A revised attempt at simulating the Miracle Whip plus three counterpoises situated in a 2nd floor room oriented such that its north wall is in a plane at 70 deg. East of North (using Compass Bearing Angle Convention, the Y axis is True North, 0 deg.). The Miracle Whip stands leaning in the NW corner about 5' aff or 18' ag. A 16' counterpoise (coax braid of feedline) drops to the floor and runs along the north (inside) wall to the transceiver (Wires 2 & 3). A 10' counterpoise arcs along the west (outer) wall to the floor (Wire 4). A 30' counterpoise drops to the floor and runs through the door at the diagonally opposite corner into the hallway with an additional bend not shown along the south (outer) wall. This was the setup that grew progressively from 1 counterpoise to 3 during Jan 14-23, 2009.   

This model employs an emulation of the impedance transforming, base loading and inherent loss of the CVAT autotransformer using parameters looked up in the table in "EZNEC Simulation of Miracle Whip Antenna and Extensions". The reader is directed to the aforementioned article and to the Antenna Notes associated with the EZNEC model "MiracleWhip on transmitter.ez" for more information on the CVAT emulation.

At and above 18MHz EZNEC 5.0 Demo reports segmentation warnings that will further degrade accuracy; a full EZNEC license is required for finer segmentation. Of course, nothing has been factored in for the influences of household wiring, eavestroughing, downspouts, soffits, and snow and ice on the roof. Nonetheless, the radiation patterns are interesting and may account in part for successful contacts on 80, 40, 30m and 20m. 

Wire #1 is nominally the 57" whip, increased to 73" to compensate for the feed insertion (the L-networks object) at 25% from the end and simplified to a constant 1/4" diameter. The simulated counterpoises below the source include ~15" split off from Wire 1 so the remaining counterpoise Wires have been reduced in length to compensate. Wires 2 & 3 form the 1/4 wave@20m counter-poise or lower half of the dipole which is nominally 16 ft. including the 15" from Wire 1.  The actual 20m counterpoise is the radiating braid of the coax feedline with a common-mode choke at the 1/4 wave distance from the Miracle Whip input. The other counterpoises were readily available wires near what I thought would be desirable lengths (1/4 wavelengths for 15m and 40m), simply clipped to the golf ball retriever to which the Miracle Whip is attached and the coax shield bonded.

EZNEC 5.0 Demo is limited to 20 Wire segments and these were distributed among the wires so that each segment is on the order of the same length. Insertion of the feed renders 1 segment into two smaller segments. Because the total wire length is approximately 61', the average segment is about 3', hence the  whip was allocated only 2 and the 20m 1/4 wave below was given 6 total, 2 for the vertical wire, 4 for the horizontal.

No claim can be made for the accuracy of the model. It has been neither sanctioned by nor validated by Miracle Antennas, the manufacturer of the Miracle Whip. The model is purely the invention of the author who shall not be held liable for any loss or damage that may ensue from anyone's use of the model or from the application of changes to the Miracle Whip antenna that may appear to work in the model. 

Tom Holden
VE3MEO
5 Feb 2009