The antenna design proposed below Gajarski, HA4YD. It has a gain of 18 dB in the range 144-144. 5 MHz, 17,75 dB at a frequency of 145 MHz and 17.4 dB at 146 MHz. As can be seen from figure - this antenna is a hybrid of the wave channel and antenna automatic process.
Fig.1
Antenna impedance is 110 Ohms. To align with the 50-Ohm coaxial cable is short-circuited loop, the design of which is shown in Fig.2. You should pay attention to the U-shaped jumper is part of the automatic process of the antenna, whose length is 178 mm.
Fig.2
The antenna elements are made of aluminum tubes with a diameter of 6 mm. Bearing cross member made of a tube with a diameter of 30 mm. Holders split vibrators are made of insulating material (Teflon, PTFE, fibreglass, plexiglass, etc.) and for solid vibrators - aluminum (Fig.3).
Fig.3. Design of holders for slotted (top) and solid (bottom) elements
Literature:
Author: W. FAULHABER - Y28RL/Y38ZL, Translated from German by N. Bolshakova, RA3TOX; Publication: N. Bolshakov, rf.atnn.ru