moonraker 2500

Folding the Dipole - Invented by Heinrich Hertz in around 1886, the half wave dipole is still one of the most simple and practical of antennas and still very much in use today. It consists of a half wavelength long centre fed conductor

Feeder Radiation - Connecting centre fed antennas, dipoles, yagis, rhombics, loops to coaxial cable, unless care is taken, it is not difficult to end up with feeder radiation resulting in power loss and the radiation characteristics changes

The Coaxial Line - Impedance matching, Transmission Lines, Characteristic Impedance, VSWR & Mismatch and Antenna Losses

Antennas for MF and LF - Long Waves, Short Antennas, designing antennas for MF and LF communications

Quarter Wave Verticals - One of the most useful antennas in the repertoire is the Marconi or quarter wave grounded vertical antenna. Its invention made it possible to halve the length of antennas, simplifying communications, especially at HF and below.

Radiation Characteristics - Tailoring Patterns for HF Verticals

Polarization, lines of force - While polarisation may seem insignificant compared with other considerations in setting up a communications system, choosing the right type can make significant improvement in performance.

About broadband - What you gain and what you lose. While broadband and electrically small antennas may look attractive on the surface, they are by necessity compromises and usually don’t work as well as tuned antennas.

Azimuth Radiation Patterns - Below VHF the change in the radiation characteristics of an antenna will change considerably from frequency to frequency, making antenna selection more complicated.

HF insulation, the pitfalls - Although insulation may seem relatively insignificant in the larger picture, on it depends the quality of your performance on air and how long you will be communicating for.

Matching Waves, VSWR at work - When the radiation resistance (voltage to current ratio) of an antenna is the same value as the characteristic impedance of the transmission line (voltage to current ratio in the line), all of the electrical energy transmitted down the line is taken by the antenna and radiated into space in the form of a radio wave.

Earth Systems - In order to resonate at a particular frequency, an antenna needs to be at least one half wave length long. Antennas below a 1/2 wave are dependent on a ground system for resonance as well.

Antenna Gain on Trial - Most people think it's a good thing to have and the more the better. However, this is not always true - and the amount of gain is often not what it appears to be. Assuming higher gain is what you need, how do you determine what will give the best performance?

Moonraker  ^pop - Moonraker has been established since 1978. We are manufacturers of radio communication antennas and associated products.

Telewave - Telewave's innovative engineering produces the industry's toughest antenna systems. Yagi, Fiberglass Collinear, and Dipole models are available from 66-2500 MHz. Wattmeters, test equipment,rf power meters, duplexers, filters and cavities, transmitters combiners

Local Area Communications - Communications for short distances can be done in VHF or in HF mode, here is explained the differences.

VHF/UHF Propagation - In the past few years there has been a growing movement from VHF frequencies (50-300 MHz) to UHF (300-900 MHz). Many, however, have found the move fraught with difficulties.

The Ground Wave - About ground wave, article by moonraker.com.aut

BeamFinder - BeamFinder is a software tool designed to conduct analyses for radio amateurs interested in radio propagation studies. It provides a large 2500 x 1800 pixel screen map of the world which displays calculated results from sophisticated models, dx data and other sources of information

Spectra - Accurate spectrum analyzer in the range 0 - 2500 Hz, makes an accurate FFT analysis of an audio signal coming from the soundcard

iHamRelay - iHamRelay offers you more than 2500 repeaters all across Europe and the possibility for you to join the community while sharing your own data

Making the right connection - The humble connector plays a very important role in the communications chain. It can make or break your system - and often does.

When negative meets positive - Lightning can be a serious hazard depending where you live in the world. Chances are that if you living in an area where lightning strikes are common and you have a communications antenna, it may be attracted to you.

Lightning at Sea - Over 10% of deaths on cruising sailing boats alone at sea are caused by lightning.

Intermodulation - Intermodulation distortion, commonly known as Intermods, is a type of interference that can occur in any non-linear junction.