Number of turns for the coupling loop - Page 1
Forum section: electronics / rf-microwave

author: prabhatkarpe4
author_rank: Contributor
timestamp: September 27, 2024, 02:22:54 pm
content: I need to know one thing about using a coupling loop with a small loop antenna.If I use N number of turns for the main loop then how many turns of the coupling loop should I use to connect the radio?If I use 1:1 ratio for the main loop : coupling loop then is it going to be correct and effective? Or should the main loop be greater than the coupling loop?I have attached a diagram for clarification.

author: A.Z.
author_rank: Super Contributor
timestamp: September 27, 2024, 02:27:54 pm
content: You are joking, aren't you ?Because, if not, then my humble suggestion is to find some good books about antenna theory (there are a lot of free ones) and start by understanding how things work.Also sincehttps://www.eevblog.com/forum/profile/?area=showposts;u=1017709

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 27, 2024, 09:12:17 pm
content: Well, there are two answers.One, you need to fully specify your system: frequency, bandwidth, tunable range, gain, receiver impedance, maybe efficiency as well, or other circumstantial parameters like maximum size, or material cost. Then, those who understand the below, can do the design for you. You get one (1) design for little effort, butyou have to specify the system fully.Two, you learn AC steady-state circuit analysis and network theory. This is a deep subject, working in the mathematical domains of complex numbers and rational polynomials. It takes years of concerted study to become fluent at it; but despite the multiple levels of abstraction, it's perhaps surprisingly easy to work in the outer levels, for example plotting the frequency response of a network, and simulating in SPICE or whatever. It's a lot of playing around to begin to recognize and grasp the symmetries of this topic, but it is possible to see it just by tweaking component values a few at a time. Some simple equations also run deep: Fo = 1 / (2 pi sqrt(LC)) and Zo = sqrt(L/C) will never not be useful in this study. After all this effort, you will be able to design pretty much any network for any purpose you could want -- whether coupling an antenna, filtering an amplifier's passband, or more. Even more, you can specialize into RF engineering, and perhaps start a lucrative career around it -- skills that go this deep are hard to come by. Rather than getting one design, you get access to... all of them, essentially; your imagination's the limit. But it takes a lot of work to get there.And it's not an all-or-nothing thing. You can poke around blindly in SPICE and on the breadboard, and find something "good enough", or that takes a few more components than is optimal, or has crappy (but again, still good enough) pass/stopband ripple or skirts or whatever -- but you won't really know why it works, or how to "do it right", until you've spent a long time with problems like these.Tim

author: radiolistener
author_rank: Super Contributor
timestamp: September 27, 2024, 09:21:20 pm
content: google for gamma match, but in order to properly tune it you need to use antenna analyzer

author: prabhatkarpe4
author_rank: Contributor
timestamp: September 28, 2024, 11:07:34 am
content: Instead of suggesting me to upgrade my RF knowledge, I would appreciate if you could give a solution on building a small loop antenna.

author: tggzzz
author_rank: Super Contributor
timestamp: September 28, 2024, 11:16:26 am
content: Quote from: prabhatkarpe4 on September 28, 2024, 11:07:34 amI think people are indicating how you might "upgrade" yourunderstanding. That is very different from "knowledge", and much more useful.There is an English proverb: "Give a man a fish and you feed him for a day. Teach a man to fish and you feed him for a lifetime"

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 28, 2024, 12:30:01 pm
content: Ok, then that will be the "single design" route.What are your variables, then?Tim