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Dipolo de 1.2 lambda with gamma match for 88-108 mhz
This is a 1/2 lambda type antenna, typical with gamma match adapter, can be stacked to achieve greater gain, I am preparing the documentation for anyone who may be interested in building
post 27 Apr 2024
Antenna for UHF VHF Links →
Stacking with Coax Cables as Transformation Lines
The stacking cables are made of odd multiples of 1/4-coax-cables 3/4-, 5/4- or 7/4
The HB9CV 144 Antennas
The HB9CV is a well known two element antenna of a directional beam type with a forward gain of 4 to 5 dBd
The normal-mode helix antenna
A helix will work in the normal mode when the diameter and pitch of the helix is less than 0.1 Lambda When working in this mode the radiation is from the side of the helix, and when the diameter is considerably less than 0.1? the resultant 'spring' has a radiation pattern similar to a short vertical monopole or whip
Three Element Collinear J Pole
Working from the short end of the 5 sections of the J and looping counter clockwise through the top PVC Section, here are the measurements I used
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The stacking cables are made of odd multiples of 1/4-coax-cables 3/4-, 5/4- or 7/4
The HB9CV is a well known two element antenna of a directional beam type with a forward gain of 4 to 5 dBd
A helix will work in the normal mode when the diameter and pitch of the helix is less than 0.1 Lambda When working in this mode the radiation is from the side of the helix, and when the diameter is considerably less than 0.1? the resultant 'spring' has a radiation pattern similar to a short vertical monopole or whip
Working from the short end of the 5 sections of the J and looping counter clockwise through the top PVC Section, here are the measurements I used
23cm Yagi Antenna building Finished antenna at 1275 MHz SWR under 1:1.5 at resonant frequency
50 MHz preamp Gain 26dB with the BFG135 Preamps for 144 and 430 MHz, for 50 MHz, the BFG135a is a cheap transistor and in my view rather strong. It is not easily damaged by static discharge or RF power. FG connection
30 Volt Computer Power Supply Stack A bonus was that i discovered that these did not need a standby load connected to the supply to keep them running just apply mains power and close the Start lead to ground