Each Radiocommunications Service is allocated frequency bands appropriate to their use. The purpose of Maritime Services, for instance, is to provide efeective and reliable communications between boats and ships in coastal areas as well as between ships at sea and Sea Ports, Marine Rescue and Coast Guard services. There are two different needs, in terms of the range of communication distance, that must be met. Both HF and UHF Marine Bands exist specifically to accommodate these two needs.
HF is very good at propagating over large distances across water. UHF is very reliable over much shorter distances. The choice of these frequency bands was particularly sensible.
As Amateurs, we have a choice as to the Band on which we want to operate at any gien instance. That choice will depend on the prevailing conditions as well as what we wish to achieve.
Services such as Police and Ambulance are accommodated in a similar way. As Amateurs, we need to ensure that we do not transmit on frequencies that are allocated to other services, or interfere with the operation of those services.
Download a *.pdf copy of the Australian Radiofrequency Spectrum Allocations Chart and save it with your other reference documents. It will come in handy when we are discussing Amateur Bands and their relationships with other radiocommunication services. Note that on the chart, that has been produced by the Australian Communications and Media Authority (ACMA), the Amateur Bands are coloured a pale pink. You will also notice that each "one decade" section of the spectrum is on a separate row: VLF is 3 kHz to 30 kHz; LF is 30 kHz to 300 kHz; etc. The Radio Spectrum is broken into these broad bands because the behavior of radio waves changes as the frequency increases. It is similar to the way in which the Visible Light Spectrum is divided into bands of colour; going from RED (The lowest frequency) to VIOLET (The highest).
Zoom in of the Chart and find all the Amateur Bands in the HF section of the Spectrum. After doing this, try to find bands that are allocated to Services such as Maritime and Land Mobile.
How many Amateur Bands are there in the VHF band and what are their frequency limits? Next, have a look at the very wide Red Bands in the VHF region. What are they and why do you think they are so wide?
The 6m Band, from 50 MHz to 54 MHz, is only available to Standard and Advanced License holders. It is becoming very popular; especially as the 11 year solar cycle moves towards its peak. Click on the link below to watch a Youtube video about the 6m Band and how it behaves differently from HF or higher frequency bands.
In future topics, supplimentary videos, external web links and PDF files will be accessible here in the RESOURCES section. Only principal activity videos will be places in the ACTIVITIES section.
Always take the time to look at the supplimentary resources. Not everyone learns at the same pace and every individual has a different way of learning. Don't be frustrated if this website doesn't seem to meet your needs. The Internet is full of content in may different forms. Just use the Syllabus as a guide to find what you need.
This part of the topic will allow you to check your memory and understanding of the concepts that are covered in this one particular topic. It will contain a short series of questions that have been
written to align closely with the outcomes of the syllabus. Remember that the pass mark for the Amateur Radio Exams is 70% so try to reach the point where you can consistently get 4 out of 5 of these
self-check questions correct.
That would, if the self-check questions were in the exam, give you a confidence level of 80%