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An antenna beam pattern gives an antenna's directional response as a function of observation angle. A normalized power pattern divides radiation intensity by its peak; a field-amplitude pattern is its square root under a consistent impedance convention. The beam solid angle integrates the normalized power pattern over direction, so ideal directivity is $4\pi /{\Omega }_A$. A short dipole antenna has a power pattern proportional to ${\sin }^2\theta$, zero along its axis and maximum broadside. A narrow main lobe can coexist with sidelobes, so beamwidth alone does not specify the complete response.

A dipole antenna uses two conducting arms carrying an oscillating current, commonly fed across a central gap. Its changing charge and current distributions produce electromagnetic radiation. A short straight dipole has far-zone power proportional to ${\sin }^2\theta$ relative to its axis: it radiates most strongly sideways and has axial nulls. A practical half-wave dipole has a nonuniform current distribution and a different exact pattern and input impedance. Geometric wire length, electrical length and the surrounding dielectric or conducting structures all affect resonance and matching.

Jocelyn Bell Burnell helped build Antony Hewish's radio telescope for finding compact sources through interplanetary scintillation in the solar wind. Operating it and inspecting its chart recorder output in 1967, she recognized an unusual recurring trace, checked earlier charts, and obtained fast recordings resolving pulses in late November. Her observation, recognition and persistent analysis were indispensable.^[ref]

The 1968 paper by Antony Hewish, Jocelyn Bell Burnell (bylined S. J. Bell), J. D. H. Pilkington, P. F. Scott and R. A. Collins reported $1.337\mathrm{s}$ spacing and proposed compact-star oscillations. Its radio telescope had 2,048 full-wave dipole antennas in sixteen rows. Four receivers selected declinations; two array halves formed an east-west interferometer. The $81.5\mathrm{MHz}$ receivers passed $1\mathrm{MHz}$. Observations used $0.05\mathrm{s}$ receiver time constant and Rapidigraph chart recorder with $0.03\mathrm{s}$ time constant; radio second pips calibrated timing.^[ref]

Antony Hewish checked sidereal time recurrence. Jocelyn Bell Burnell recalls that P. F. Scott and R. A. Collins reproduced the pulses with another telescope and receivers, while J. D. H. Pilkington measured pulsar dispersion delay: independent checks of instrument independence and intervening plasma.^[ref]

A useful numerical comparison uses the approximate sidereal time day of $1436.07\min$. Relative to a $1440\min$ schedule, the same sky direction transits about $3.93\min$ earlier each day, or $39.3\min$ after ten days. This compares successive passages through the receiving beam; it is a different clock from the roughly $1.3\mathrm{s}$ pulse spacing within one passage. Sky recurrence alone cannot rule out every transmitter or reflection, and pulsar dispersion delay alone does not uniquely establish an emission mechanism. Their strength lies in independent constraints agreeing.

The discovery lesson is that an unexpected signal must survive changes of readout, instrument and observing date. Increasing chart recorder speed exposed structure hidden in a compressed trace; it did not make the source begin pulsing. The pulsar interpretation now separates the rotating clock, beam geometry, pulsar magnetosphere emission and pulsar dispersion delay. The initial observation established periodic arrival, not a direct measurement of the neutron star's surface motion or radius.