Antenna calculation

Formulas for Dipole and Vertical Antennas

Half-wave antenna in free space (15006 / F)	cm
Practical half-wave antenna (up to 30 MHz) (14274 / F)	cm
Half-wave antenna (50 to 144 MHz) (14030 / F)	cm
Half-wave antenna (above 144 MHz) (14233 / F)	cm
Quarter-wave antenna (7137 / F)	cm
Full-wave antenna length (30653 / F)	cm

Enter frequency (MHz):

J-Pole Antenna Calculator

	A = cm
	B = cm
	C = cm (Feedpoint Z = 50 Ohms)
	D = cm

Enter frequency (MHz):

"Cubical Quad" Antenna Calculator

Antenna with a tuning stub (Variant A)
Length of each loop side (7564 / F)	cm
Distance between loops A (3599 / F)	cm
Antenna with a closed-loop reflector (Variant B)
Driven element side length (7625 / F)	cm
Reflector side length (7869 / F)	cm
Distance between loops A (3599 / F)	cm

Enter frequency (MHz):

Yagi-Uda Antenna Formulas

2-element Yagi (Variant A)
Driven element length (14518 / F)	cm
Director length (13725 / F)	cm
Distance between elements A (3660 / F)	cm
3-element Yagi (Variant B)
Driven element length (14426.5 / F)	cm
Reflector length (15280.5 / F)	cm
Director length (13572.5 / F)	cm
Distance between elements A (7137 / F)	cm

Enter frequency (MHz):

Y-Match System for Yagi Antennas

Band, m	Match tube length L, cm	Distance A, cm	Max capacitance of variable capacitor C, pF
2 10 15 20 40	16.5 80 120 170 300	2 10 14 16 22	18 50 80 150 250

Note: The table provides approximate data for a Y-match system. These values are valid only if the antenna's input impedance is between 15 and 30 Ohms and matching is done with a coaxial cable of 50...70 Ohms characteristic impedance.

HF Vertical (Ground Plane) Calculator (1-50 MHz)

Vertical radiator length: cm Length of each radial: cm Minimum number of radials is 4. The antenna impedance is approximately 30-45 Ohms, depending on the number of radials, their tilt angle, and height above the ground.

Enter frequency in kHz (e.g. 14160, 3650):

VHF/UHF ¼λ Vertical (Ground Plane) (100-500 MHz)

Vertical radiator length: mm Length of each radial: mm Number of radials is 4. Radials are tilted downwards at a 135° angle to achieve a perfect 50 Ohm feedpoint impedance.

Enter frequency in kHz (e.g. 145500, 433025):

HF Dipole Calculator (1 to 50 MHz)

Total wire length: cm
Impedance: 50-80 Ohms	Length of one leg: cm

Recommended mast height is not lower than m and not higher than m from the ground/roof. Below the recommended height, the antenna radiates mostly straight up (NVIS); above the recommended height, the radiation pattern splits into narrow lobes.

Enter frequency in kHz (e.g. 3650, 7100):

HF Windom (Off-Center Fed) Calculator (1-50 MHz)

Total wire length: cm
Feedpoint Z: ~500 Ohms	Short leg length: cm

The feedline drops at an arbitrary length. The antenna impedance highly depends on the suspension height, spatial layout, and exact feedpoint position. An Antenna Tuner (ATU) is absolutely required!

Enter frequency in kHz (e.g. 7060, 14160):

HF Inverted V Calculator (1-50 MHz)

Feedpoint Impedance: ~50 Ohms
Total wire length: cm	Length of one leg: cm

The length and impedance of an Inverted V are slightly less than those of a standard dipole because the legs slope towards the ground. Recommended mast height is not lower than m and not higher than m.

Enter frequency in kHz (e.g. 7050, 3650):

HF Loop (Quad/Delta) Calculator (1-50 MHz)

Impedance: 75-120 Ohms

Total wire length of the loop: cm.

A Delta loop is convenient to hang between multi-story buildings. The sides of the triangle can be of different lengths. Recommended suspension height of the top point is not lower than meters from the ground (or roof).

Enter frequency in kHz (e.g. 1890, 7100):

VHF/UHF Vertical Dipole (100-500 MHz)

Leg (tube) length: mm Requires 50 Ohm coax. The structure consists of two hollow tubes separated by an insulator. The coaxial cable runs up through the inside of the lower tube to the center. The center conductor connects to the upper tube, and the shield connects to the lower tube.

Enter frequency in kHz (e.g. 145500, 433500):

↑ Top | Home