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Minimum Antenna Separation

Apr 29th 2021, 11:49


Joined: Apr 19th 2006, 10:18
Total Topics: 0
Total Posts: 0
I recently installed a Broad Band Terminated Dipole (BBTD) antenna on my roof. It works great. However, the antenna is very close to my 2M / 440 antenna. Both antennas are connect to my IC7000 radio. Another amateur suggested that the antennas might be too close to one another and could damage the front end of my radio. The antennas are cross polarized with the 2M / 440 being vertically polarized and the BBTD being horizontally polarized. Is this an issue? I don't want to damage my radio. I've been disconnecting each antenna until I can figure out if this is a problem or not. Thanks!

May 15th 2021, 17:41

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Most important is for you to establish a single point ground for the feeds for both antennas, and for your station AC power, phone lines, wired Ethernet, etc. Installing current baluns (ferrite beads) on the coax for each antenna will also help minimize currents induced from one antenna onto the feed coax of the other. If the U/VHF antenna has a DC ground design, this will essentially short out any pickup from the HF antenna. In my experience with a similar arrangement, this was not a problem. You would need an RF voltmeter to measure how much HF energy is getting into the U/VHF antenna feed to see if there is a real problem. One way to fake an RF voltmeter is to use an RF power meter and a dummy load. Put a HF wattmeter on your U/VHF coax and on a dummy load, then you can measure the power picked up by the U/VHF antenna when you transmit on HF. If it is less than 1 Watt, it should not be a problem. Hope this helps! 73, Avery WB4RTP

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