Measurements on Tower supported Umbrella Aerial

The first configuration is with just two top-load wires, The natural resonance of the aerial was measured as 1280kHz. The lengths of each of the two top wires was approximately 30m

Frequency
in kHz		 Capacity
in pF		 Resistance
in ohm
122 546 18.6
136 546 19.2
150 548 18.2
220 559 15.3
300 576 12.8
400 611 10.3
500 662 12.1
600 730 12.5
822 1164 12.1

The next configuration was with two extra top-loading wires, making four. The natural resonance came down to 998kHz

Frequency
in kHz		 Capacity
in pF		 Resistance
in ohm
122 756 13.4
136 755 12.6
150 755 12.6
220 778 11.4
300 810 9.3
400 870 8.0
500 969 8.8

Then a further topwire was added to make five, leading to a natural resonance at 878kHz.

Frequency
in kHz		 Capacity
in pF		 Resistance
in ohm
122 936 12.6
136 939 12.8
150 932 12.6
220 969 11.8
300 1017 9.8
400 1118 8.2
500 1280 9.5

Finally the top-load was extended to five wires making the natural resonance 848kHz.. the remote ends of two sets of top-wires was connected together to forma bow-tie (see the spiral aerial page)

Frequency
in kHz		 Capacity
in pF		 Resistance
in ohm
122 1056 9
136 1050 9
150 1058 8.8
220 1100 10.9
300 1150 7.9
400 1300 7.9
500 1570 8.8

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