In selecting an antenna for Radio Astronomy it is important to achieve a high degree of gain, low noise and have a a reasonable bandwidth for the frequency chosen.
After a review of many antenna designs, I have settled on a 16 Element Collinear Broadside Array as the most cost effective and high gain system to deploy on the 74Mhz band.
Element dimensions for 74Mhz
Each 1/2 wave feeder element = 1.948M
Each 1/2 wave reflector element = 2.064M
Spacing between feeder and Reflector = 0.771M
Overall dimensions = 6M X 4.2M X .771M
This is the basic electrical layout of the antenna it has balanced feed-line with an output impedance of between 300 to 400 ohms and an expected gain of 16dbi and a beam width of about 30 degrease.
Each element is made of aluminium tubing and can be mounted directly using a simple U-clamp to welded steel frame without insulators. Affixed in the centre of the 1/2 wave element the impedance is at its lowest, so an insulator is not required.
Collinear Broadside Arrays can also be connected in pairs simply, without the need of complex impedance matching networks.