40M Mini-loop Antenna for QRP By Rob L. Dey, KA2BEO 1/24/99 Specifications SIZE: 4'W x 4'H x 0.5"D approx. FEEDPOINT IMPEDANCE: Balanced, 50-ohms approx. CENTER FREQUENCY: 7.200 MHz SWR: 1.1:1 BANDWIDTH (2:1 SWR): 300 kHz, 7.000-7.300 MHz POWER RATING: 15 W rms (QRP only), 150 W rms (if 5kV caps are used) TUNING: None required, pretuned design. GROUND: None required, balanced design. Also, no balun required for coax feed. MAINTAINANCE: None required, completely weatherproof. MOUNTING: Hang vertically in any convenient location, even in the basement. Feedpoint is at the top. RADIATION PATTERN: Major lobes in front and back at all elevation angles. Additional Features of a Small Tuned Loop * High selectivity increases dynamic range of receiver. * Sharp nulling can isolate stations apart by 10° to 170° with 60dB of attenuation or more. * Approximately 26dB of electrostatic noise reduction quiets man-made, precipitation, and other noise sources. Parts Required 16' 14/2WG Romex Cable 3 x 14 AWG 600V 2 PVC Strip 4"L x 5/8"W x 1/8"Thk (Drill one with a 3/8"D hole in center for BNC, and one with six holes for capacitors) 1 BNC Female Connector, lock-washer, solder lug, and nut 2 27pf ±5% 500V Silver-mica Capacitor or equiv. 1 33pf ±5% 500V Silver-mica Capacitor or equiv. 1 20pf ±5% 500V Silver-mica Capacitor or equiv. (Solder this cap across the 33pf cap, or use a 50pf variable capacitor across the 33pf cap) Solder Electrical Tape See the other 40-meter Mini-loop Antenna for any details that may be missing here. Use the above construction technique for 2' square, and 1' square loop antennas for 20-meters and 10-meters also. Capacitor values will need to change accordingly.