RW4HFN Limited Space Balcony Dipole  Antennas

RW4HFN Limited Space Balcony Dipole Antennas

By: Igor Vakhreev, RW4HFN

If your antenna room is limited by balcony or attic you need think about a small antenna. Below you find a description of small antennas for HF amateur Bands 40- 10- meter.

There is a family of shortened dipole antennas with spiral loads on the ends. However the antennas can provide good result on the bands.

Figure 1 shows design of the shortened dipole antenna with spiral loads for the 10 meter band. MMANA file for the antenna you may download at:

http://www.antentop.org/023/RW4HFN_023.htm

Figure 2 shows SWR of the antenna. Figure 3 shows DD of the antenna. As you can see DD of the shortened antenna is almost similar to DD usual dipole antenna, so it is not shown for others antennas.

Figure 1 Design of the Shortened Dipole Antenna with Spiral Loads for the 10 meter Band

Spiral loads of the antenna made like a rectangle, distance between sides is 10- cm, first horizontal and vertical side is 10 cm long, then sides grow according to winding. Antennas for 30- 10- meter Band were simulated with length in 2- meter, main vibrator was simulated from aluminum tube in diameter of 16- mm, gamma match simulated from aluminum tube in diameter of 10- mm. Distance between vibrator and gamma match is 10- cm.

Spiral loads may be made from aluminum or copper wire in 1- 2- mm diameter. Antenna may be tuned in usual way- with length of gamma match and capacitors (match the input impedance) and with length of the spiral load (tune to resonance).

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