1. June, 2006 ASC presentation Design of Arrays with Minimum Side Lobes Leonid Kogan National Radio Astronomy Observatory

2. June, 2006 ASC presentation List of some arrays planned in soon future. ALMA Atacama Large Millimeter Array. 64 of 12 meter dishes Chile. Altitude >5000m SKA Square Kilometer Array EVLA Expanded VLA Most compact E-configuration NMA (New Mexico Array) DSN 100 of 12 meter dishes ATA Allen Telescope array of SETI 350 of 6.1 meter dishes LWA Long Wavelength Array ~40 antenna stations of 256 dipoles each

3. June, 2006 ASC presentation Which side lobes to optimize: Positive or Negative?

4. June, 2006 ASC presentation

5. June, 2006 ASC presentation Q1. Where should each array antenna move to decrease the value of the array beam pattern (Point Spread function - PSF)? Q2. How much should each of the array antennas move along the found direction to decrease the value of the array beam pattern (Point Spread Function - PSF) at the given direction?

6. June, 2006 ASC presentation Where to move antennas?

7. June, 2006 ASC presentation How much should an array antenna move along the found direction? The derivative of the function by determines how far is the antennafrom the optimum Therefore the required shift of the given antenna Is proportional to the relevant derivative:

8. June, 2006 ASC presentation The AIPS task CONFI CONFI can design an optimum configuration using multi iteration process. The direction toward the biggest side lobe is found on each iteration. The algorithm described above is used at each iteration. gain which should be small (<<1). Each antenna is moved by a small portion of the calculated value determined by the input parameter gain which should be small (<<1). The topography constrain, minimum spacing, bound of the configuration, several initial configurations and many other features are available.

9. June, 2006 ASC presentation An ALMA Largest Configuration Optimized with Matching the Terrain at the Chajnantor Site(Chile)

10. June, 2006 ASC presentation Alma compact configuration optimized having topography file of the roads. The side lobes optimized inside of a part of the primary beam. Maximum side lobe ~0.009

11. June, 2006 ASC presentation EVLA compact configuration. The size of the dots (red are existing pads) shows the antenna diameter 25 meter. The side lobes are optimized inside of the primary beam. Maximum side lobe ~5%.

12. June, 2006 ASC presentation SKA antenna station. The antenna diameter 12 meter. The side lobes are optimized inside of the primary beam. Maximum side lobe ~3%

13. June, 2006 ASC presentation DSN array 120 of 12 meter dishes Side lobes ~25db

14. June, 2006 ASC presentation LWA antenna station with 256 dipoles. Minimum spacing 2m. The area of optimization is the whole semi-sphere. The side lobes are less than 0.0056 (22.5dB)

15. June, 2006 ASC presentation Slice of the above beam pattern along DEC

16. June, 2006 ASC presentation Slice of the above beam pattern along RA

17. June, 2006 ASC presentation LWA antenna station with 256 dipoles. The beam pattern is phased toward zenith angle 60, azimuth 45.