Caravan Antenna Feedback

In reply to Wilmo 17 Apr. Thankyou for your comment.

I would like to take up your comment regarding the yaggi antenna –many yaggi house antennas are sold into the caravan market with disappointing results. I have been involved in antenna design and testing for some 10 years now and can assure you that a yaggi antenna is frequency limited. A yaggi antenna has a series of directors out in front of a dipole. These directors are used to provide an increase in signal gain. You can design an antenna with many directors to give greater and greater signal gain over a small bandwidth or range of frequencies. You cannot of course get something for nothing.
The design gets its increase in signal gain as a consequence of the reduced number of frequencies it will work on. It is an observable fact for anyone interested in this subject. Just take a look at the house antennas as you travel around and you will see a great variation in the spacing and length and number of directors. With a house it is simple, you just choose the yaggi designed for the frequencies that the house will always be receiving. Put the house on wheels and drag it around the county and it is a very different story. You will encompass all frequencies. This is just physics. Sorry but wishing it were not so does not make it so. A yaggi antenna is a fine choice for a house or fixed van site.

This is not to say that you cannot get an antenna to work outside of its best efficiency area. You can of course and this is how we use rabbit ears or fixed length dipoles to work over a broad range of frequencies. Adding an amp will help this of course as you can help where the antenna is deficient. But if the frequency is too far from the efficient area of the antenna then it will not work well at all. You can see this with rabbit ears. How often have you lengthened them or shortened them to improve the picture. When it comes to indoor antennas you will find that the newer ones have a separate UHF antenna as the frequencies exceed the useable range of the rabbit ears. So this data is most likely already known to you from your own experience.

Wilmo also states that other considerations play a part in the choice of the antenna. Considerations such as compactness or ease of use or ability to mount vertically easily. These are valid and the article does not dispute any of them.

The article is a genuine educational article to help people understand that every antenna has compromises and that understanding them will help you get the best out of your choice.

As a point of interest however he states that the Aussievan antenna can be mounted vertically. As it has a rotator in the head of the antenna I do not see how it can be turned vertical. If you pushed the button it would be either looking at the ground or the sky. Or do you simply ignore the rotator when mounting it vertically? I am interested to know.

I have many educational articles on the explorer web site intended to help people understand the subject and get better results. From, "understanding digital" to articles on transmitters and VHF and UHF signals.

Happy caravanning
Regards Richard Henry