Sunday, April 7, 2019

Passive repeaters boost signals into valleys

Live in a valley but have access to a hilltop to install an antenna?

If so a passive repeater might be a good project.

Especially if there's a repeater you'd like to work through but can't due to your location.

The Spring 2019 Sprat from the G-QRP Club carried an article by G8SEQ on one.

It draws from a talk by G7III given to the Coventry Amateur Radio Society.

Basically a passive repeater is two antennas mounted on a high spot visible to both the repeater and the station in the valley desiring extended range.

One antenna is beamed towards the repeater while the other is beamed towards you. The antennas are connected with coax cable.

On VHF/UHF they can be yagis while dishes can be used on microwaves. Another approach is to use a larger metal reflector, looking like a drive-in screen.

The increase in signal experienced depends on the reduction in path loss due to the use of the high intermediate location plus the gains of the antennas used.

Passive repeaters have had some use in non-amateur applications. For example improving TV or FM radio reception for people living in valleys. More recently they have been used to extend wi-fi data networks or improve indoor coverage.

Below are some articles on passive repeaters:

* Passive Repeater Engineering by Microflect
* Passive repeater antennas by KR6A
* QRZ thread on passive repeaters
* Discussion on passive TV repeaters

Have you build or used a passive repeater? If so please let me know your experiences in the comments below.

PS: I have written five books on various facets of amateur radio. They are available in electronic or paperback form. Find out more here

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