Beam-Splitting Condition in a Broadside Symmetric Leaky-Wave Antenna of Finite Length

In this letter, the influence of the truncation effects on the beam-splitting property of a broadside symmetric leaky-wave antenna (LWA) is presented. It will be shown that for finite length LWAs, the maximum broadside beam exists at higher phase constant values than suggested by infinite LWA analysis. The accurate beam-splitting conditions are obtained using a computer search algorithm and are reported for a range of practical LWA lengths. The behavior of the aperture distributions at the split conditions is then discussed. To illustrate the application of the result, the theoretical beam-splitting condition plot is used to identify the beam-splitting point of a microstrip based LWA design. Finally, other design implications of the findings are discussed.