
                                                                   Antenna99
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Antenna99  is designed for easy calculation of  Antenna Element diamentions in the HF and VHF range. This Software is very simple to use with input of Frequency (MHz) for which the Antenna is to be designed and Number of Element for the Antenna. The calculations are based on the data taken from the     ARRL -Antenna  Hand Book .The Frequency and the Number of Elements are entered in the appropriate input boxes and the selection button for the type of Antenna is clicked, the required data appears on the Window. The actual length of the Antenna  is dependent on the location, distance from the ground or any fixed structures, size of the Element matrial  etc. The length of the Elements obtained by calculation is approximate and the actual length is obtained by pruning the Elements to minimum possible SWR.

Dipole Antenna:-
 The length of the Antenna Element is calculated by this Software takining into cosideration for the End Effects. 

Inverted V Antenna:-
 End Effects are taken into consideration while calculating the length of the Elements. This Antenna is suported in the middle by a pole and the angle between the elements should be in the range of  90 degrees to 120 degrees. The  angle less than 90 degrees affects the performance of the adversly. This Antenna has got a low angle radiation when compared to Dipole Antenna.

J - Pole Antenna:-
 This Antenna aquires the name because of its physical shape . The performance of this Antenna is almost similar to the SLIM JIM Antenna. It recommended for  use in the VHF range and mounted vertically for vertical polarization. The longest element is the radiating element which is 1/2 wave length and the bottom portion is 1/4 wave length U portion is used as stub matching unit. The hot end of the feeder is connected to the long portion and the other end of the feeder is connected to the short portion. The connections are slided on the stub to obtain minimum possible SWR. This Antenna has got a low angle radiation similar to a vertical antenna and the gain is 3dB compared with a Dipole.

Yagi Antenna:-
  This is a unidirectional  Antenna which has gain ranging from 4dB to 10dB depending on the number of Elements , as given in this Software. The feeder is connected to the driven element using a gamma matching unit.The feeder portion Gamma Matching unit is shown in RED color.

Quad Antenna:-
 This is also a unidirectional Antenna which has an added gain of about 2dB more than the Yagi Antenna for the same number of Elements. Calculation for upto three elements are given in this software. The feed point is in the centre of the bottom length of the driven element loop. The feed impedence is about 50 ohms.The feed point is shown in Red color.

Operating System:-
  Antenna99 works on Win95 or Win98 OS.

Operating Procedure:-
  The frequency and the number of Elements are entered in the appropriate text boxes by highlighting with mouse pointer and the required antenna is to selected from the selection buttons. This program works from 1MHz to 300 MHz.

S.Sundar Atman.
atman@vsnl.com
sundaratman@yahoo.com