Beamwidth

In a radio antenna pattern, the half power beam width is the angle between the half-power (-3 dB) points of the main lobe, when referenced to the peak effective radiated power of the main lobe. See beam diameter.Beamwidth is usually but not always expressed in degrees and for the horizontal plane. In a radio antenna pattern, the half power beam width is the angle between the half-power (-3 dB) points of the main lobe, when referenced to the peak effective radiated power of the main lobe. See beam diameter.Beamwidth is usually but not always expressed in degrees and for the horizontal plane. The beamwidth can be computed for arbitrary antenna arrays. Defining the array manifold as the complex response of the m {displaystyle mathrm {m} } element antenna array as A ( θ ) {displaystyle mathrm {A} ( heta )} , where A ( θ ) {displaystyle mathrm {A} ( heta )} is a matrix with m {displaystyle mathrm {m} } rows, the beam pattern is first computed as: where A ( θ o ) ∗ {displaystyle mathrm {A} ( heta _{o})^{*}} is the conjugate transpose of A {displaystyle mathrm {A} } at the reference angle θ o {displaystyle heta _{o}} . From the beam pattern B ( θ ) {displaystyle mathrm {B} ( heta )} , the antenna power is computed as: The half power beamwidth (HPBW) is then found as the range of θ {displaystyle heta } where P = 0.5 P m a x {displaystyle mathrm {P} =0.5mathrm {P} _{max}} .