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RAF MF and HF Aerials 1940s to 1970s.

The Delta matched Horizontal Single Wire Half-wave Dipole.

The Three-wire Folded Half-wave Dipole.

The three-wire folded dipole was used by the RAF as both a receiving and transmitting aerial. The band width is greater than that of a single-wire dipole due to the greater cross-sectional area of the aerial which resulted from the folding. The folded dipole had a greater capacitance and less inductance per unit length than the basic dipole. This type of folded dipole can be regarded as a normal dipole with an extra half wavelength of wire added on to each end, these extra lengths being folded back parallel with the centre portion to form three closely spaced parallel dipoles. The current standing waves in the three portions are in phase and the radiated waves reinforce each other. The feed impedance of the aerial is about 600 ohms and thus could be connected to the standard open wire feeder systems. The aerial elements were constructed using 100lb per mile copper wire.

The Eight-wire Cage Full-wave Dipole Aerial.

The eight-wire cage full-wave dipole aerial was widely used by the RAF for both transmitting and receiving. The cage form of the aerial gave it a greater bandwidth than a single wire aerial and also gave it a greater power handling capability. Its feed impedance of about 600 ohms enabled it to be connected to the standard RAF open wire feeder systems. The aerial elements were constructed using 100lb per mile copper wire.

The Eight-wire Cage Quadrant Aerial.

The eight-wire cage quadrant aerial was simply a standard eight-wire cage dipole which was bent at the centre until the two halves are at right angles. This action changes the aerial from a directional aerial into an omni-directional aerial. Its feed impedance remained the same at 600 ohms. The two quadrant cages were constructed at slightly less than a half-wave long using 100lb per mile copper wire.

Vertical HF Aerials.

Single wire vertical aerials were in common use throughout the RAF as they were simple to construct and did not occupy a large amount of ground space. They were used for both transmitting and for receiving. The most frequently used aerial length was the 1/4 wave length aerial as it could be fed directly using a co-axial cable. The aerials could range from 1/8 wave to 5/8 wave length but these aerials needed an open wire feeder system and matching stubs. Some aerials were completely vertical and others had the top turned in a horizontal direction.

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