The 50 ohm rectangular loop

Square loops have feed impedances in the range of 200 ohms, but stretching the loop vertically will decrease the feed impedance (when the feed point is in the middle of the short side). By choosing the right vertical to horizontal dimension¬†ratio it is possible to achieve a perfect 50 ohm match. This simulation was performed with MMANA GAL basic at 14.150 MHz, rectangle dimensions are 3.9 x 7.37 m, lowest point of antenna 2 meter above real ground, antenna is made of 1.5 mm diameter copper wire. It’s obvious that changing parameters, for example antenna height above ground, or simulating it in free space would change results.

rect loop 50 ohm

The radiation pattern is directional, with maximum radiation orthogonal to the loop plane while maximum gain is 6 dBi at 35.9 degrees.

rect loop lobe

 

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