Preeti and Roopa were looking up reasons for which the antenna might not be working at the desired frequency. They came across this fact on this page.
The length of a dipole is the main determining factor for the operating frequency of the dipole antenna. Although the antenna may be an electrical half wavelength, or multiple of half wavelengths, it is not exactly the same length as the wavelength for a signal travelling in free space. There are a number of reasons for this and it means that an antenna will be slightly shorter than the length calculated for a wave travelling in free space.
Antenna length
Hence, we feel that we have actually used a longer length than necessary...giving us a smaller frequency at 72 MHz. We will try reducing the length tomorrow and checking.
Also regarding the impedance matching..a Sleeve Balun is commonly used in VHF range. You can find more details on this page .
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