I need a rubber ducky antenna working at 44MHz, how should I start? Is there any book discussing the design of this type antenna? Any equations to calculate the parameters such as coil diameter, number of coil turns, etc? Thanks in advance.
1. What is the gain you want to design ?
for 44MHz it isnt going to have any gain !!
the antenna, event with some loading coils is still going to be substantially shorter than anything actyally resonant for that freq
Dave
Do a Google search for Normal mode helical antenna, this is what you are looking for.
Peter
Well that is how I have seen them described when they first started appearing on handheld radios and FWIW Wikipedia also refers to the term when used for this type of antenna.Is that true?
Deborah.
here is a helical antenna calculator
https://www.daycounter.com/Calculators/Helical-Antenna-Design-Calculator.phtml
A helical antenna operating in the normal mode is sometimes used as a monopole antenna for mobile cell and cordless telephones, and it is usually covered with a plastic cover. This helix monopole is used because its input impedance is larger than that of a regular monopole and more attractive for matching to typical transmission lines used as feed lines, such as a coaxial line.
A friend of mine used to work for a mobile radio company and I remember him tellling me about the antenna designer there would only measure these things on a large groundplane in the open with no one anywhere near. I expect he would be horrified if he realise how they were going to be used in real life; close to a lossy body, with the ground plane the skimpiest of metalwork surrounded by the lossy body's hand.
With such a variable evironment I'm supprised that they work as well as they do.
Peter
I Assume that the dimensions are inches, the ' abreviation means feet, " is used for inches.
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