An antenna's beamwidth is directly related to its overall gain, and effects the directivity. Directivity and beamwidth are worthy considerations when selecting an antenna for a site. Antennas with wide beamwidths are best suited when attempting to capture signals from more than one direction. When interference from the sides is a problem, a narrow beamwidth antenna is best. The best way to determine the output of an antenna is with a field-strength meter.
Meters can be real time savers when it comes to optimizing mounting height and aiming.
Unfortunately, meters are very expensive and few custom installers own one. The next best thing is to use a small battery-powered color TV so that roof or remote positioning can be monitored. Because of custom installers' client base, aesthetic requirements more often than not preclude large or visible antennas that may impose upon the architectural integrity of the home. This prerequisite can make antenna integration very difficult given that in large-money systems picture quality is essential to earning a referral. Fortunately, some manufacturers have introduced products that address the needs of the custom installer.