How Long Should the Antenna Be?

If you have the room to install an external passive antenna inmost cases it should outperform most active antennas we've tested.But how long should the antenna be? The amateur radio antennahandbooks don't include measurements for the SWL tuning to thebroadcast bands. The books show you how to build passive antennas,and we have done the work for you to convert the antenna lengths.The figures in the tables below are calculated upon the mid-pointsof the broadcast bands.

World Broadcasting Bands (including WARC extensions)

The antenna wavelengths below are expressed in meters, roundedto the nearest one-tenth of a meter.

Meters	MHz	kHz	One-quarter	Half	Three-quarter	One
------ Antenna Length -------
120	2	2300-2495	29.7	59.4	89.2	118.9
90	3	3200-3400	21.6	43.2	64.8	86.4
75	4	3900-4000	18.0	36.1	54.1	72.2
60	5	4750-5060	14.5	29.1	43.6	58.1
49	6	5900-6200	11.8	23.6	35.3	47.1
41	7	7100-7350	9.9	19.7	29.6	39.4
31	9	9400-9990	7.3	14.7	22.0	29.4
25	11	11600-12100	6.0	12.0	18.0	24.1
22	13	13570-13870	5.2	10.4	15.6	20.8
19	15	15100-15800	4.6	9.2	13.8	18.4
16	17	17480-17900	4.0	8.1	12.1	16.1
15	19	18900-19020	3.8	7.5	11.3	15.0
13	21	21450-21750	3.3	6.6	9.9	13.2
11	26	25600-26100	2.8	5.5	8.3	11.0

In some parts of the world, measurements are not (yet) metric.To help you, the antenna wavelengths below are expressed in feet,rounded to the nearest one-half of a foot.

Meters	MHz	kHz	One-quarter	Half	Three-quarter	One
------ Antenna Length -------
120	2	2300-2495	97.5	195.0	293.0	390.5
90	3	3200-3400	71.0	142.0	212.5	283.5
75	4	3900-4000	59.0	118.5	177.5	237.0
60	5	4750-5060	47.5	95.5	143.0	191.0
49	6	5900-6200	38.5	77.5	116.0	154.5
41	7	7100-7350	32.5	65.0	97.0	129.5
31	9	9400-9990	24.0	48.5	72.5	96.5
25	11	11600-12100	19.5	39.5	59.0	79.0
22	13	13570-13870	17.0	34.0	51.0	68.0
19	15	15100-15800	15.0	30.5	45.5	60.5
16	17	17480-17900	13.0	26.5	39.5	53.0
15	19	18900-19020	12.5	24.5	37.0	49.5
13	21	21450-21750	11.0	21.5	32.5	43.5
11	26	25600-26100	9.0	18.0	27.0	36.0

Coaxial cable

Observations on passive antennas

Building your own antennas?

Active Antennas

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