Marine HF Radio Antennas, 2 to 30 MHz
This selection of marine HF antennas are designed to couple with your HF radio transmitter via an Antenna Tuning Unit (ATU).
The ATU will match the impedance of your HF radio to the antenna and feeder cable, which in this case will be 50 ohms.
Since tuning limits are determined by the ATU, clients contemplating purchase of these antennas should verify in advance that their ATU specification will load the given length of radiator for the chosen antenna model at the lowest frequency desired.
Mast or Side Mount HF Antenna Models HM218/M and HM223/M
Models HM218/M and HM223/M are suitable for all HF marine communications in the 2 to 30 MHz frequency range. These longer antennas offer top performance together with a two-piece light weight construction enabling easy dismantling and storage.
- HM218/M stands 6 metres tall when fully assembled and can handle up to 500 watts input power.
- HM223/M is taller at 8.1 metres and is rated for 1,400 watts power.
The two-piece white fibreglass radome is fully sealed and packed tight with closed cell foam to protect the internal braided copper radiator, prevent rattles and maximise service life in harsh marine conditions.
The copper radiator terminates on a stainless steel stud above the mount tube, to which the 6 metre high voltage feed cable attaches. Mount tubes do not carry RF voltage.
To broaden your choice of mounting positions, both mast mount and side mount clamps are available.
For mounting to a mast, 2 x UAM180L galvanised steel parallel clamps are recommended for a round mast between 40 mm and 75 mm in diameter.
Side mounts are nylon and include ½"–BSW stainless steel fasteners. These allow easy mounting to the side of a wheelhouse or any other vertical flat surface. Order NSM218 or NSM223 according to the antenna model.
2 nylon side mounts are necessary. Drill a 12.7 mm (½") diameter hole through the wall for the stainless steel bolt and then firmly secure each side mount in position.
Deck Mount HF Antenna Model HM300 for large vessels
HM300 is a 10 metre tall free standing marine HF radio deck mount antenna specifically designed for larger vessels. This model delivers outstanding performance, is very durable and accepts high input power up to 2,000 watts PEP.
The antenna couples with a HF radio transmitter via an Antenna Tuning Unit.
The sturdy fibreglass radome is a three piece construction with each section joined with stainless steel ferrules. Each radome is fully sealed and packed tight with closed cell foam to protect the internal braided copper radiators, prevent rattles and maximise service life in harsh marine conditions.
The radome tip has a corona ball to prevent high voltage discharge into the atmosphere. The antenna butt is bonded to a short piece of stainless steel tube.
The deck mount base assembly is available to order separately if required. Constructed from stainless steel, this very sturdy deck mount plate is 300 mm in diameter and 12 mm thick. The vertical mount tube is welded to the steel plate. There are 4 holes in the plate for securing the base to the deck using stainless steel bolts, washers and nuts.
Termination is via a bolt in the base to which the 6 metre single core 20 kV antenna feed cable attaches.
Deck Mount HF Antenna Models HM212 and HM215
The HM212 and HM215 deck mount antenna models are suitable for all HF marine communications in the 2 to 30 MHz frequency range.
- HM212 is 3.7 metres tall.
- HM215 is 4.5 metres tall.
- Both antennas deliver 2.1 dBi gain and are rated for up to 250 watts power.
The single piece fibreglass radome is fully sealed and packed tight with closed cell foam to protect the internal braided copper radiator, prevent rattles and maximise service life in harsh marine conditions.
The copper radiator terminates via 5 metres of high voltage (20 kV) feed cable side exiting from the chromed brass mount ferrule.
Both models come complete with our highest quality fully stainless steel MM2 folding deck mount. This base folds down in two directions and also swivels in the opposite plane by loosening the stainless steel pivot bolt.
This versatility allows the antenna to be mounted in a variety of positions on any flat surface and at any angle using four screws or bolts.
The antenna must be in a vertical position for optimum performance and can be folded down when not required.
Installation advice for Marine HF Radio Antennas
To achieve best performance, the marine HF radio antenna must be mounted as far away from other antennas and metallic objects as possible to avoid interference and distortion of the radiation pattern. Also, a good earth system is the essential key to achieving the optimum transmit and receive performance.
The HF radio antenna must be isolated from the vessel's earth system. The antenna feeder cable attaches to your Antenna Tuning Unit, and it is the ATU which must be connected to the vessel's earth system. Refer to the installation instructions which came with your ATU.
The vertical radiation pattern for these HF radio antennas is largely influenced by the size, shape and nature of the ground plane under the antenna. Symmetrical, balanced, as well as low resistance earthing is needed for a good omnidirectional radiation pattern.
The length and placement of the feedline also has a large effect on pattern formation, with modelling indicating a long feedline at right angles to the antenna causes the pattern to vary greatly from omnidirectional.
Keep all leads as short as posible and joints in the earth system fully soldered. Earthing system problems may also cause the DC feed wiring to become an active radiator.
Routing the Feeder Cable
Route the cable carefully to your HF radio. Ensure that the cable is not stretched excessively and there are no sharp kinks.
If using cable ties, then we highly recommend the stainless steel type for the harsh marine environment.
Do not pull the cable ties so tight as to crush the cable. A damaged feeder cable is a cause of high VSWR and reduced performance.
Sealing Connections
For the marine environment, it is vital that all connections be well sealed with at least two layers of self-amalgamating tape. PVC or electrical tape will not be adequate.
Maintenance
ZCG Scalar marine antennas have been designed for high reliability and low maintenance.
We recommend that you conduct a routine annual mechanical inspection of the antenna, feeder cable and connections.