Mobile communication antennas should have:
This means that most of the available signal should radiate equally well in all directions along the horizon. There are five key reasons why antenna systems can produce distorted (bad) radiating patterns and poor VSWR.
1. Design
Buy a suitable antenna which has a proven, efficient design.
Select the most suitable type of antenna available for the application. This means you should consider: frequency band; bandwidth; gain; the installation environment; and other end-user requirements. (See How do I choose?)
Buy from a manufacturer that has validated the design using test equipment in an anechoic chamber.
A design based simply on calculated measurements will be crude and the manufacturer will not have checked that the radiating pattern is good in ALL directions along the horizon.
2. Position & Angle
Position the whip: vertically; as high as possible.
If the antenna is tilted, some of the signal will be wasted because it will be directed up to the sky or into the ground. (see Glossary: Directivity)
If the antenna is lower than the vehicle's roof, the signal will be blocked and the radiating pattern will be distorted.
3. Material
Use a cable assembly of the correct length with properly fitted connectors.
Excess lengths of cable will increase attenuation. Coiled or knotted cable can cause interference. The most common cause of poor equipment performance is incorrectly fitted connectors or poor quality cable assemblies.
(Panorama's coaxial cable has good 'low loss' characteristics) (See cable specification)
4. Ground Plane
Follow the manufacturer's instructions and good electrical engineering practice - should be ½ wave diameter as minimum size.
If the ground plane is unsuitable or too small, panel mount antennas could fail to perform efficiently.
(See Glossary: Ground plane )
5. Obstructions
Fit the antenna as far away from obstructions as possible.
Obstructions close to the antenna can block the path of the signal, or effect the tuned resistance.