Type of Feed	f/D Optimum	Best efficiency estimate	Measured efficiency for f/D=0.45	Comments
Chaparral	0.35-0.45	55-65%	61%	"11 GHz Superfeed" from Chaparral dealers good at 10 GHz
VE4MA / Kumar	0.35-0.45	55-65%	61%	proven performance at 1296, 2304, and 3456 MHz
W2IMU Dual-Mode	0.5-0.6	55-60%	NR	proven performance 432 MHz to 10 GHz
Rectangular horn	> 0.45	50-60%	58%	tailor dimensions for f/D - also good for Offset dishes
Clavin	0.35-0.4	50-60%	57%	small feed blockage
EIA Dual-dipole	0.5-0.6	50-60%	NR	better at lower frequencies
Circular horn	Function of diameter	25-50%	26%	asymmetrical E- and H-planes and phase centers; better with choke flange
Penny (G4ALN)	0.25-0.3	30-45%	41.5%	attractive mechanically
Dipole	0.3-0.4	30-45%	NR	asymmetrical E- and H-planes
Log Periodic	?	10-40%	14%	broadband, but poor phase centers

These recommendations are my best estimates for small dishes at 10 GHz,
and should be taken as my personal opinion.

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