TEKBOX TBMA5 Active Monopole Antenna Owner’s Manual

V1.0
TBMA5
Active Monopole Antenna

Introduction

The TBMA5 is an active Monopole Antenna, expanding the Tekbox product range of affordable EMC pre-compliance test equipment. The monopole antenna is designed for radiated emission measurements within the frequency range 9 kHz ­ 30 MHz, according to CISPR 16. The monopole antenna has a rod with height of 104 cm and provides sufficient sensitivity to carry out radiated emission measurements as specified in CISPR 25 or MIL-STD-461G.

The TBMA5 consists of an impedance converter, a universal charger, a 10 mm diameter rod, a 60 cm x 60 cm ground plane and a standard 10pF calibration adapter. Furthermore, it includes the coaxial cable with ferrite and grounding equipment required under MIL-STD461G. The impedance converter is equipped with a ¼” thread to attach it to conventional tripods.

Specification

Antenna factor

The antenna factor AF is an antenna and frequency dependent parameter, which is required to convert the voltage measured at the output of an antenna into the corresponding electric field strength. For electric field strength:

E[dBµV/m] = V[dBµV] + AFE[dB/m] Where AFE is the electric antenna factor in [dB/m]

Antenna factor table

Frequency [MHz| Electric field antenna factor
[dB/m]| Magnetic field antenna factor
[dB/Ωm]| Uncertainty [dB]
---|---|---|---
0,009| 6.71| -44.79| ±1.00
0,010| 6.64| -44.86| ±1.00
0,020| 6.39| -45.11| ±1.00
0,030| 6.34| -45.16| ±1.00
0,040| 6.32| -45.18| ±1.00
0,050| 6.3| -45.2| ±1.00
0,060| 6.29| -45.21| ±1.00
0,070| 6.29| -45.21| ±1.00
0,080| 6.28| -45.22| ±1.00
0,090| 6.28| -45.22| ±1.00
0,100| 6.28| -45.22| ±1.00
0,110| 6.27| -45.23| ±1.00
0,120| 6.27| -45.23| ±1.00
0,130| 6.27| -45.23| ±1.00
0,140| 6.26| -45.24| ±1.00
0,150| 6.26| -45.24| ±1.00
0,200| 6.26| -45.24| ±1.00
0,300| 6.26| -45.24| ±1.00
0,400| 6.26| -45.24| ±1.00
0,500| 6.26| -45.24| ±1.00
0,600| 6.25| -45.25| ±1.00
0,700| 6.24| -45.26| ±1.00
0,800| 6.24| -45.26| ±1.00
0,900| 6.23| -45.27| ±1.00
1,000| 6.23| -45.27| ±1.00
2,000| 6.22| -45.28| ±1.00
3,000| 6.22| -45.28| ±1.00
4,000| 6.21| -45.29| ±1.00
5,000| 6.21| -45.29| ±1.00
6,000| 6.19| -45.31| ±1.00
7,000| 6.19| -45.31| ±1.00
8,000| 6.18| -45.32| ±1.00
9,000| 6.18| -45.32| ±1.00
10,000| 6.18| -45.32| ±1.00
11,000| 6.18| -45.32| ±1.00
12,000| 6.19| -45.31| ±1.00
13,000| 6.2| -45.3| ±1.00
14,000| 6.21| -45.29| ±1.00
15,000| 6.23| -45.27| ±1.00
16,000| 6.24| -45.26| ±1.00
17,000| 6.26| -45.24| ±1.00
18,000| 6.29| -45.21| ±1.00
19,000| 6.31| -45.19| ±1.00
20,000| 6.33| -45.17| ±1.00
21,000| 6.36| -45.14| ±1.00
22,000| 6.39| -45.11| ±1.00
23,000| 6.41| -45.09| ±1.00
24,000| 6.45| -45.05| ±1.00
25,000| 6.48| -45.02| ±1.00
26,000| 6.51| -44.99| ±1.00
27,000| 6.55| -44.95| ±1.00
28,000| 6.58| -44.92| ±1.00
29,000| 6.62| -44.88| ±1.00
30,000| 6.66| -44.84| ±1.00

Table 1: TBMA5 antenna factors, 9 kHz ­ 30 MHz, typical values

VSWR

Calibration

The TBMA5 already comes with a factory calibration protocol. The calibration accessory enables periodic re-calibration or validation of the performance, if required. The calibration process for obtaining the antenna factor is based on the Equivalent Capacitance Substitution Method (ECSM). It is a two-step procedure:
– Normalizing procedure
As shown in the picture below, both 50 RF ports of a vector network analyzer/spectrum analyzer are connected to both sides of a coaxial T adapter, combined with two 10 dB N-type

Active Monopole Antenna
attenuators in order to improve matching of the VNA ports. The 10 pF calibration capacitor, which is attached to the input port of the impedance converter to simulate the high impedance of the 104cm rod element of the TBMA5 antenna. A 50 termination is connected to the output port of the antenna for the normalization purpose. Next, a S21 Through Calibration is carried out within the frequency range of the antenna.

– Measurement procedure
For the measurement procedure as shown in the picture below, the RF input port of the vector network analyzer/spectrum analyzer (port 2) is now detached from the coaxial T adapter and is connected to the output port of the TBMA5 antenna while it is still attached to the 10 dB Ntype attenuator. The 50 termination load is now connected to the coaxial T adapter. Next carry out a S21 measurement, which represents the gain of the impedance converter.

Using the described method, the antenna amplifier gain and the active antenna factor can be calculated using the following equations respectively:
Amplifier Gain = S21 (Impedance Converter) [dB] Antenna Factor = 6.02 – Amplifier Gain [dB/m]

Sensitivity

The sensitivity of a radiated noise measurement setup looks at the base noise of the available spectrum analyzer or measurement receiver. Applying the antenna factor gives the resulting minimum detectable electric field for the active monopole antenna. this noise floor has to be at least 6 dB below the emission limits of the applied standard.
To measure the sensitivity of the antenna @ 1MHz and 1KHz RBW, the minimum signal should be at least 6 dB above the noise floor of the available spectrum analyzer /measurement receiver in order to be clearly distinguishable from the noise level according to CISPR 16 standard.

Accessories

The TBMA5 comes in an aluminum carrying case and includes the impedance converter, a universal charger, a ground panel, a rod, a calibration adapter and a MIL-STD-461G ground bonding kit consisting of a 125cm long coaxial cable with ferrite sleeve and a ground bonding adapter.

Inserting / replacing batteries

Due to airfreight regulations the TBMA5 does not include rechargeable batteries. Before operation, it is necessary to insert 6 pieces standard 1.2V NiMH batteries.
Remove the four screws at the bottom base plate of the impedance converter housing, lift it, and insert six AA rechargeable 1.2V NiMH batteries. Both the battery compartment and the PCB indicate the polarity. Re-attach the bottom base plate, then tighten the screws.

Ordering Information

rod, 60 cm x 60 cm ground panel, 10 pF calibration adapter, coaxial T-adapter, 2 pcs 10 dB attenuators, Mil-STD-461 ground bonding kit consisting of a 125 cm long 50 Ohm coaxial cable, a ferrite sleeve and a ground bonding adapter
Aluminum carrying case
NIST traceable factory calibration certificate & report

History

www.tekbox.com
TekBox Digital Solutions Vietnam Pte. Ltd.
Factory 4, F4, Lot I-3B-1, Saigon Hi-Tech Park, Tan Phu Ward, District 9, Ho Chi Minh City, Vietnam

References

• Tekbox Digital Solutions |

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