Vertical whip antenna
Description
The vertical whip antenna is omnidirectional in performance, therefore it provides radiation efficiency equally in all directions depending on its mounting position. When receiving, this omnidirectional performance may mean more unwanted signals are picked up, which contributes to high levels of background noise or interference.
Where used
The vertical whip antenna is designed for installation on buildings or open ground. The antenna is suitable for most transceivers operating with an associated antenna tuner.
Installation
The vertical whip antenna is designed for permanent or temporary installation. The antenna is easy to install.
For efficient operation of the vertical whip antenna, a good earth system is necessary.
When the antenna is erected on open ground, especially in dry ground conditions, an earth mat consisting of at least four wire radials extending as far as possible from the base is desirable (see page 49, Grounding the antenna).
For roof-mounted installations, metal roofing or a radial earth plane is recommended (see page 49, Grounding the antenna).
NOTE All antennas are supplied completely assembled and ready for installation.
Advantages and limitations
End-fed broadband antenna
Description
The end-fed broadband antenna is a multifrequency antenna.
Where used
The end-fed broadband antenna is designed for rural outposts, not built-up areas.
Installation
The end-fed broadband antenna is easily and permanently installed. It requires masts and sufficient space for installation. No installation or operational adjustments are required.
Advantages and limitations
Table 8: Advantages and limitations of the vertical whip antenna
Advantages Limitations
Suitable for long distance communication.
Omnidirectional antenna, therefore it can pick up signals equally in all directions.
Suitable where space is limited.
Unsuitable for distances under 100 km (60 mi).
This antenna is more susceptible to noise pickup such as that produced by welders, electric motors, power lines etc. If installed in a noisy environment, degradation of the received signal will occur.
Due to its relatively small size, it may require an antenna tuner for optimum performance.
Table 9: Advantages and limitations of the end-fed broadband antenna
Advantages Limitations
Wide operating frequency range.
Suitable for point-to-point and base-to-mobile applications.
Must be positioned at right angles to the desired direction of communication.
Due to its large size, it requires a large area for installation.
Due to its broadband properties, it has a low immunity to noise.
Broadband dipole antenna
Description
The broadband dipole antenna is designed for large-scale professional fixed station systems. The antenna is suitable for high or low power, multifrequency operation.
Where used
The broadband dipole antenna is designed for installation on buildings or open ground.
Installation
The broadband dipole antenna is generally erected on masts and requires sufficient space for installation.
Advantages and limitations
Long wire antenna
Description
The long wire antenna is suitable for multifrequency operation with most transceiver systems with an antenna tuner. It is approximately 20 m (22 yd) in length.
Where used
The long wire antenna is used on buildings or open ground. It is ideal for field crews who require an antenna that can be quickly and easily installed at temporary sites. It may also be used in permanent installations where space is limited.
Table 10: Advantages and limitations of the broadband dipole antenna
Advantages Limitations
Wide operating frequency range.
Generally, more efficient than the end-fed broadband antenna.
Suitable for point-to-point and base-to-mobile applications.
Must be positioned at right angles to the desired direction of communication.
Due to its large size, it requires a large area for installation.
Installation
The long wire antenna is designed for permanent or temporary fixed station installations.
It requires at least one mast and sufficient space for installation.
Advantages and limitations
Quick-to-erect dipole antenna
Description
The quick-to-erect dipole antenna is lightweight and portable. The antenna is designed for sky-wave communications over medium to long distances.
Each half of the antenna is marked in 0.5 MHz spacings wound onto the winding spool/
insulator. These elements unwind to the marker that indicates the frequency in use and clips into the slot provided on the insulator assembly. The remaining wire is short circuited on the reels.
Where used
The quick-to-erect dipole antenna is primarily used with manpack or portable HF systems.
Installation
The quick-to-erect dipole antenna is designed for temporary installations. The antenna is usually suspended between two trees or lightweight masts by terylene halyard tails with lead-weighted ends, which are supplied with the kit.
Table 11: Advantages and limitations of the long wire antenna
Advantages Limitations
Wide operating frequency range.
Large in size, therefore, is more efficient.
Must be positioned at right angles to the desired direction of communication.
Due to its large size, it requires a large area for installation.
The length of the wire may be too long for some operating frequencies and tuners.
Under these conditions, the length of the wire must be reduced according to the recommendations provided in the handbook for the tuner. If you require further assistance, contact your Codan representative.
Advantages and limitations
Dipole antenna
Description
The dipole antenna is a single frequency antenna that is manufactured to a particular length corresponding to its operational frequency. The antenna is designed for sky-wave communications over medium to long distances.
Where used
The dipole antenna is used on buildings or open ground.
Installation
The dipole antenna is erected on masts and requires space for installation.
Advantages and limitations
Table 12: Advantages and limitations of the quick-to-erect dipole antenna
Advantages Limitations
Easy and quick to install.
Lightweight and portable.
Must be positioned at right angles to the desired direction of communication.
Single frequency operation.
Table 13: Advantages and limitations of the dipole antenna
Advantages Limitations
Good signal quality.
Suitable for medium- to long-distance communications.
Single frequency operation.
Must be positioned at right angles to the desired direction of communication.
Due to the antenna requiring support at each end, greater space is required for installation.
Multiple dipole antenna
Description
A multiple dipole antenna consists of a number of dipole antennas supported on the same mast. Each dipole antenna corresponds to a different frequency. An antenna selector is required to ensure that the correct antenna is automatically selected by the transceiver for the particular channel in use.
Where used
The multiple dipole antenna is designed for installation on buildings or open ground.
Installation
The multiple dipole antenna is erected on a mast and requires space for installation.
For maximum efficiency, install:
• the lower frequency antenna above the higher frequency antenna
• adjacent antennas at least 2 m (2 yd) apart
Advantages and limitations CAUTION
Do not install antennas on the same mast if they are:
• tuned to frequencies closer than 10% of each other
• 3, 5 or 7 times the frequency of each other
Table 14: Advantages and limitations of the multiple dipole antenna
Advantages Limitations
Wide operating frequency range.
Large in size, therefore, is more efficient.
Must be positioned at right angles to the desired direction of communication.
Due to its large size, it requires a large area for installation.
Multichannel helical dipole antenna
Description
The multichannel helical dipole antenna has a maximum capacity of three operational frequencies. The narrow bandwidth of the antenna provides improved receiver
selectivity and noise reduction compared to the broadband antenna.
The antenna is available in two sizes:
• 4.5 m (5 yd)
• 7.5 m (8 yd)
The 7.5 m antenna is more efficient.
Where used
The multichannel helical dipole antenna can be used in locations where space is not available for conventional dipoles. It is often used on the rooftops of high-rise buildings.
The antenna is suitable for installation in noisy environments.
Installation
The multichannel helical dipole antenna should be mounted no higher above the ground than half the wavelength of the highest frequency used. The antenna must be correctly set up and adjusted by a technician on installation.
Advantages and limitations
Table 15: Advantages and limitations of the multichannel helical dipole antenna
Advantages Limitations
Provides better noise reduction compared to the broadband antenna.
Narrow bandwidth improves receiver selectivity.
Requires less space than a conventional dipole.
No antenna selector is required.
Must be positioned at right angles to the desired direction of communication.
Limited frequency operation.