From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Guide on the principles of installing a car radio, with a focus on aerial selection and placement.
| Identifier | ExFiles\Box 168b\1\ img263 | |
| Date | 21th May 1940 guessed | |
| Part I Installing of car radio. The installing of a car radio may at first appear to be a very simple operation but when one gives a little thought & examination to the job in view it will be realised that the first impressions were very misleading. There are no hard & fast laws governing this type of installation mainly on account of the different types of receivers & their relative sizes & methods of fixing to the car, however there are some very salient points which if carefully followed will justify their execution. The first & main point is the choice of an aerial & its installing. no matter how good the receiver may be unless it is connected to an efficient aerial, all its effectiveness will be lost. [The following paragraph is crossed out with a large diagonal line] Before proceeding any further if the fundamental principals of reception of radio signals were understood it would greatly facilitate this fitting. Waves radiated from a broadcast station impinge on the aerial & create a difference of potential between it & the earth, this causes a current to flow in the aerial which is direct proportional to the length & height of the aerial & to the strength of the passing waves. In other words the best reception is obtained when the largest possible aerial is used at its greatest height from earth, the earth in our case being the metal work of the car & the distance between it & the aerial is referred to as the "effective height" of the aerial. It will thus be seen that careful attention must be paid to securing the maximum "effective height" irrespective of the type of aerial used. | ||