144MHz Band: 144.0 – 146.0MHz
144MHz Band Licence Conditions
In the UK the 144MHz band between 144.0-146.0MHz is allocated to the Amateur Service and Amateur Satellite Service with Primary status.
The power limit for Full Licensees is 400W (26dBW), Intermediate Licensees power limit = 50W (17dBW) and Foundation Licensees power limit = 10W (10dBW).
Schedule-2 of the Ofcom licence conditions includes a restriction on unattended use near Scarborough.
UK 144MHz Band Plan
The philosophy behind band planning is that it assigns frequencies for certain activities in such a way that all current users can practice the various modes of amateur radio with a minimum of mutual interference. The 144MHz UK band plan is based on the International Amateur Radio Union (IARU) Region-1 band plan.
The plan shows the frequency limits of individual ‘sub-bands’ or segments. The allocation of sub-bands enables the indicated category of users to employ any frequency within that sub-band provided that no appreciable energy falls outside that sub-band. Users must therefore take into account the bandwidth of their sidebands when selecting an operating frequency.
The ‘Usage’ column indicates the main usage of a sub-band or segment. It contains meeting/calling frequencies agreed upon for the convenience of the VHF. operators practising specific modes of communication. These frequencies are not part of the adopted 144MHz IARU Region 1 Band Plan and although in the normal amateur spirit other operators should take notice of these agreements, no right on reserved frequencies can be derived from a mention in the usage column.
The ‘transmission bandwidth’ determines the maximum spectral width ( -6dB points) of all emissions recommended in a sub-band. The mode indicates the modulation methods (e.g. telegraphy, telephony, machine generated mode) allowed in a segment. A machine generated mode (MGM) indicates those transmissions relying fully on computer processing, for example FSK441, JT65B or PSK31.
144.000 – 144.025MHz All modes (CW/SSB/MGM)
This 25kHz wide sub-band has been made all-modes so it can be shared with the downlinks from new amateur satellite linear transponders. The maximum transmission bandwidth is of 2.7 kHz. Users of the satellites need to account for Doppler shift to ensue they stay inside the bottom band edge.
144.025 – 144.150MHz Telegraphy (CW)
This 125kHz wide sub-band is allocated to modes with a maximum transmission bandwidth of 500Hz.
The bottom 85 kHz is allocated exclusively to CW operation. Operators using Morse should call CQ on 144.050MHz and then move to a clear frequency if answered. The top 40 kHz of this CW. sub-band is shared with PSK31 (144.138MHz) and Earth-Moon-Earth (EME) activity that is using the JT65B digi-mode.
144.150 – 144.399MHz Narrowband modes (CW/SSB/MGM)
Narrow-band modes with a maximum bandwidth of 2.7 kHz are always found at the low frequency end of any VHF or UHF allocation. This is where you will find Morse (CW), telephony (SSB) and machine generated mode (MGM) activity such as JT65 and FSK441.
In addition to the separate CW sub-band this is the area of the 144MHz band where all the DXers (and casual) operators make long-distance contacts. Stations using SSB call CQ on 144.300MHz and then move to an alternative frequency once contact is established. So always find a clear frequency that you will move to before calling CQ.
The narrow-band modes segment is actually divided into three sub-bands with MGM being allocated in the bottom and top slots. The bottom 30 kHz slot is to accommodate JT65 being used for EME communication in addition to conventional CW and SSB activity. The top 40 kHz slot is also shared with CW and SSB. activity but here you will find FSK441 being used around 144.370MHz for meteor scatter operation.
144.400-144.500MHz Propagation Beacons Exclusive
This area of the band is specifically allocated for propagation beacons only. Please do not transmit in this segment especially if you are using FM equipment. Such transmissions cause severe interference to weak-signal users listening for far away beacons. Strictly speaking the beacon band encompasses 144.400-144.490MHz with a 10 kHz guard band up to 144.500MHz. However an allocation has been made on 144.4920MHz +/- 500Hz for Weak Signal Propagation Reporter (WSPR) beacon transmissions. A small number of beacons located on the Atlantic coast have been allocated frequencies within the beacon band. They are beaming towards North America as part of a transatlantic propagation experiment.
144.500-144.794MHz All Modes*
This area of the 144MHz band is allocated to any mode with a maximum bandwidth of 20kHz. Here you can find a mixture of telephony and other modes that can include data, digital voice calling and image modes (Slow-scan TV, Fax etc). The use of amplitude modulation (AM) is also acceptable within the All Modes segment but users are asked to consider adjacent channel activity when selecting operating frequencies. A number of AM users are now using 144.550MHz for their telephony contacts.
144.794-144.990MHz Machine Generated Modes (MGM)
Machine generated modes with a maximum allocated bandwidth of 12 kHz will be found within this sub-band. The modes, some of which can be unattended, include Automatic Packet Reporting System (APRS), Digital Voice Gateways and AX25 (packet) data systems.
