can be placed for instance at the balcony. My design is made for modest conditions, e. A MORE EFFICIENT MAGNETIC LOOP ANTENNA.

Variations on a Theme Continued. For the last five or so years, I have been using a rather different magnetic loop antenna. It was built with improved efficiency in min and it has served as a configurable testbed for experimentation. RG-Length not critical.

Loop and pre-matching circuit Uses a ladder line as impedance transformer The length of the ladder line is approx. Obtained from simulations.