Kenwood TS-780 manual 4- 1. ANTENNA

4- 1. ANTENNA

The Performance of the transceiver depends upon the type of antenna to be used. To ensure the maximum perfor- mance of the TS-780, select a suitable antenna and adjust it for the best condition.

Common Antenna for 144/430 MHz Operation

The TS-780 is designed so that two different transmit Outputs (144 and 430 MHz) are supplied to individual antennas. Use of individual antennas is recommanded as it simplifies the antenna matching and minimizes the loss cuased by antenna. However, if it is desired to use a com- mon antenna, available from market, because of installa- tion conditions, etc., it should be properly adjusted and connected by carefully following the instruction manual furnished with the antenna. An example of connection of a common antenna is illustrated in Fig. 4.

Notes:

1.A common antenna should be connected through a dividing filter (some types of common antenna have built-in dividing filter).

2.An antenna selector (up to 430 MHz) may be used in lieu of a dividing filter.

3.Never attempt to connect a common antenna without using a dividing filter.

TS-780	144 MHz cable		Dividing filter	Antenna
	4 3 0 M H z cable	L		cable

Fig. 4 Connection of Common Antenna I

Type of Antenna

Choose a proper antenna according to whether it is used for fixed Station or mobile Station Operation. For fixed sta- tion Operation, a Yagi antenna (directional type) or a ground plane antenna (omnidirectional type) is recommended.

Antennas for fixed Station Operation should be installed observing the following three conditions:

•Selection of Antenna

Choose an antenna suitable for the purpose of use, budget and installation location.

In general, a beam antenna such as Yagi antenna is suitable for Operation with DX stations or a specific sta- tion, and a ground plane omnidirectional antenna for Operation with local stations. In the case of Yagi anten- nas, use of a stacked type antenna as shown in Fig. 5 will provide excellent directivity and RF gain.

•Installation Location

For satisfactory DX Operation, the antenna should be in- stalled as high as possible. An example of a good loca- tion for the installation of antenna is on a hill such as il- lustrated in Fig. 6, “A” Station.

Installing as antenna in such a high location allows reception of many stations; however, this often creates a possibility of radio interference. Therefore, it is recom- mended that a stacked type directional Yagi antenna be used for satisfactory DX Operation.

The “A” Station on the hill provides better transceive opera- tion than the “B” Station if the same type of antenna is used.

Fig. 6 Good Location for Antenna Installation

Directivity of “E” Station

Ground plane antenna (omnidirectional)

Directlon of *beam.

“A” and “C” stations are transmitting with the same frequency, while “B” and “D” stations are receiving the Signal. In this case, radio interference is very little.

However, if “E” Station is transmitting with the Same freauencv and “A” and “C” stations are receivinq the Signal, interference will possibly occur.

In areas crowded with many stations. it is recom- m e n d e d t h a t a b e a m a n t e n n a b e used. as i t eliminates interference when those stations are transmltting with the Same frequencv.

Fig. 5 Antenna Directivity

(The Pattern Shows an Ideal condition. In practice, this pat- tern becomes complex because it is influenced by surroun- ding buildings and geographical features.)