Antenna installation | Kenwood TS-440S guide

10.REFERENCE

10-1. Antenna installation

10-1-1. Fixed station

For HF fixed-station operation, an antenna specifically

designed for amateur operation is recommended. An- tenna types include wire antennas, verticals, rotary beams, and other antenna types. (Fig. 10-1) HF anten- nas are quite large and must be installed to withstand strong wind, heavy rain, etc.

Any antenna used with the TS-440S should be of 50-ohm impedance and should be connected using an appropriate coaxial cable such as RG-8/U.

Impedance matching is important. Impedance mis- matching will result in a high VSWR and power loss, or can cause unwanted harmonic radiation and inter- ference (TVI, BCI).

The impedance match can be checked with an SWR

meter. Generally, satisfactory operation is assured when the VSWR (Voltage Standing Wave Ratio) is less than 1.5: 1.

A rotary beam antenna is very effective for OX com- munication in the 14,21 and 28 MHz bands. (Fig. 10-2) If open wire or balanced type transmission line is used with the antenna, a suitable antenna tuner with balun is recommended between the transceiver and the feed

line. Methods of construction and operating such tuners are described in detail in the ARRL Antenna Handbook, or similar publications. For operation on the 160,75 and 40 meter bands, a simple dipole antenna, cut to resonance in the most used portion of the band,

will perform satisfactorily. For operation on the 10,15 and 20 meter bands, the efficiency of the station will be greatly increased if a good directional rotary anten- na is used. Remember that even the most sophisticat- ed transceiver is useless without a good antenna.

Ground plane antenna

Dipole antenna

Fig. 10-1

10-1-2. Mobile

(1) Antenna

Use a sturdy mount for the mobile antenna since HF antennas are larger (and have more wind load) and are heavier than VHF antennas. A bumper mount is recom- mended for general use. The ground side of the mount must be well grounded to the car body, since the body itself functions as the ground plane for the mobile an- tenna. (Refer to Fig. 10-4)

Notes:

1.Some cars have plastic bumpers. For such cars, ground the antenna mount to the body.

2.When tuning a newly installed antenna, use the fol-

lowing procedure:

.Turn the CAR control fully counter-clockwise for minimum transmit power.

.With the transceiver in transmit mode. raise transmit power output slowly by rotaing the CAR control clockwise. The antenna should be adjust- ed with minimum power.

.Transmitting with full power is recommended only after the antenna has been adjusted for a

VSWR below 1.5:1.

3.Antenna installation is critical for successful mo- bile operation. For further information refer to THE RADIO AMATEUR'S HANDBOOK, RADIO HAND- BOOK, or other texts.

(2)Coaxial cable connection

When the antenna is mounted on the behicles bum- per, the coaxial cable from the antenna can be routed through a drain hole in the trunk. When the antenna is roof mounted pass the cable between the body and door. Leave a driploop at the lowest point in the cable before entry into the vechicle to prevent water from entering the car.

(3)Adjustment

Some mobile antennas are not designed at 50-ohm im- predance. In this case, impedance matching between the antenna and the coaxial cable (500) is required. This can be achieved by using an antenna matching device or coupler.