MEASUREMENT SCIENCE REVIEW, Volume 7, Section 3, No. 3, 2007 42 Measurement of Semi-Anechoic Chamber Using Modified VSWR method above 1GHz M. Bittera, K. Kováč, J. Hallon Department of Measurement, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovičova 3, Bratislava, 812 19, Slovakia Email: [email protected]Abstract. Most of alternative test places as semi-anechoic chambers are designed to use them for EMI measurement in frequency range 30 ÷ 1000 MHz. Nowadays it is necessary to measure radiated emission also at higher frequencies in some cases. However, no valid standard exists to determine the process of their verification. In this paper modified site VSWR method was used to obtain behaviour and possible utilization of semi-anechoic chamber of EMC Laboratory for measurement at higher frequencies up to 10 GHz in measuring distance 1 m. Keywords: semi-anechoic chambers, site VSWR, verification of test place 1. Introduction The basic standard referring verification of test places for electromagnetic interference (EMI) measurement is [1]. This standard deals with verification only in frequency range 30 MHz ÷ 1 GHz. According to [1] measured values of normalised site attenuation of the test place are compared with ideal ones. The only official document assuming a testing above 1 GHz is a technical specification [2] of ETSI, which assumes also NSA measurement but only anechoic chambers. However, at frequencies above 1 GHz directional broadband antennas shall be used, so effect of absorbers manifests itself in results at minimally 10 m measuring distance [3]. An alternative method replacing NSA measurement is described in [4]. The method is based on measurement of voltage standing-wave ratio (VSWR) that indicates differences in field distribution inside test place. This method is convenient also for anechoic chambers, but there are no measuring distance conditions. Therefore this method was used to survey properties of semi-anechoic chamber of EMC Laboratory of our university in frequency range 1 ÷ 10 GHz using some modifications. 2. Subject and Methods Site VSWR method is based on moving transmitting source along measurement axis to sample standing wave of electromagnetic field. The VSWR value is given as ratio of maximum and minimum signal for measurement series: min max min max V V E E VSWR = = (1) where E max and E min are maximal and minimal value of measured E-field and similarly for values of measured voltages on receiving antenna terminals V max and V min . The value of VSWR determines field uniformity instead of space attenuation, while it does not depend on antenna factor and cable loss accuracies.
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CLASS REGISTRATION BEGINS NOVEMBER 21, 2015 AT 10:00AM
See page 2 of this brochure for more details.
WINTER 2016 WINTER 2016
CLASS SCHEDULECLASS SCHEDULE
Scripps Ranch Recreation Center 11454 Blue Cypress Drive, San Diego, CA 92131
“We enrich lives through quality parks and programs”
HOURS OF OPERATION
Monday - Thursday
11:00 AM - 9:00 PM
Friday
10:00 AM - 7:00 PM
Saturday
9:00 AM - 4:00 PM
Sunday
12:00 PM - 4:00 PM
REGISTRATION HOURS
Monday - Thursday
12:00 PM - 7:00 PM NO REGISTRATION OR PERMITS
FRIDAYS - SUNDAYS
*Park Use Permits and
Recreation Center Use
Permits are processed
by appointment only.
Please contact the Scripps Ranch Staff at
(858) 538-8085 for availability.
2
Cathy Lawler
Area Manager II
Claudia Apodaca
Center Director III
Michael Stark
Assistant Center Director
Tony Cruz
Ground Maintenance Worker II
Maile Cabanas
Recreation Leader I
Debra Davison
Recreation Leader I
Porsha Standard
Recreation Leader I
Debra Smith
Recreation Leader I
Online Registration will be available this season.
Children under 18 must be registered by their parent/legal guardian.
NO EXCEPTIONS!
AS A RECIPIENT OF FEDERAL FUNDS, THE CITY OF SAN DIEGO CANNOT DISCRIMINATE AGAINST ANYONE ON THE BASIS OF COLOR, GENDER, RELIGIOUS CREED, MARITAL STATUS, SEXUAL ORIENTATION, ANCESTRY, NATIONAL ORIGIN,
AGE, MENTAL OR PHYSICAL DISABILITY, OR MEDICAL CONDITION (INCLUDING HIV, AIDS AND AIDS RELATED COMPLEX). IF ANYONE BELIEVES HE OR SHE HAS BEEN DISCRIMINATED AGAINST, HE OR SHE MAY FILE A COMPLAINT ALLEG-
ING THE DISCRIMINATION WITH EITHER THE CITY OF SAN DIEGO PARK AND RECREATION DEPARTMENT (CONTACT DISTRICT MANAGER AT 619-235-1133) OR THE OFFICE OF EQUAL OPPORTUNITY, U.S. DEPARTMENT OF INTERIOR, WASH-
INGTON D.C. 20240. THIS INFORMATION IS AVAILABLE IN ALTERNATIVE FORMATS UPON REQUEST.
REGISTRATION BEGINS:
SATURDAY, November 21, 2015 at 10:00AM
Registration at the Recreation Center will be done on a first come,
first serve basis.
REGISTRATION INFORMATION
Historically, only a few classes fill to capacity on the first day of
registration; register early for best availability. When classes fill to capacity,
waiting lists are formed. Many classes are expanded to accommodate addi-
tional students. However, to insure program quality for all participants, no
exceptions are made regarding class enrollment sizes. Programs may be can-
celled if the minimum enrollment requirement is not met 48 hours prior to the
start of the first class. Please register early. All participants must meet age
requirements.
◆ Payment is required at the time of registration.
◆ Payment methods for registrations taken at the Center are a credit
card, EXACT cash or a check payable to SRRC.
◆ Online Class registration requires a credit card payment.
◆ Credit cards accepted are VISA, MasterCard, American
Express and Discover. We are unable to accept debit cards.
◆ A $35 fee will be charged for all returned checks.
◆ Financial assistance is available. Please submit the application to
Recreation Center office one week prior to the start of
registration.
◆ Class fees are not prorated/discounted after the beginning of the
scheduled session.
This policy applies to programs offered by the Scripps Ranch
Recreation Council. Sorry, no refunds available for programs
with less than 4 class meetings. No partial refunds or make ups for
missed classes (i.e. routine illness, vacation or other schedule con-
flict). Sorry, no exceptions!
A $15 service fee will be charged per registrant for each refund
request. Refunds are processed within 10 business days of request.
All approved refund requests will be paid via check. This includes
credit card transactions. A CVRC Refund Request Form
(available at the Recreation Center) and your registration receipt
must be submitted at least 48 business hours prior to the second
scheduled class meeting.
Due to the nature of their business, class instructors rely on regis-
tration numbers in order to plan safe and well supervised classes.
If you or your child are unhappy, or your child does not partici-
pate after the refund deadline, we cannot process a refund or trans-
fer. Thank you for understanding.
PAYMENT POLICY:
REFUND POLICY:
Effective September 8, 2015 processing fees will apply as
follows for all transactions. For Online Registration, $2
transaction fee and 3% processing fee will be charged for
every transaction. For In-house registration, $2 transaction
fee will be charged for every transaction. Rates are
established by the service provider and are non refundable.