Antenna Design Calculator
Calculators for various antenna designs.
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PD9JS - RF Antenna calculators for various antenna types

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Radio waves behave very similar to the photons in light waves. The wavelength calculators used to calculate the antenna element dimensions will therefore use the speed of light (299792458 meters per second) in a vacuum as constant. Note: when using coax for antenna elements it is advised you lookup and apply the velocity factor because RF slows down in coax and this will impact the effective measurements for antenna elements.

J-Pole Antenna Calculator

J Pole Antenna Design

An omni-directional end-fed half-wave antenna with a quarter-wave transmission line matching stub. Invented by the Germans for use on their zeppelins, this antenna is also referred to as a Zepp antenna. In 1936 this design was modified into the current configuration used today and became popular with amateur radio operators by 1943.

Slim Jim Antenna Calculator

Slim Jim Antenna Design

A variation of the J-Pole antenna invented by Fred Judd (UK). An omni-directional folded dipole with a quarter-wave j type matching stud. It gets its name from its Slim constructions and J Integrated Matching.

Quarter Wave Antenna Calculator

1/4 Wave Antenna Design

This is a design is called a monopole antenna. Invented in 1895 by Guglielmo Marconi (IT) who discovered that if he attached the live terminal of his transmitter to a wire perpendicular to the earth and the other terminal was attached to earth, he could transmit for long distances.

It is made of a straight rod conductive material mounted perpendicular to other conductive material or surface that is referred to a the ground plane.

As the dipole antennas, the monopole antennas are also omni-directional, this means they transmit and receive equally well in a 360 degree plane around their axis.

The antenna calculator assumes the antenna will be mounted on a mast, and not be close to actual ground. Hence the addition of ground plane elements.

Coax Collinear Antenna Calculator

Coaxial Collinear Antenna Design

The coaxial collinear antenna is made from two or more sections of coax cut to length for a specific frequency and connected to each outer in an 'out of phase' manner ending with a quarter-wave matching stub. The elements can be quarter-wave or half-wave. I have found that half-wave elements, not more than eight, give the best result. Strangely enough this operates without a ground-plane.

Collinear Dipole Antenna Calculator

Collinear Dipole Antenna Design

The collinear dipole, unlike the coaxial dipole requires a ground-plane to operate. A dual element collinear dipole gave me the same results as an eight element coax collinear. Although this design is not ideal for a 'pipe antenna' it is ideal for mounting in any antenna mast.

Udo Yagi directional antenna calculator

Antenna DMR Hotspot Booster

One of the more complex antenna calculators, this one is directional and was built for the purpose of making a directional antenna for the purpose of tracking the smart falconry telemetry transmitters.

A load of research went into this one as there are several ways to construct this type of antenna, from fixed interval directors to calculated delay time director spacing. This uses the latter.

UHF DMR hotspot booster antenna

Full Wave Loop Antenna

This design uses the 'good old' HF full wave antenna design principle. It scales down to a small very portable antenna about four times the size of my OpenSpot transceiver. It has boosted my range from 158 meters to 600+ meters. An added benefit is that is 50 Ohm by nature, so coax can be connected to it directly.

Short whip antenna

Short whip Antenna

In situations where it is not possible to implement a resonant antenna element, due to lack of space or environmental limitations, a loaded short whip antenna is an alternative. This calculator calculates the value of the loading coil required to compensate for the capacitive effect of antenna elements that are to short for the frequency they are required to operate at.

This calculator was specifically designed for the light weight low power falconry telemetry transceivers that can be attached to birds of prey and other small (wild) life. Here the size of the antenna is limited in such a way that it may not cause hinderance, discomfort or interfere with the natural movements of the subject it is attached to.

UHF VHF wire antenna tips

My experience has shown that copper is about the best material for conducting electro magnetic waves. When building VHF and UHF antennas, normal building insulated copper wire, available at any hardware store is the perfect candidate. The problem is that it is usually rolled up and difficult to get straight. The tip here is to cut a length a bit longer than you require for the antenna from the role. Attach one end to a fixed point, a table leg or door handle will do. Attach the other end to a drill, pull the cable slightly taut and give the wire a good few spins. The result will be a perfectly straight piece of copper wire. The added benifit of doing this is that it also hardens the copper wire, making it stiff and less easy to bend. Perfect for making wire antennas.