144.9900-145.1935MHz Repeater Input Channels (FM/DV)
There are 16 common repeater channels allocated throughout IARU Region-1 all using a 12.5kHz channel spacing system. The input channels commence at RV48 (145.0000MHz) continuing through to RV63 (145.1875MHz).
145.2000-145.5935MHz Simplex Channels (FM/DV)
Nestled between the repeater input and output frequencies are around thirty simplex channels. These all adopt a 12.5kHz spacing regime and are designated V16 (145.200MHz) through to V48 (145.5935MHz). Here you will find both fixed station and mobile activity especially around the mobile calling channel on 145.500MHz.
145.5935-145.7935MHz Repeater Output Channels (FM/DV)
The 16 repeater output frequencies are located 600 kHz higher than the input frequencies and this is commonly known as the repeater ‘shift’. The output channels commence at RV48 (145.6000MHz) continuing through to RV63 (145.7875MHz). Until recently all voice repeaters used frequency modulation (FM) but this is slowly being superseded by digital voice (DV) communication. Therefore you are likely to find a mixture of FM and DV throughout the repeater network.
145.806-146.000MHz Amateur Satellite Service – All Modes
Right at the top end of the band is an area exclusively allocated to the Amateur Satellite Service.
Take a listen in this segment and you might hear CW, FM, SSB or MGM signals from a series of low-earth orbiting amateur satellites. Mention should also be made of the channel pairing on 145.200MHz (uplink) and 145.800MHz (downlink) that are recommended for split-channel operation with manned spacecraft such as the International Space Station (ISS).
Getting Started on 144MHz
One of the great attractions of 144MHz operation is that with 2MHz of bandwidth to play with there are so many different ways of using this amateur service allocation. Do you only want to chat with stations in your immediate locality or do you want to make DX contacts with stations much further afield. Do you want to operate from home, in the car or go out hill-topping? What communication methods are you interested in using? Will it be via Morse code, telephony or data? Are you going to use FM or SSB or a computer generated mode? How about internet gateways, repeaters or satellites?
How many times have you heard a station saying that they can’t hear any activity on the 144MHz band? Probably quite often but when you ask that station what antenna they are using the answer is possibly a small vertical, maybe a Slim-Jim, fed with 20m of rather thin coaxial cable. They might as well be using a piece of wet string! The fact of the matter is that to make the most of operating on the 144MHz you need a good antenna and a short length of high quality low-loss cable.
As you no doubt appreciate there are many types of antennas to choose from but a few fundamental questions should be asked first. Do you want local communications or go DX’ing? Do you want omni-directional coverage or use a beam antenna. Let’s start with the basics. Convention dictates that FM based local communication traffic (voice and digital) uses vertical polarisation. The DX transmission modes of CW and SSB or a machine generated mode (MGM) such as FSK441 use horizontal polarisation. I’m not saying that you can’t use FM with a horizontal antenna, it’s just that the vast majority of operators follow this simple convention.
If you want local communications (possibly for an FM natter-net) then you will probably need omni-directional coverage. A simple vertical dipole or vertical co-linear antenna is very popular for this type of general transmission. Locate it as high as you can, ideally above roof level. But don’t lose all your transmit power or received signals within the feeder. Spend as much as you can afford on low-loss coaxial cable, ideally nothing less than 10mm diameter.
If you want to work long distances (DX) on CW or SSB then you must have some form of horizontally polarised beam antenna. A Yagi of 6-9 elements or more is ideal. However as with any type of directional antenna you must also use a rotator. You might be able to locate a small Yagi and rotator onto a suitable chimney stack but be aware that this often puts your antenna at the same height as neighbouring television aerials. The reality is that if you want to go DXing on the 144MHz band you’ll need a substantial mast or tower, a good rotator and an excellent Yagi. Of course there is one other way and that is to operate portable from a local hill top. With a small pole and a directional beam you can work hundreds of kilometres even when running relatively low power. And it’s great fun.
Propagation Modes on 144MHz
If you operate exclusively with FM. equipment the only propagation that you will normally experience is a tropospheric mode. You may occasionally hear fixed stations or repeaters from slightly further afield. However if you use a weak-signal mode such as CW or SSB then you will experience the excitement of catching numerous propagation modes. These modes include tropospheric ducting, Aurora, meteor scatter (MS) and Sporadic-E (Sp-E) and will enable contacts to be made up to 2000 kilometres away and sometimes even further.
Keeping up-to-date about 144MHz
If you want up-to-date information regarding the 144MHz band, then take a look at these web sites.
Repeaters and Gateways: http://www.etcc.rsgb.org/
Amateur Satellites: http://www.uk.amsat.org/
Take a look also at the RSGB Contest Committee web site as this gives details of 144MHz activity contests that are held every month.
If you have any suggestions regarding the 144MHz band plan please contact the VHF Manager.