FEATURE TEST & MEASUREMENT
Interference hunting made easy – with handheld directional antenna
Maik Reckeweg, product manager at Rohde & Schwarze explores how the latest handheld directional antenna offers portability and functionality in a compact light weight form factor
M
any different user groups appreciate portable radiomonitoring equipment
that can also be used to (manually) take bearings. Users range from mobile network operators and regulatory authorities to facility security companies, armed forces and intelligence services. Depending on the actual application, either the receiver or one of the spectrum analysers is used – the new R&S HE400 antenna is compatible with all of them.
LIGHTWEIGHT, COMPACT AND INTUITIVE TO USE The antenna comes with a handle, a receiver-specific cable set and one of five currently available plug-in modules that together cover the frequency range from 8.3kHz to 8GHz (Fig. 1). The handle and antenna modules are made of PC/ABS plastic or aluminim for low weight (approx. 1kg) combined with high impact resistance. The antenna is supplied from the receiver or spectrum analyser, which further reduces the weight since batteries are not required in the antenna. The ergonomic handle rests comfortably
in your hand and the two controls (trigger button and toggle button) are easy to reach with thumb and index finger. For prolonged work periods, the armrest included with the antenna should be used; it simply attaches to the handle (Fig. 2). The toggle button activates the low-noise amplifier (LNA) integrated into the handle. The handle also includes an electronic compass and a dual GPS/GLONASS receiver. Positions and bearings obtained in this manner are transmitted to the connected receiver, which also automatically recognises the type of antenna module that is plugged and the status of the LNA. Field strength values are therefore always displayed correctly – without requiring any user settings (Fig. 3). To start a measurement or action that
was predefined in the receiver, the user simply presses the trigger button on the handle. The position of the transmitter can be calculated using triangulation and displayed on a map.
16 DECEMBER/JANUARY 2019 | ELECTRONICS Figure 1:
Five plug-in modules are currently available. Shown here is the VHF module with the PR100 portable receiver
Figure 2:
The attachable armrest allows fatigue-free operation over long periods of time
This module uses a special, more precise direction finding method than, for example, log-periodic or loop antennas. At the press of a button on the handle, the broadband dipoles that are next to each other can be switched between normal mode and delta mode. In normal mode, the dipoles work in-phase, producing a relatively broad radiation pattern to the front. In delta mode, the two dipoles are excited out-of-phase, producing a radiation pattern with a steep notch in the line-of-sight direction. In practice, normal mode is used to determine the general direction. The user then switches to delta mode and moves the antenna only in the angular range of the previously determined maximum. Thanks to the very narrow notch in the radiation pattern, minimum-signal direction finding can be used to precisely determine the direction.
MODULES AND CABLES In addition to the familiar loop modules for HF and VHF that were also available for the company’s HE300 and a broadband log-periodic module for UHF and SHF, there are two new modules. The ultrawideband module covers the extremely wide frequency range from 30MHz to 6GHz. In many applications, this module greatly simplifies antenna handling since it eliminates the need to exchange modules. The R&S HE400UWB combines two separate antennas in a single radome. The antennas are interconnected via a diplexer. The company’s HE400CEL
cellular module is designed specifically for the cellular bands from 700MHz to 2.5GHz.
Figure: 3:
R&S PR100 display showing the field strength, compass and GPS data
CONFIGURATION AND ACCESSORIES The R&S HE400 can be configured to meet customer-specific requirements. The antenna modules are simple to plug in and secure with a locking nut. Receiver-specific cable sets are available to connect to one of the three currently supported receiver devices. These cable sets can be quickly assembled by the user and are also easy to exchange during servicing. Available accessories include a rugged
transport case with room for the antenna handle, all antenna modules and the R&S PR100 monitoring receiver. Two compact transport bags for transporting two or four modules are also available. The handle has a threaded socket that is used to mount the antenna on a tripod such as the lightweight R&S HE400Z4 with spherical head.
Rohde & Schwarz
www.rohde-schwarz.com T: 01252 818 888 e:
Contact.uk@rohde-
/ ELECTRONICS
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